Dissertations / Theses on the topic 'Drug receptors'
To see the other types of publications on this topic, follow the link: Drug receptors.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Drug receptors.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Wright, Sherie Rose. "The role of A2A receptors in drug addiction: interaction with mGIu5 receptors." Thesis, University of Surrey, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.583347.
Full textAbstract:
The mechanism by which the adenosine A2A receptor mediates the actions of multiple drugs of abuse is thought to be partly attributable to interactions with dopamine D2 receptors in the striatum; a key structure in drug-related reward, reinforcement and motor responses. Evidence now suggests that this interaction could be further influenced by actions of the metabotropic glutamate receptor, mGlu5, which is co- expressed with striatal A2A and D2 receptors. This work aimed to identify the role of A2A receptors in mediating the locomotor and stereotypic responses to chronic administration of cocaine, morphine and methamphetamine with the use of wild-type (WT) and adenosine A2A receptor knockout (KO) mice. Further, via quantitative autoradiography in WT and A2A KO mice, the experiments described in this thesis also investigated whether the A2A receptor was involved in the regulation of D2 and mGlu5, receptor binding, both under physiological conditions and following chronic cocaine, morphine and methamphetamine administration. A significant reduction of mGlu5, but not D2 receptor density was observed in the ventral striatum of treatment-naive A2A KO mice, giving further evidence for the presence of a striatal A2A-mGlu5 interaction at the receptor level. Chronic administration of methamphetamine, but not cocaine or morphine, caused a significant upregulation of striatal mGlu5, receptors in WT mice. This was accompanied by the manifestation of a stereotypic rearing behaviour in methamphetamine-treated WT mice, both of which were completely abolished in A2A KO mice, suggesting a drug-specific role of an A2A- mGlu5 receptor interaction in the methamphetamine-induced rearing response. Furthermore, the combination of sub-threshold doses of A2A and mGlu5, receptor antagonists significantly attenuated methamphetamine-induced rearing in WT mice, confirming that a striatal A2A-niGlus interaction was specifically involved in the mediation of this response. Chronic morphine treatment caused an upregulation of thalamic mGlu5 receptors in A2A KO mice, indicating that an A2A-mGlus interaction may also be of relevance in the mediation of morphine-induced antinociceptive tolerance. No changes in D2 receptor binding were observed in either treatment-naive WT or A2A KO mice, or those mice treated chronically with cocaine, morphine or methamphetamine, suggesting that the A2A receptor is not involved in modulating the receptor density of D2 receptors either physiologically, or following chronic drug administration. Collectively, the results described in this thesis show that the contribution of the A2A receptor in mediating the locomotor and stereotypic responses to chronic drug administration is drug-dependent, as is the ability of A2A to regulate mGlu5 receptor binding. Specifically, the therapeutic relevance of the novel A2A-mGlus interaction identified following chronic methamphetamine administration merits further investigation, as it adds to a growing body of evidence which suggest simultaneous targeting of A2A and mGlu5 receptors has implications for the improved efficacy of treatments of basal ganglia disorders and drug addiction.
2
Morizzo, Erika. "G Protein-Coupled Receptors as Potential Drug Target: From Receptor Topology to Rational Drug Design, an in-silico Approach." Doctoral thesis, Università degli studi di Padova, 2009. http://hdl.handle.net/11577/3426081.
Full textAbstract:
G protein-coupled receptors (GPCRs) constitute a very large family of heptahelical, integral membrane proteins that mediate a wide variety of physiological processes, ranging from the transmission of the light and odorant signals to the mediation of neurotransmission and hormonal actions. GPCRs are dysfunctional or deregulated in several human diseases and are estimated to be the target of more than 40% of drugs used in clinical medicine today.
The crystal structures of rhodopsin and the recent published crystal structures of beta-adrenergic receptors and human A2A Adrenergic Receptor provide the information of the three-dimensional structure of GPCRs, which supports homology modeling studies and structure-based drug-design approaches. Rhodopsin-based homology modeling has represented for many years a widely used approach to built GPCR three-dimensional models. Structural models can be used to describe the interatomic interactions between ligand and receptor and how the binding information is transmitted through the receptor.
Both agonist and antagonist like states can be described by several different conformational receptor states depending on the nature of both ligand and receptor. Considering different complementarities, we might explore different conformations of the same pharmacological state.
We investigated the molecular pharmacology of adenosine receptors and, in particular, the human A3 adenosine receptor (hA3AR) by using an interdisciplinary approach to speed up the discovery and structural refinement of new potent and selective hA3AR antagonists. Human A3AR belongs to adenosine receptors family of GPCRs, which consists of four distinct subtypes: A1, A2A, A2B, A3 that are ubiquitously expressed in the human body.
The hA3AR, which is the most recently identified adenosine receptor, is implicated in a variety of important physiological processes. Activation of A3ARs increases the release of inflammatory mediators, such as histamine from rodent mast cells, and it inhibits the production of tumor necrosis factor-alpha. The activation of the hA3AR seems to be involved in immunosuppression and in the response to ischemia of the brain and heart. Agonists or antagonists of A3ARs are potential therapeutic agents for the treatment of ischemic and inflammatory diseases.
The first model of human A3AR has been built using a conventional rhodopsin-based homology modeling approach. The model has been used to probe atomic level specific interactions, detected using site-directed mutagenesis analysis.
The rhodopsin-based model of the hA3AR in its resting state (antagonist-like state) has been revisited, taking into account a novel strategy to simulate the possible receptor reorganization induce by the antagonist-binding. We called this new strategy ligand-based homology modeling (LBHM). It is an evolution of a conventional homology modeling algorithm: any selected atoms will be included in energy tests and in minimization stages of the modeling procedure. Ligand-based option is very useful when one wishes to build a homology model in the presence of a ligand docked to the primary template. Starting from the conventional rhodopsin-based homology model and applying our ligand-based homology modeling implementation we can generate other antagonist-like conformational states of hA3AR in which the ligand recognition cavity is expanded. Using different antagonist-like conformational states, we are able to rationalize the observed activities for all the compounds analyzed. Many severe analysis concerning false-positives and false-negatives situations are usually conducted.
To strictly validate this methodology as novel tool to address the multi-conformational space of GPCRs, we have analyzed different classes of known human A3 antagonists in the corresponding putative ligand binding site: for example triazoloquinoxalin-1-one derivatives, arylpyrazolo-quinoline derivatives and pyrazolo-triazolo-pyrimidines derivatives. These studies led to the identification of groups for every class of antagonists that, introduced one by one in a suitable position, afford high hA3AR affinity and good selectivity.
Starting from these binding requirements, we decided to perform an in silico molecular simplification approach to identify a suitable fragmentation route of the 4-amino-triazoloquinoxalin-1-one scaffold and explore which of the structural features were essential to guarantee efficient ligand-receptor recognition.
With the availability of new three dimensional templates different from rhodopsin, we built new models of hA3AR. All the models were used for a molecular dynamic simulation in a POPC bilayer to investigate the topological fluctuation of the binding pocket.I recettori accoppiati alle proteine G (GPCR) costituiscono una grande famiglia di proteine integrali di membrana caratterizzate da sette eliche transmenmbrana, che mediano un'ampia gamma di processi fisiologici che vanno dalla trasmissione della luce e dei segnali olfattivi alla mediazione della neurotrasmissione e dell'azione degli ormoni. I GPCR mancano di una corretta regolazione in molte patologie umane ed è stato stimato che costituiscano il target del 40% dei medicinali utilizzati attualmente in clinica. La struttura cristallografica della rodopsina e le strutture più recenti del recettore beta adrenergico e del recettore adenosinico A2A forniscono l'informazione strutturale che sta alla base della costruzione di modelli per omologia e degli approcci di structure-based drug design dei GPCR. La costruzione di modelli di GPCR per omologia basati sulla struttura della rodopsina ha rappresentato per molti anni un approccio ampiamente utilizzato. Questi modelli possono essere usati per descrivere le interazioni interatomiche tra ligando e recettore e come le informazioni sono trasmesse attraverso il recettore. Diversi stati conformazionali del recettore possono essere in grado di descrivere la conformazione del recettore che lega l'agonista e quella che lega l'antagonista, a seconda della natura di ligando e recettore. Se si considerano diverse complementarietà, si possono esplorare diversi stati conformazionali di uno stesso stato farmacologico. Noi abbiamo studiato la farmacologia molecolare dei recettori adenosinici e, in particolare, del recettore adenosinico A3 umano (hA3AR), utilizzando un approccio interdisciplinare al fine di massimizzare la scoperta e l'ottimizzazione strutturale di nuovi antagonisti potenti e selettivi per il hA3AR. Il hA3AR fa parte della famiglia dei recettori adenosinici che consiste in quattro diversi sottotipi (A1, A2A, A2B, A3) che sono espressi in tutto il corpo umano. Il recettore adenosinico A3 è stato identificato più recentemente ed è implicato in importanti processi fisologici. L'attivazione del hA3AR aumenta il rilascio di mediatori dell'infiammazione, come l'istamina dalle mastcellule, e inibisce la produzione del TNF-alpha. L'attivazione del hA3AR sembra essere coinvolta nell'immunosoppressione e nella risposta ischemica di cuore e cervello. Agonisti o antagonisti del hA3AR sono potenziali agenti terapeutici nel trattamento di patologie ischemiche e infiammatorie. Il primo modello di hA3AR è stato costruito usando un approccio convenzionale di homology modeling basato sulla rodopsina ed è nel suo stato che lega l'antagonista. Dopo essere stato utilizzato per verificare le interazioni a livello molecolare che erano state evidenziate da studi di mutagenesi, il modello è stato rivisto prendendo in considerazione una nuova strategia che simula la possibile riorganizzazione del recettore indotta dal legame con l'antagonista. Abbiamo chiamato questa strategia ligand-based homology modeling. E' un'evoluzione dell'algoritmo convenzionale di homology modeling: ogni atomo selezionato viente preso in considerazione nei test energetici e nelle fasi di minimizzazione della procedura di modeling. L'opzione ligand-based è molto utile quando si vuole costruire un modello per omologia in presenza di un ligando nella sua ipotetica conformazione di legame nel templato iniziale. A partire dal modello ottenuto dalla rodopsina e applicando la tecnica del LBHM, possiamo generare altri stati conformazionali del recettore hA3AR che legano l'antagonista, nei quali la cavità di riconoscimento del ligando è espansa. Usando diversi stati conformazionali che legano l'antagonista, possiamo razionalizzare l'attività misurata sperimentalmente di tutti i composti analizzati. Sono condotte severe analisi relative a falsi positivi e falsi negativi. Per validare la metodologia come nuovo strumento per indirizzare lo spazio multiconformazionale dei GPCR, abbiamo analizzato diverse classi di antagonisti con attività nota sul hA3AR: ad esempio derivati triazolo-chinossalinonici, derivati arilpirazolo-chinolinici e derivati pirazolo-triazolo-pirimidinici. Questi studi hanno portato all'identificazione di gruppi per ogni classe di antagonisti che, se introdotti in una precisa posizione, portano ad un'alta affinità e ad una buona selettività per il hA3AR. A partire dalle caratteristiche risultate importanti per il legame, abbiamo applicato una tecnica di semplificazione molecolare in silico per identificare una possibile via di frammentazione della struttura 4-amino-triazolochinoassalin-1-onica ed esplorare quali sono le caratteristiche strutturali essenziali per garantire un'efficiente riconoscimento ligando-recettore. Con la disponibilità di nuove strutture tridimensionali da utilizzare come templati diversi dalla rodopsina, abbiamo costruito nuovi modelli del recettore hA3AR. Tutti i modelli sono stati usati per una simulazione di dinamica molecolare in un doppio strato fosfolipidico, per analizzare le fluttuazioni topologiche della tasca di legame.
3
Bertilsson, Göran. "Studies on nuclear receptors involved in drug metabolism /." Stockholm, 2001. http://diss.kib.ki.se/2001/91-628-4697-3/.
Full text
4
Metaxas, Athanasios. "The involvement of nicotinic cholinergic receptors in drug abuse." Thesis, University of Surrey, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520556.
Full text
5
Arif, Khalid. "Evaluation of hormonal receptors in breast cancer drug therapy." Thesis, University of Lincoln, 2014. http://eprints.lincoln.ac.uk/14682/.
Full textAbstract:
Breast cancer is the most common type of cancer in women worldwide. Approximately two-thirds of breast cancers are oestrogen receptor positive (ER+), which are activated via oestrogen dependent and independent mechanisms. The pathogenic role of oestrogen in breast cancer is well established, thus, targeting ER becomes an essential target in breast cancer anti-hormonal therapy. Tamoxifen is the most important anti-hormonal therapeutic agent which has been used as the gold standard in the treatment of ER+ breast cancer patients. Tamoxifen acts by competing with oestrogen for binding to the ER and reduces the transcription of oestrogen dependent genes. However, approximately 30-50% of patients either fail to respond or eventually become resistant to tamoxifen via not fully elucidated mechanisms, resulting in a serious clinical challenge in breast cancer management. Also there is increasing evidence that cancers are driven by cancer stem cells which are characterised by their ability for self renewal and resistance to drug therapies. Therefore the aim of this study was to evaluate the role of oestrogen receptors in both de novo and acquired tamoxifen resistant breast cancer. Study the influence of stem cell factors and the embryonic stemness gene in both MDA-MB-231 and MCF7/Tmx breast cancer cell lines with respect to the hypothesis that anti-stem cell factor and silencing of the Nanog may restore sensitivity to tamoxifen and enhance cell apoptosis. Qualitative and quantitative assays showed significant expression of CD44, PgP, MRP1 and embryonic markers (Nanog, Oct3/4 and Sox2) in MDA-MB-231 and MCF7/Tmx cells. Independently, MDA-MB-231, MCF7/Tmx and parental MCF7/WT cells were treated with monoclonal anti-stem cell factor (ACSF) and interfered with Nanog short interference RNA (siRNA), then growth rate, drug accumulation and apoptosis were assessed in response to 4-hydroxtamoxifen (4-OHT). Quantitative analysis of the influx and efflux rate was performed using the Technetium (99mTc) sestamibi assay in response to blocking SCF. iv Results show a significant apoptosis enhancement after treatment with ASCF in both MDA-MB-231 and MCF/Tmx cells (P<0.005) and a significant increase in the influx rate of 99mTc-MIBI in MDA-MB-231 cells. Growth rate and apoptosis markers were assessed prior to and after the silencing of Nanog gene. Results show a significant increase in apoptosis and reduction in the growth rate in both MDA-MB-231 and MCF/Tmx cells (P<0.005). This study demonstrates that multi drug resistance is mainly a phenomenon of acquired tamoxifen resistance, but not de novo resistance. The inhibition of SCF could inhibit cell proliferation and significantly increases cell sensitivity to tamoxifen in MDA-MB-231 and acquired tamoxifen resistant cells MCF7/Tmx. This study identified a high expression of embryonic markers Nanog, Oct3/4 and Sox2 in both MDA-MB-231 and MCF7/Tmx cells and that the silencing of the Nanog gene reduces cell proliferation and increases apoptosis in MDA-MB-231 and MCF7/Tmx cells. In conclusion, the results suggest that the neutralisation of stem cell factor may play an important role in enhancing tamoxifen response in ER- cells and less in acquired tamoxifen resistant breast cancer cells, via enhancing drug accumulation. The positive association of the embryonic markers with negative (ER-) and acquired tamoxifen resistant breast cancer cells could be used as prognostic markers and the knockdown of these transcription markers could enhance the response to tamoxifen and could be used in the management of breast cancer.
6
Besco, Julie Ann. "Genomic structure and alternative splicing of type R2B receptor protein tyrosine phosphatases, and the role of RPTPrho." Columbus, Ohio : Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1041353035.
Full textAbstract:
Thesis (Ph. D.)--Ohio State University, 2003.Title from first page of PDF file. Document formatted into pages; contains xvii, 227 p. Includes abstract and vita. Advisor: Andrej Rotter, Dept. of Pharmacology. Includes bibliographical references (p. 201-227).
7
Nylander, Sven. "Thrombin/ADP-induced platelet activation and drug intervention /." Linköping : Univ, 2005. http://www.bibl.liu.se/liupubl/disp/disp2005/med885s.pdf.
Full text
8
Leach, Katie. "Pharmacological analysis of the CC chemokine receptors, CCR4 and CCR5 signalling properties and receptor-drug interactions." Thesis, University of Reading, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427859.
Full text
9
Greyerz, Salome Barbara von. "Molecular aspects of drug recognition by specific T cell receptors /." [S.l.] : [s.n.], 1999. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
Full text
10
Jiang, Tian. "Drug affinity and binding site signatures in extrasynaptic GABAA receptors." Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/27104.
Full textAbstract:
GABAA receptors are ligand-gated ion channels that play vital roles in the central nervous system due to their widespread distribution and involvement in vital biochemical process. GABAA receptors that express extrasynaptically are suggested as important targets for treating disorders such as epilepsy, sleep disturbances, stress, and mood disorders. Various pharmaceutical campaigns have succeeded in developing pharmacologically and clinically important drugs for the active sites of GABAA receptors. However, as the drugs do not exclusively bind to the targeted subtypes, they are usually associated with severe side effects. Therefore, it is of great importance to explore binding pockets on extrasynaptic GABAA receptors that have the potential to be targets for subtype-selective drugs that exclusively work on extrasynaptic receptors.
GABAA receptors are assembled from five subunits of four different types, with multiple promising subunit compositions. This results in many different subunit interfaces and binding sites in between subunits. In the present study, possible drug binding pockets on GABAA receptors were mapped and compared, both sequentially and structurally. The neurosteroid and general anesthetic pockets on the α4β3δ GABAA receptor were identified to be more likely targets than other pockets for the development of extrasynaptic-selective drugs. The binding sites on the homology models of GABAA receptors in the active conformation were used in the analysis throughout the thesis, as the determined sites are for positive modulators.
A novel targeted molecular dynamic method was co-developed here for simulating the activation pathway of the α4β3δ GABAA receptor following the path of α1 glycine receptors, as no active conformation has been released for GABAA receptors. During protein activation an increase in the druggability of the receptor was observed, as well as movement correlations in the two determined binding sites. To stabilise the structure of α4β3δ GABAA receptor in the open conformation before investigating the binding sites in the simulation, two equilibration methods were revised and compared here. One of the methods was then chosen to equilibrate the receptor in the active state in the molecular dynamics simulation, as it performed better to keep the protein channel ion-permeable and keep the two determined binding sites stable within the simulation. Significantly, a tilting caused by H-bonds between the β3 and δ subunit was observed during the simulations after equilibration by both methods, which could affect the drug binding to δ-containing GABAA receptors.
Finally, promising sites and binding modes for THDOC and DS2 on α4β3δ GABAA receptor were investigated using molecular docking and molecular dynamics simulations. Residues that form stable contacts with ligands were identified, which offer mutation targets for further confirmation of binding sites. The δN318 residue is suggested here as the key residue that contributes to the favorable binding energy of THDOC on δ+β3– interface, which agrees with the experimental result that THDOC shows a dramatically higher modulation effect on δ-containing receptors than those without the δ subunit. This offers the opportunity to develop δ-selective drugs based on the molecular structure of THDOC.
Together these results provide important new information about drug binding sites in GABAA receptors for developing extrasynaptic-selective drugs for treating epilepsy, sleep disturbances, stress, and mood disorders with minimum side effects. The contributions including information about the binding pockets and unique residues that are potential targets for designing extrasynaptic-selective drugs was identified. The promising binding pockets and binding modes for two drug molecules – THDOC and DS2 was also investigated. Furthermore, novel methodologies have been provided in this thesis for investigating drug binding sites in different conformations and for exploring the activation pathway of GABAA receptors. These methodologies could further be used as tools for understanding the selectivity and druggability of binding sites, simulating the conformational transition pathway, and exploring the subtype-selective drugs on other proteins.
11
Mason, Sarah. "Post-mortem neuropharmacological studies of human and rat brain relating to schizophrenia and antipsychotic drug action." Thesis, University of Sheffield, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364237.
Full text
12
Benjamin, Daniel E. (Daniel Ernest). "The effects of sustained gepirone administration on rodent brain 5-HT receptors and behavioral analogues of anxiety." Thesis, University of North Texas, 1991. https://digital.library.unt.edu/ark:/67531/metadc798440/.
Full textAbstract:
Clinical evidence has demonstrated that the anxiolytic effects produced by the selective 5-hydroxytryptamine1A (5-HT1A) receptor agonist, gepirone, increase progressively over one to three weeks of treatment.
13
Pearce, N. J. "Studies on the mechanism of organ selective receptor occupation by the synthetic thyromimetic SK and F L-94901." Thesis, University of London, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383708.
Full text
14
Arslan, Giulia. "Adenosine A₂A and ATP receptors in PC12 cells /." Stockholm, 2000. http://diss.kib.ki.se/2000/91-628-4028-2/.
Full text
15
Hardman, Karen. "Expression and Characterisation of G-Protein Coupled Receptors for Drug Discovery." Thesis, University of Manchester, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.518457.
Full text
16
Vidgren, Jukka. "Crystallographic studies on drug receptors catechol O-methyltransferase and carbonic anhydrase /." Lund : Dept. of Molecular Biophysics, Lund University, 1994. http://catalog.hathitrust.org/api/volumes/oclc/39725795.html.
Full text
17
Villafranca, Steven Wayne. "The effect of early psychostimulant treatment on abuse liability and dopamine receptors." CSUSB ScholarWorks, 2005. https://scholarworks.lib.csusb.edu/etd-project/2824.
Full textAbstract:
Examines whether the reinforcing properties of drugs of abuse were altered in adulthood by methylphenidate, more commonly known as Ritalin. Subjects were 108 rats of Sprague-Dawley descent (Harlan). Methylphenidate, or saline was administered daily to the subjects from the postnatal period (11-20 days old). The rats preference for morphine during early adulthood was measured using conditioned place preference. The number of dopamine D₂ receptors was measured in each rat and the correlation between receptor number and morphine preference was determined. Results indicate that rats pretreated with methylphenidate showed greater preference for morphine than saline pretreated rats and suggests that exposure to methylphenidate during the postnatal period increases the rewarding value of morphine.
18
Fulton, Joel. "Selective interactions of nuclear receptors and cofactors: novel targets for drug discovery." Thesis, University of Nottingham, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.602958.
Full textAbstract:
Nuclear receptors (NRs) are biomedically important transcription factors that regulate gene expression by recruitment of coactivators and corepressors (cofactors) to target gene promoters. Humans express 48 different NRs.and their isoforms, approximately half of which are orphans that have no recognised ligand. NRs can interact with more than 350 known cofactor proteins, many of which are chromatin modifying enzymes. Binding of ligand induces a conformational change in the NR that stimulates or prevents the docking of cofactors. These interactions are mediated by signature motifs (LXXLL in coactivators; or LXXXIXXXI/L in corepressors) that are essential for NR/cofactor function. To allow broader understanding of cofactor selectivity, an NR LBD interaction panel was constructed consisting of seven ligand-binding and eighteen orphan NRs. Interaction studies using LXXLL motifs from the well-characterised cofactor SRCl and the lesser-studied cofactor MEDl identified distinct patterns of interaction within Class I and Class 11 subsets of NRs. Novel motifs within the developmental regulator BCLllA, with consensus Y /FSXXLXXL/Y, were also investigated, revealing selective binding to a group of related orphan NRs consisting of the NR2E/F subfamilies. This sequence was also found to be conserved in other NR cofactors such as NSDl and was again shown to facilitate interactions with this subset of orphan NRs. As highly social transcription factors, nuclear receptors form a complex and integrated dimerisation network, binding to DNA as monomers, homodimers and heterodimers. While heterodin:terisation of nuclear receptors remains poorly understood, it is known to increase the complexity of NR-mediated transcription by integrating gene networks, mUltiple ligand inputs, cofactor selectivity, and increasing competition for other heterodimeric partners. Having determined the cofactor binding preference of the NR2E/F subfamily we profiled their dimerisation, revealing diverse dimerisation properties and several interactions of interest, including novel complexes of PNR that are likely to be of physiological consequence in the retina. ii
19
Cotter, Rachel. "Trace amine associated receptors : a new target for medications in drug addiction." Thesis, University of Canterbury. Psychology, 2012. http://hdl.handle.net/10092/10803.
Full textAbstract:
The abuse of stimulant drugs, such as methamphetamine (METH), has become a major source of public concern in New Zealand. Specific medications for treating METH addiction are not available at present. The newly discovered trace amine- associated receptor 1 (TAAR1) constitutes a novel receptor target for medication development in neuropsychiatry. TAAR1 regulates monoamine systems in the brain, especially dopamine, and is activated directly by psychomotor stimulants, including METH. This study examined the effects of the newly developed TAAR1 partial agonist, RO5203648, in rat models of METH abuse. In experiment 1 rats were administered different doses of RO5203648 (0, 1.67, 5mg/kg i.p.) followed by METH (0, 0.75, 2mg/kg i.p.). Locomotor activity was monitored via automated video tracking system in an open field. The results revealed that RO5203648 dose- dependently reduced acute METH-induced stimulation and prevented long-term sensitization following chronic exposure. Paradoxically, in experiment 2, RO5203648 and METH treatment increased c-Fos protein expression in the nucleus accumbens and dorsal striatum. In experiment 3 rats were trained to consistently self-administer METH (0.5mg/kg/infusion) and were then pre-treated with RO5203648 (0, 3, 10mg/kg i.p.). The data showed that RO5203648 drastically reduced METH intake. Next, RO5203648 was substituted (0.25, 0.5, 1.0 mg/kg/infusion) for METH in the same paradigm. Remarkably, RO5203648 exhibited no reinforcing efficacy compared with METH. Taken together, these observations showed that RO5203648 is able to attenuate METH-related behaviours, including locomotor stimulation, sensitization and self-administration, and highlight the great potential of TAAR1-based medications for the treatment of METH addiction.
20
Johnson, Kenyetta Alicia. "Extending chemical complemenation to bacteria and furthering nuclear receptor based protein engineering and drug discovery." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29652.
Full textAbstract:
Thesis (Ph.D)--Chemistry and Biochemistry, Georgia Institute of Technology, 2009.Committee Chair: Doyle, Donald; Committee Member: Barry, Bridgette; Committee Member: Bommarius, Andreas; Committee Member: Ledoux, Joe; Committee Member: Matsumura, Ichiro; Committee Member: Oyelere, Adegboyega. Part of the SMARTech Electronic Thesis and Dissertation Collection.
21
Henne, Randal Marlow. "Computational studies of G-protein coupled receptors /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/8048.
Full text
22
Owera-Atepo, J. B. "The vagal nerve as a model for drug action on 5-hydroxytryptamine receptors." Thesis, University of Bradford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379818.
Full text
23
Vicente, Carrillo Alejandro. "Sperm Membrane Channels, Receptors and Kinematics : Using boar spermatozoa for drug toxicity screening." Doctoral thesis, Linköpings universitet, Avdelningen för kliniska vetenskaper, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-131862.
Full textAbstract:
Internal fertilization usually implies that a spermatozoon, with intact attributes for zygote formation, passes all hurdles during its transport through the female genitalia and reaches the oocyte. During this journey, millions to billions of other spermatozoa perish. Spermatozoa are highly differentiated motile cells without synthetic capabilities. They generate energy via glycolysis and oxidative phosphorylation to sustain motility and to maintain the stability and functionality of their plasma membrane. In vivo, they spend their short lifespan bathing in female genital tract fluids of different origins, or are in vitro exposed to defined media during diverse sperm handling i.e. extension, cryopreservation, in vitro fertilization, etc. Being excitable cells, spermatozoa respond in vivo to various stimuli during pre-fertilization (capacitation, hyperactivation, oocyte location) and fertilization (acrosome reaction, interaction with the oocyte) events, mediated via diverse membrane ion-conducting channels and ligand-gated receptors. The present Thesis has mapped the presence and reactivity (sperm intactness and kinematics) of selected receptors, water and ion channels in ejaculated boar spermatozoa. The final aim was to find a relevant alternative cell type for in vitro bioassays that could ease the early scrutiny of candidate drugs as well as decreasing our needs for experimental animals according to the 3R principles. Spermatozoa are often extended, cooled and thawed to warrant their availability as fertile gametes for breeding or in vitro testing. Such manipulations stress the cells via osmotic variations and hence spermatozoa need to maintain membrane intactness by controlling the exchange of water and the common cryoprotectant glycerol, via aquaporins (AQPs). Both AQPs-7 and -9 were studied for membrane domain changes in cauda- and ejaculated spermatozoa (un-processed, extended, chilled or frozen-thawed). While AQP-9 maintained location through source and handling, thawing of ejaculated spermatozoa clearly relocated the labelling of AQP-7, thus appearing as a relevant marker for non-empirical studies of sperm cryopreservation. Alongside water, spermatozoa interact with calcium (Ca2+) via the main Ca2+ sperm channel CatSper. Increments in intracellular Ca2+ initiate motility hyperactivation and the acrosome reaction. The four subunits of the CatSper channel were present in boar spermatozoa, mediating changes in sperm motility under in vitro capacitation-inducing conditions (increased extracellular Ca2+ availability and bicarbonate) or challenge by the CatSper antagonists mibefradil and NNC 55-0396. Uterine and oviduct fluids are richest in endogenous opioids as β-endorphins during mating and ovulation. Both μ- and δ- opioid receptors were present in boar spermatozoa modulating sperm motility, as in vitro challenge with known agonists (μ: morphine; δ: DPDPE and κ: U 50488) and antagonists (μ: naloxone; δ: naltrindole and κ: nor-binaltrorphimine) showed that the μ-opioid receptor maintained or increased motility while the δ-opioid receptor mediated decreased motility over time. Finally, boar spermatozoa depicted dose-response effects on sperm kinematics and mitochondrial potential following in vitro challenge with 130 pharmacological drugs and toxic compounds as well as with eight known mito-toxic compounds. In conclusion, boar spermatozoa expressing functional water (AQPs-7 and -9) and ion (CatSper 1-4) channels as well as μ- and δ-opioid receptors are able to adapt to stressful environmental variations, capacitation and pharmacological compounds and drug components. Ejaculated sperm suspensions are easily and painlessly obtained from breeding boars, and are suitable biosensors for in vitro drug-induced testing, complying with the 3R principles of reduction and replacement of experimental animals, during early toxicology screening.
24
Kanumilli, Srinivasan. "An investigation of glial metabotropic glutamate receptors and their signalling mechanisms." Thesis, University of Bristol, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364911.
Full text
25
Neilan, Claire L. "In vitro and in vivo characterisation of buprenorphine and other long-lasting opioids." Thesis, Loughborough University, 1999. https://dspace.lboro.ac.uk/2134/14129.
Full textAbstract:
Buprenorphine is a promising medication for the treatment of opiate abuse. The pharmacology of buprenorphine has been studied in vitro using radioligand binding and [³⁵S]GTPγS assays, and in vivo using assays of antinociception in rodents. A number of compounds with potential similar pharmacology have also been characterised. These are an iso-morphinan pyrrolidine derivative, and long-lasting 14-aminomorphinones and codeinones, in particular clocinnamox (C-CAM), a pure μ-antagonist and methoclocinnamox (MC-CAM), which has some agonist properties.
26
Thirtamara, Rajamani Keerthi Krishnan. "Animal Models of Drug Addiction and Autism Spectrum Disorders." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1386011455.
Full text
27
Casanovas, Ferrero Mireia. "Complejos del receptor sigma y de heterómeros de receptores acoplados a proteínas G en adicción y control de apetito." Doctoral thesis, Universitat de Barcelona, 2021. http://hdl.handle.net/10803/673826.
Full textAbstract:
Actualmente, entre el 30-40% de los medicamentos comercializados tienen como diana a un receptor acoplado a proteína G (GPCR). Además, la capacidad que tienen estos receptores para interaccionar físicamente entre ellos y formar nuevas unidades funcionales con propiedades farmacológicas distintas a las que tienen sus componentes individuales, permite generar nuevas dianas terapéuticas para combatir distintas enfermedades como la adicción a sustancias de abuso. Aunque millones de personas sufren de adicción en todo el mundo, actualmente no existe ninguna cura. Entre otros efectos adversos, el consumo de psicoestimulantes provoca un estado de euforia debido a una sobreestimulación del sistema de recompensa, inhibición del apetito, sensibilidad a situaciones de estrés y, a largo plazo, neurodegeneración. Se ha demostrado que determinadas sustancias de abuso, como la cocaína o las anfetaminas, son capaces de ejercer parte de sus efectos a través de su interacción con los receptores sigma (V1R y V2R), que, a su vez, son capaces de interaccionar y modular la señalización de otras proteínas, como los GPCR. Así, el principal objetivo de esta Tesis Doctoral ha sido estudiar la posible formación de complejos entre GPCR y receptores sigma implicados en la adicción a psicoestimulantes y en la inhibición del apetito. Durante la realización de esta Tesis Doctoral se han usado técnicas de transferencia de energía y de complementación biomolecular, además del ensayo de ligación por proximidad, para demostrar la formación de oligómeros entre GPCR y receptores sigma. Además, se ha estudiado la huella de estos heterómeros analizando la acumulación de AMPc en el citosol, la liberación de calcio desde el retículo endoplásmico, la activación de la vía de las MAPK, el reclutamiento de E-arrestinas y la redistribución dinámica de masas. Los resultados de esta Tesis Doctoral ponen de manifiesto un papel muy importante de la heteromerización de los GPCR en el mecanismo molecular que regulan los procesos de adicción a psicoestimulantes y la inhibición del apetito. En primer lugar, se han propuesto dos mecanismos moleculares mediante los cuales la cocaína, a través de su unión a V1R, puede mediar su acción anorexigénica. En concreto, la cocaína es capaz de bloquear completamente la señalización inducida por la hormona orexigénica grelina y de alterar la funcionalidad del complejo tetramérico formado por un homodímero de receptores de dopamina D1 y un homodímero de receptores de grelina 1a capaz de señalizar a través de una Gs y una Gq. En segundo lugar, se ha demostrado que el receptor de orexina 1 y el receptor del factor liberador de corticotropina 2 son capaces de heteromerizar y podrían tener un papel muy importante en el estrés y la recaída en el consumo de anfetamina. Finalmente, se ha observado que la metanfetamina, a través de su unión a V1R, altera la funcionalidad del heterómero formado por el receptor de adenosina A2A y el receptor cannabinoide CB1, siendo ambos receptores objeto de estudio en la neuroprotección. Así, el heterómero A2AR-CB1R podría ser una buena diana terapéutica para combatir la neurodegeneración asociada a un consumo crónico de metanfetamina.G protein-coupled receptors (GPCR), which comprise the largest superfamily of plasma membrane proteins in mammals, have had a strong interest in biomedical research. Indeed, between 30-40% of the current drugs marketed target a GPCR. In addition, these receptors are able to physically interact between them creating new functional units with significantly different pharmacological properties than those of their individual components. In this way, heteromerization among GPCR is a novel strategy to look for new therapeutic targets to combat a large variety of diseases, such as drug addiction. Even though millions of individuals suffer from addiction, currently there is no cure available. Among many effects, the use of psychostimulants causes euphoria due to an overstimulation of the reward system, inhibition of appetite, sensitivity to stress, and, in the long term, neurodegeneration. Research in this area revealed that some substances of abuse, including cocaine and amphetamines, are able to exert part of their effects through their interaction with sigma receptors (V1R and V2R). Several authors have published that sigma receptors are able to interact and modulate the signalling of other proteins, such as GPCR. Thus, the main objective of this Thesis has been to study the possible formation of complexes between GPCR and sigma receptors involved in psychostimulant addiction and appetite suppression. During the development of this Thesis, resonance energy transfer and bimolecular complementation techniques, and proximity ligation assays have been used to demonstrate the formation of GPCR and sigma receptors oligomers. Moreover, the fingerprint of these heteromers has been studied by analysing the signalling pathways through measurement of cAMP accumulation in the cytosol, calcium release from the endoplasmic reticulum, MAPK pathway activation, E-arrestin recruitment and dynamic mass redistribution. The results of this Thesis reveal a very important role of GPCR heteromerization in the molecular mechanisms that regulate both drug addiction and appetite suppression. Firstly, it has been proposed two molecular mechanisms by which cocaine, binding to V1R, may mediate its anorexigenic action. Deep inside, cocaine completely blocks the signalling induced by the orexigenic hormone ghrelin and affects functionality of the tetrameric complex consisting of one homodimer of dopamine D1 receptor and one homodimer of ghrelin 1a receptor capable of signalling through a Gs and a Gq. Secondly, it has been observed that the orexin receptor type 1 and the corticotropin-releasing factor receptor type 2 are able to heteromerize and could play a key role in stress and relapse of amphetamine use. Finally, it has been shown that methamphetamine, via interacting with V1R, alters the correct functionality of the heteromer formed by the adenosine A2A receptor and the cannabinoid CB1 receptor, both of them targets for neuroprotection. Therefore, the A2AR-CB1R complexes appear as new therapeutic target to combat neurodegeneration associated with chronic methamphetamine use.
28
Sahm, Ulrike Gisela. "Interaction of naturally occurring and synthetic MSH peptides with peripheral and CNS melanocortin receptors." Thesis, University of Bath, 1994. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385312.
Full text
29
Bills, Kyle. "Mechanoreceptor Activation in the Treatment of Drug-Use Disorders: Mechanism and Outcome." BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/8627.
Full textAbstract:
The therapeutic benefits attributed to activation of peripheral mechanoreceptors are poorly understood. There is growing evidence that mechanical stimulation modulates substrates in the supraspinal central nervous system (CNS) that are outside the canonical somatosensory circuits. This work demonstrates that activation of peripheral mechnoreceptors via mechanical stimulation (MStim) is sufficient to increase dopamine release in the nucleus accumbens (NAc), alter neuron firing rate in the ventral tegmental area (VTA) and increase membrane translocation of delta opioid receptors (DORs) in the NAc. Further, we demonstrate that these effects are dependent on DORs and acetylcholine receptors. Additionally, MStim can block neuronal markers of chronic ethanol dependence including ethanol-induced changes to VTA GABA neuron firing during withdrawal, and DA release profiles after reinstatement ethanol during withdrawal. These are presented in tandem with evidence that MStim also ameliorates behavioral indices of ethanol withdrawal. Finally, exercise, a modality that includes a mechanosensory component, is shown to alter expression of kappa opioid receptors (KORs) in the NAc. This change substantively depresses KORs influence over evoked DA release in direct contraversion to the effects of chronic ethanol. These changes translate into reduced drinking behavior.
30
Acharya, Deepak. "Creating chimeras of human G-protein coupled receptors (HGPR40/43) for diabetic drug development." Muncie, Ind. : Ball State University, 2009. http://cardinalscholar.bsu.edu/398.
Full text
31
Van, Den Bergh Annelies. "The human metapneumovirus and its interactions with the host cell surface receptors." Thesis, Griffith University, 2023. http://hdl.handle.net/10072/421390.
Full textAbstract:
Human viral pathogens are the main causative agents of pneumonia and bronchiolitis in infants and children, posing a large socioeconomic disease burden, associated with a high death toll. Among them, human metapneumovirus (HMPV) has been recently recognised as a leading cause of respiratory disease. The populations most at risk for developing severe HMPV-associated disease are young children, the elderly, and immunocompromised people. Mortality rates in these susceptible groups, especially in immunocompromised individuals, can be as high as 10%. Currently, there is neither vaccine nor drug therapy available to prevent or treat HMPV infection.
Human metapneumoviruses are decorated with three surface glycoproteins: fusion protein (F), attachment protein (G), and small hydrophobic protein (SH). The F protein plays important key roles during various stages of the HMPV lifecycle such as recognition
and binding to host cell receptor, fusion of virus envelope with host cell membrane, and cell to cell membrane fusion. As a result, the F protein is considered as a promising target for antiviral drug discovery. However, little is known about the interaction between HMPV F and its host cell surface receptors, except for heparan sulfate, a glycosaminoglycan which has been proposed to act as the initial receptor.
In this thesis, we first aim to contribute to the discovery of HMPV therapeutics by identifying approved drugs that may be rapidly repurposed as anti-HMPV agents. Next, we aim to fill the knowledge gap related to HMPV F and its host cellular receptors, with a focus on glycoreceptors, as heparan sulfate has been described as the primary host attachment factor. Lastly, we aimed to build a drug discovery toolkit including two highly valuable models that can be used for further rational drug design and early-stage preclinical drug candidate evaluation. In this thesis we present the discovery of novel anti- HMPV inhibitors and provide relevant models for future drug development.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Institute for Glycomics
Science, Environment, Engineering and Technology
Full Text
32
Vearing, Christopher John, and chris vearing@med monash edu au. "Structure, function & control of the EphA3 receptor tyrosine kinase." Swinburne University of Technology, 2005. http://adt.lib.swin.edu.au./public/adt-VSWT20051017.094940.
Full textAbstract:
The implication of the transmembrane signalling Receptor Tyrosine Kinases
(RTKs) in cancer has accelerated the pursuit for drugs to target these
molecules. In the process our understanding of how these membrane bound
molecules are entangled in cell signalling has significantly expanded. There is
now evidence that RTKs can facilitate the formation of a lattice-type network of
signalling molecules to elicit whole cell responses to external ligand stimuli.
Although beginning to be unravelled, knowledge pertaining to the mechanisms
of molecular control that initiate these signalling pathways is still in its infancy.
In this thesis, a random mutagenesis approach allowed the identification of the
crucial interaction surfaces between membrane-bound EphA3 and its
preferential binding partner ephrinA5, that are required to induce the formation
of higher-order Eph signalling complexes. Modelling and experimental
dissection of this co-ordinated receptor aggregation has provided detailed
insights into the molecular mechanisms of Eph receptor activation, which in
some aspects may also apply to other members of the RTK family. In particular,
the importance of certain molecular interfaces in determining preferential and
non-preferential Eph/ephrin interactions, suggests their role in the selection of
biologically important binding partners.
In addition to the assignment of the ephrin-interaction surfaces, the random
mutagenesis strategy also identified a continuous conformational epitope as
binding site for an anti-EphA3 monoclonal antibody. Fortuitously, antibody
binding to this site functionally mimics ephrin stimulation of EphA3 positive cells,
and in particular together with divalent ephrinA5, yields synergistically enhanced
EphA3 activation. Elucidation of the underlying mechanism has provided
opportunities to develop an efficient EphA3 targeting mechanism that is based
on increased affinity and accelerated ephrinA5 uptake as consequence of this
unique activation mechanism. On a genetic level, novel oligonucleotide
analogues known as Peptide Nucleic Acids (PNAs) were analysed for their
ability to sterically inhibit EphA3 DNA transcription and suggest a dosedependent
downregulation of EphA3 expression, in malignant melanoma cells.
Combined, ephrinA5, the anti-EphA3 MAb (IIIA4) and PNA, offer the possibility to investigate the specific machinery involved in Eph receptor expression and
signalling for the specific targeting of EphA3 expressing tumour cells.
33
Pugach, Pavel. "The evolutionary response of the HIV-1 ENV complex to selection pressures in vitro /." Access full-text from WCMC:, 2007. http://proquest.umi.com/pqdweb?did=1428842531&sid=4&Fmt=2&clientId=8424&RQT=309&VName=PQD.
Full text
34
Hudson, Alan Leslie. "Characterisation and comparative autoradiography of #alpha#â†2-adrenoceptors and Iâ†2-sites in mammalian brain." Thesis, University of Bristol, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388036.
Full text
35
Cowie, Philip David. "Analysis of the effects of disease-associated variation within a cis-regulatory element of the CNR1 locus on CNR1 promoter dynamics." Thesis, University of Aberdeen, 2014. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=225652.
Full textAbstract:
Genetic variation within the cannabinoid 1 receptor (CB1R) locus (CNR1) has been repeatedly associated with drug addiction pathologies. Genomic annotation of CNR1 indicates the vast majority of this genetic variation likely results in altered transcriptional regulation of the CNR1 gene as a mechanistic link to the disease phenotype. There is a lack of information describing the regulation of CNR1 transcription and the potential impact of disease-associated variation within the CNR1 locus on its transcriptional regulation. This study investigates the impact of an evolutionary conserved regulatory region of CNR1, termed ECR1, and the disease-associated variation contained within, on the transcriptional activity of the cognate CNR1 promoter region. Reporter assays conducted in primary hippocampal cells demonstrate that CNR1 promoter exhibits variable transcriptional activity during periods of CB1R signalling and cell depolarisation. Coupled to allelic variants of ECR1, the CNR1 promoter shows significant changes in transcriptional activity under resting conditions indicating that disease-associated variation within ECR1 may decrease CNR1 transcription. Further, alleles of ECR1 can drive allele-specific transcriptional responses from the CNR1 promoter during periods of CB1R stimulation and cell depolarisation. The results highlight the potential for disease-associated regulatory variation of the CNR1 locus to create stratified transcriptional responses to specific cell signalling scenarios and putatively to clinical strategies employing pharmacological agents. Furthermore, investigation of DNA-protein interactions at the allelic ECR1 region demonstrate that disease-associated variation within ECR1 alters DNA-protein interactions within the nucleus consistent with a decrease in transcriptional activity in the disease-associated allele variant. Collectively the current work supports the hypothesis that disease-associated variation within the ECR1 regulatory region of the CNR1 locus has the capacity to significantly impact on CNR1 promoter transcriptional activity. It is posited that allele-specific transcriptional effects may have a major impact on the susceptibility of individuals to drug addiction or on responses to clinical pharmacological treatments.
36
Agnes, Richard S. "New paradigm for drug design: Design and synthesis of novel biologically active peptides that are agonists at opioid receptors and antagonists at cholecystokinin receptors." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/280340.
Full textAbstract:
We now know from genomics that many disease states lead to changes in expressed proteins (adaptation/plasticity). Therefore, drug design and discovery based on normal states and single targets often is inadequate or even counter-indicated. Therefore, the "system changes" that have occurred must be considered in any treatment for the disease. Such "systems changes" are clearly evident in neuropathic pain where opioids can actually heighten pain. In these pain states there are increased levels of neurotransmitters such as cholecystokinin (CCK) in which both the peptides and their receptors are increased in pain states. To effectively treat diseases involving "systems changes" a new paradigm for the design of compounds was proposed. In this new approach single peptide or peptidomimetic molecules are designed to interact with multiple receptor targets. For the treatment of pain, a series of linear and cyclic peptides and peptidomimetics were designed based on the overlapping pharmacophores of opioid and CCK ligands. The CCK/opioid analogues were synthesized and evaluated for their biological activities. Several of the CCK/opioid analogues were found to simultaneously interact with opioid receptors as agonists and CCK receptors as antagonists. In addition, the lead compounds have been tested in several pain models and were found to be promising in the treatment of neuropathic pain. Further, the structure-activity relationships of these novel peptides have provided new insights into the requirements for binding and bioactivity at opioid and CCK receptors, as well as the overlapping pharmacophores of CCK and enkephalin.
37
Shah, Bhavik P. "Targeting Fat-Sensitive Pathways In Enteroendocrine Cells Using Nanoparticle-Mediated Drug Delivery." DigitalCommons@USU, 2009. https://digitalcommons.usu.edu/etd/432.
Full textAbstract:
The current epidemic of obesity has been linked to an increase in fat intake associated with the Western diet. Nutrient-induced stimulation of enteroendocrine cells in the small intestine leads to the release of hormones that contribute to satiety and the control of food intake. In particular, ingested fat, specifically in the form of free fatty acids, is potent activator of enteroendocrine cells in the proximal small intestine. However, the underlying signaling cascade that free fatty acids initiate in these enteroendocrine cells, which leads to secretion of satiety hormones, is not known. In general, my research is focused on identifying nutrient-responsive pathways in enteroendocrine cells involved with the release of satiety signals and using this information to begin to develop novel drug delivery strategies to reduce food intake. In general, my results revealed that activation of the fatty acid receptor GPR120 was ecessary for the linoleic acid-induced intracellular calcium rise, a necessary precursor for hormone release. Using patch clamp recording, I discovered that linoleic acid activated enteroendocrine cells by inducing membrane depolarization, a process requiring the calcium-activated, monovalent cation permeable channel TRPM5, which is activated downstream of GPR120. To validate the unexpected finding that TRPM5 was involved in fattyacid signaling, I performed experiments using bitter compounds, whose transduction pathway is known to involve TRPM5. Enteroendocrine cells express the bitter taste receptors and release cholecystokinin in response to bitter stimuli, suggesting the probable role of gut in initiation of protective behavior against ingestion of potentially harmful substances. Armed with the data on the specifics of the fatty acid transduction, I performed experiments using nanoparticles to determine their utility for delivering pharmaceuticals specifically to the enteroendocrine cells. I fabricated and characterized PLGA nanoparticles and performed intracellular uptake studies in order to optimally delivery payloads inside cells. Finally, I validated their use by using cell-based assays to determine the effects of internalized PLGA nanoparticles on ion channels and signaling pathways involved in CCK release. Taken together, this dissertation research has identified the signaling pathways (pharmacological targets) involved in fatty acid-mediated satiety hormone release and validated the potential therapeutic use of nanoparticle-mediated drug delivery for the eventual control of food intake.
38
Smith, Katherine Ann. "Are C. elegans receptors useful targets for drug discovery: Identification of genes encoding seven potential biogenic amine receptors in the parasitic nematode Brugia malayi and pharmacological comparison of tyramine receptor homologues from Caenorhabditi." University of Toledo / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1170202762.
Full text
39
Gallo, María 1989. "Cell-penetrating peptides as drug shuttles for pain management and other therapeutic applications." Doctoral thesis, TDX (Tesis Doctorals en Xarxa), 2021. http://hdl.handle.net/10803/672621.
Full textAbstract:
This thesis focuses on one of the biggest challenges facing drug discovery field: the efficient targeted delivery of therapeutic compounds, and how cell-penetrating peptides (CPPs) acting as drug delivery vectors can overcome pharmacokinetic issues and poor access to difficult targets, such as the central nervous system (CNS).
Specifically, we designed and developed an optimized, oral active, CPP-linked peptide-based disruptor targeting cannabinoid CB1 and serotonin 5HT2A receptor heterodimer, which allows medical use of cannabinoids to fight pain while avoiding memory impairment side effects.
Similarly, we successfully disturbed the adenosine A2A receptor homodimerization by coupling an interfering peptide to a modified cyclic CPP, as a promising strategy for treatment of CNS disorders.
Following also CPP-conjugation, we managed to considerably increase cellular uptake into Leishmania cells of paromomycin, a low bioavailable anti-parasitic drug.
Altogether, this work reinforces CPPs relevance as drug carriers and provides valuable insights into CPPs design, optimization, validation and coupling strategies.Esta tesis se centra en uno de los mayores desafíos que enfrenta el campo del descubrimiento de fármacos: la administración dirigida y eficiente de compuestos terapéuticos; y cómo los péptidos penetrantes de células (CPP), actuando como vectores de liberación, pueden sobreponerse a los problemas farmacocinéticos y el acceso deficiente a objetivos difíciles como el sistema nervioso central (SNC). En particular, diseñamos y desarrollamos un disruptor optimizado, oralmente activo, basado en péptidos y ligado a un CPP, dirigido al heterodímero del receptor de cannabinoide CB1 y serotonina 5HT2A; que permite el uso médico de los cannabinoides para combatir el dolor y evitar los efectos secundarios de deterioro de la memoria. De manera similar, alteramos con éxito la homodimerización del receptor de adenosina A2A utilizando un péptido interferente acoplado a un CPP cíclico modificado, como estrategia prometedora para la exploración de trastornos del SNC. También tras la conjugación con un CPP, logramos aumentar considerablemente la captación celular en células de Leishmania de la paromomicina, un fármaco antiparasitario de baja biodisponibilidad. En conjunto, este trabajo refuerza la relevancia de los CPPs como portadores de medicamentos y proporciona información valiosa sobre el diseño, optimización, validación y las estrategias de acoplamiento de los CPPs.
40
Qi, Huiling. "Modulation of folate receptor B for drug targeting in acute myelogenous leukemia." Connect to full-text via OhioLINK ETD Center, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=mco1147304406.
Full textAbstract:
Thesis (Ph.D.)--Medical University of Ohio, 2005."In partial fulfillment of the requirements for the degree of Doctor of Philosophy in Medical Sciences." Major advisor: Manohar Ratnam. Includes abstract. Document formatted into pages: iv, 158 p. Title from title page of PDF document. Title at ETD Web site: Modulation of folate receptor beta for drug targeting in acute myelogenous leukemia. Non-Latin script record Bibliography: pages 67-70, 106-109, 127-156.
41
Newton, Claire Louise. "Hetero-dimer formation between D₂ and D₃ dopamine receptors : functional implications for antipsychotic drug action." Thesis, University of Reading, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.446213.
Full text
42
Monaghan, Amy Elizabeth. "The amino terminal domain of steroid hormone receptors as a novel drug target : identification of small molecule inhibitors." Thesis, University of Aberdeen, 2016. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=230709.
Full textAbstract:
Steroid hormone receptors (SHRs) are well validated therapeutic targets in a number of diseases. Current therapies competitively antagonise the ligand binding domain (LBD), blocking activation of the receptor and downstream signalling pathways. However cross-reactivity can be seen amongst the antagonists of different SHRs eliciting unwanted side effects. Additionally the acquisition of resistance to current therapies in diseases such as prostate cancer limits their use. The amino-terminal domain (NTD) of SHRs provides an alternative target for antagonism by allowing potential therapies to block receptor transactivation and inhibit interactions with co-activator proteins. Reduced homology between different SHR NTDs also increases the specificity of drug interactions. However development of targeted therapies using rational drug design has been hindered by its intrinsically disordered structure. Establishing cell lines which stably express a SHR responsive reporter gene alongside variants of SHRs lacking the LBD provides a method by which small molecules specifically targeting the NTD of each receptor can be identified. This assay has been designed to overcome the barriers to drug discovery that are presented by an intrinsically disordered protein. The project follows the design, development, optimisation and implementation of a high throughput screening assay with the potential to identify novel small molecule inhibitors of SHRs. The applications of these inhibitors are highlighted throughout, with specific reference to their potential to inhibit the androgen receptor in prostate cancer.
43
Bulka, Aleksandra. "Genetic differences in neuropathy and opioid responses in rats /." Stockholm, 2003. http://diss.kib.ki.se/2003/91-7349-753-3/.
Full text
44
Aguinaga, Andrés David. "Interacción molecular y funcional entre receptores involucrados en la ingesta de alimentos y el consumo de drogas de abuso." Doctoral thesis, Universitat de Barcelona, 2017. http://hdl.handle.net/10803/406073.
Full textAbstract:
Actualmente en la comunidad científica aún existe debate acerca de la heteromerización entre receptores GPCR y el papel que esta tiene en la señalización y funcionalidad celular. Tradicionalmente estos receptores han sido considerados entidades monoméricas, No obstante, en las últimas décadas han sido obtenidos resultados que apoyan la teoría de que estos receptores pueden formar homómeros y heterómeros.
Entender cómo funcionan los receptores al formar complejos heteroméricos con otros receptores, u otras proteínas, es de vital importancia para dar explicación a muchos mecanismos fisiológicos, así como para el diseño de nuevos fármacos. Entender cómo se establecen las modulaciones entre unos receptores y otros posibilitará también en un futuro el desarrollo de tratamientos preventivos para distintos trastornos psicológicos, como la adicción a drogas.
Uno de los principales objetivos de esta tesis ha sido estudiar y aportar nuevos datos para entender el funcionamiento de la adicción a sustancias psicoestimulantes, concretamente, la cocaína. En esta Tesis ha sido puesto de manifiesto la importancia de la modulación que pueden ejercer las interacciones que afectan a los GPCR en relación a la adicción a cocaína. En primer lugar, ha sido demostrada la capacidad de los receptores sigma-1 y sigma-2 para interaccionar con distintos GPCR, los receptores D1 y D2 de dopamina, el heterómero de receptores CRF1R-OX1R o el receptor de grelina, GHS-R1a. La cocaína, al unirse a los receptores sigma, modifica, en todos los casos, la señalización normal inducida por estos GPCRs, contribuyendo a la adicción a la droga de abuso, provocando una recaída en el comportamiento de búsqueda de cocaína en respuesta a una situación de estrés o bloqueando de la sensación de apetito tras el consumo de la droga.
Al producirse las interacciones, los complejos formados pueden ajustar su actividad a distintos ambientes o necesidades celulares que los receptores, por sí solo, no serían capaces de detectar. En esta misma línea está el papel que juegan las proteínas sensoras de calcio en la modulación de la actividad de algunos GPCR. El calcio es un mensajero imprescindible, las fluctuaciones en los niveles de este ion pueden ir desde niveles submicromolares hasta milimolares, siendo uno de los mecanismos de regulación más importantes en la célula. Distintas concentraciones de calcio pueden inducir diferentes señalizaciones a través de un mismo heterómero de GPCR. Ha sido descrita la capacidad del heterómero A2A-D2 para unir diferentes proteínas sensoras de calcio, NCS-1 y calneurona-1, las cuales tienen diferentes afinidades por el ion calcio y regularan el heterómero de manera distinta en función de las bajas (unión de NCS-1) o altas (unión de calneurona-1) concentraciones de calcio celular, dándole versatilidad a un mismo heterómero.
Por último, han sido investigadas las interacciones entre GPCR a nivel estructural con la finalidad de elucidar las regiones de los receptores implicadas en la formación de los heterómeros. Ha sido propuesto un nuevo modelo estructural tetramérico formado por un homodímero de receptores A1 de adenosina y un homodímero de receptores A2A de adenosina. En este complejo son las regiones transmembrana TM4/5 las responsables de la homodimerización y las regiones TM5/6 las responsables de la heteromerización, formando una estructura romboidal a en la que se acoplan dos proteínas G, Gi y Gs. Ha sido demostrada la importancia de la comunicación entre las proteínas G en un heterómero de GPCR, explicando, por primera vez, el mecanismo por el que el heterómero A1R-A2AR actúa como sensor de la concentración de adenosina pudiendo dar respuestas opuestas, vía proteína Gi o Gs, en función de la concentración extracelular de adenosina.Currently in the scientific community there is still debate about the heteromerization between GPCR and the role it has in cell signaling and functionality. Traditionally, these receptors have been considered monomeric entities. However, in recent decades new results have been obtained supporting the theory that these receptors can form oligomers. Understand how receptors interact when forming heteromeric complexes is crucial to explain many physiological mechanisms as well as in the design of new drugs. To elucidate how the modulation between receptors works will also enable the development of treatments for different disorders, such as drug addiction. One of the main objectives of this Thesis has been to contribute with new data to understand the underlying mechanisms of psychostimulant substances addiction. The importance of the modulation on GPCR exerted by heteromers in relation to cocaine addiction has been shown. The ability of the cocaine-binding receptors sigma-1R and sigma-2R to interact with different GPCRs, dopamine D1R and D2R, CRF1R-OX1R or GHS-R1a-GHS-R1b heteromers, has been demonstrated. Cocaine, when bound to the sigma receptors modifies the normal signaling induced by these GPCRs, contributing to drug addiction, relapse in cocaine seeking behavior or blocking the appetite sensation after the drug consumption. When interactions occur, the formed complexes can adjust their functionality to different cellular environments that these receptors, by themselves, would not be able to detect. One example is the modulating role exerted by the calcium sensing proteins on certain GPCR. Calcium is one of the most important regulatory mechanisms in the cell. Different calcium concentration may induce different signaling through the same GPCR heteromer. The ability of heteromers to bind different calcium sensors has been described. These calcium sensors have different affinities for the calcium ion and regulate differently the heteromer, depending on the low or high calcium concentrations, thus providing versatility to the complex. Finally, interactions between GPCRs at the structural level have been investigated in order to elucidate the receptor domains involved in the heteromers formation. A new tetrameric structural model formed by A1R-A1R-A2AR-A2AR adenosine receptors has been proposed, forming a rhomboidal structure in which two G proteins, Gi and Gs, are coupled. It has also been explained the mechanisms by which this heteromer acts as a adenosine concentration sensor giving opposite responses, via Gi or Gs, depending on the extracellular adenosine concentration.
45
Stuart, Emma, and n/a. "Therapeutic potential of SERM and EGCG drug combinations for the treatment of basal-like breast cancer." University of Otago. Department of Pharmacology & Toxicology, 2009. http://adt.otago.ac.nz./public/adt-NZDU20090708.090405.
Full textAbstract:
Basal-like breast cancer represents a subgroup of mammary cancers associated with a particularly poor prognosis, as they are refractory to current targeted therapies employed for the treatment of breast cancer. In this work I aimed to explore the therapeutic potential of selective estrogen receptor modulators (SERMs), a targeted breast cancer treatment, in combination with epigallocatechin gallate (EGCG), for the treatment of basal-like breast cancer, using MDA-MB-231 cell as an in vitro model of the disease. A significant reduction in MDA-MB-231 cell number and a significant increase in cytotoxicity was observed following treatment with 25 [mu]M of EGCG in combination with 1 [mu]M of 4-hydroxytamoxifen (4-OHT) (EGCG+4-OHT) or 4 [mu]M of raloxifene (EGCG+Ral) over a 36 h time course. However, these effects were not resolved in time, with an increase in G₁-phase cell cycle arrest. Changes in the metabolism of EGCG were dismissed as a possible mechanism through which the combination treatments may be eliciting the cytotoxicity. Changes in the expression and phosphorylation of various signaling proteins, important for the proliferation and survival of basal-like breast cancer, were investigated through Western blotting.
Interestingly, the two combination treatments produced very similar results; reductions in the phosphorylation of EGFR and AKT occurred after 6, 12, and 18 h with EGCG+4-OHT and 6, 12, 18 and 24 h with EGCG+Ral, while a reduction in S6K phosphorylation was observed following 6, 12, 18 and 24 h of both combination treatments. Interestingly, both SERMs contributed significantly to the net reduction in S6K phosphorylation, induced by the combination treatments. Both combination treatments were also associated with a significant increase in the phosphorylation and total expression of stress activated protein kinases, p38 and JNK1/2 following 12, 18 and 24 h of treatment. As changes were observed at an intracellular signaling level, the effect of the combination treatments were investigated at the transcriptomic level after 18 h of treatment, using human oligonucleotide microarrays. This transcriptomic analysis revealed that both combination treatments reduced the transcript expression of five enzymes involved with cholesterol synthesis, which was confirmed through qRT-PCR. Cholesterol is an important component of the plasma membrane and is critical for the transduction of extracellular signals. Furthermore, both combination treatments induced the transcriptomic expression of the zinc coordinating metallothionein (MT) proteins. This was associated with an increased nuclear localization of MTF-1, the transcription factor responsible for MT expression, after 6, 12 and 18 h of both combination treatments. Finally, nuclear Western blotting of the NF-[kappa]B subunit, p65, revealed that both combination treatments reduced the nuclear localization of NF-[kappa]B following 6, 12 and 18 h. In collating this data, it appears that the combination treatments of EGCG+4-OHT and EGCG+Ral are inducing cytotoxicity through various mechanisms, including reduced cellular signaling through EGFR, AKT and S6K, increased stress signaling through JNK1/2 and p38 and altered gene expression of MTs and enzymes involved with cholesterol synthesis. Therefore, the combination treatment of EGCG+SERMs exhibits therapeutic potential in MDA-MB-231 cells, a model of basal-like breast cancer.
46
Imre. "Group II metabotropic glutamate (mGlu2/3) receptors potential drug targets for the treatment of schizophrenia and anxiety? /." [S.l. : [Groningen : s.n.] ; University Library Groningen] [Host], 2006. http://irs.ub.rug.nl/ppn/297586998.
Full text
47
Zijlstra, Sytse. "Positron emission tomography of cerebral dopamine receptors synthesis and evaluation of agonists and drug response in schizophrenia /." [S.l. : [Groningen : s.n.] ; University Library Groningen] [Host], 1995. http://irs.ub.rug.nl/ppn/298194147.
Full text
48
Panarello, Silvia. "Photoswitchable allosteric ligands to modulate metabotropic glutamate receptors." Doctoral thesis, Universitat de Barcelona, 2021. http://hdl.handle.net/10803/673024.
Full textAbstract:
Photopharmacology has the main purpose to allow the control of protein activity with light. The most exploited strategy used to achieve this objective is the freely diffusible photopharmacology and it is based in the use of photosensitive ligands. These ligands are small bioactive molecules, which include a part of their structure (i.e. photoswitch) that can experience molecular changes upon illumination with a determined wavelength of light. These ligands can freely diffuse and they can be applied with systems expressing native proteins.
Azobenzene is the most common photoswitch used in photopharmacology and it can switch with near UV light from the flat and long trans isomer to a shorter bent cis configuration. The reverse photoisomerization can be achieved either with visible light or thermally with light. Thus, if we include azobenzene in the molecular scaffold of a ligand by means of a replacement of a particular moiety (azologization), we can obtain new azo compounds that will resemble to the original ligand, but their structural shape will dramatically changes upon illumination (photoisomerization). Therefore, the two possible isomers will have distinct binding modes to the target protein and will lead to different protein activities under different light conditions, which is known as photoswitching.
Metabotropic Glutamate Receptors (mGluRs) belong to the class C/Glutamate family of G Protein-Coupled Receptors and control many neuronal and glial functions. mGlu receptors are endogenously activated by glutamate, which is the major excitatory neurotransmitter in the central nervous system (CNS), but they can also be activated or inactivated by allosteric modulators. They are usually considered better drug candidates than the orthosteric ligands because usually highly specific for a receptor and able to modulate the activity of a given receptor without blocking endogenous ligand binding.
First of all, we designed and synthesized three families of compounds, using an azo-replacement strategy, to obtain photoswitchable allosteric modulators with possible NAM activity in mGlu5 in the cis isomers, while in the trans form they are inactive. This behavior is easily controlled by illuminating with different wavelengths and it is reversible in vitro. All the three families were inactive as NAMs, but some results suggest that the compounds could act as mGlu5 PAMs in trans form. Studies are continuing in this direction (Chapter 1).
Next, we carry out the design and synthesis of compounds to improve PAM activity at the mGlu4 receptor and increase selectivity over the other group III mGluRs of at least one azo benzene candidate with a structure similar to Optogluram, the first photoswitchable positive allosteric modulator for the mGlu4 receptor. We obtained Optogluram-2 with good pharmacological potency and improved the photoisomerization properties. Under 380 nm light, the potency of Optogluram-2 is significantly reduced. The change in photoinduced potency observed is greater in Optogluram-2 than in Optogluram. Optogluram-2 has similar potency to Optogluram but is more selective for mGlu4 both on the receptors of the same group III as on the other mGluRs. All this indicates that Optogluram-2 can induce an improved activated/deactivated profile change as well as have an optimal selectivity for more complex assays, such as in vivo assays (Chapter 2).
Additionally, we synthesized two series of compounds to find the first photoswitchable compound to selectively enable optical control of the endogenous mGlu1 receptor. Photoglurax-1 arose as a PAM of mGlu1
with micromolar potency in the trans isomer. Under 380nm light, the potency is significantly reduced. Photoglurax-1 turned out to be an equipotent mGlu4 PAM and therefore its general profile is not suitable for in vivo translation as a possible mGlu1 PAM tool compound. However, a dual mGlu1/mGlu4 PAM activity could be intriguing for an antipsychotic agent, since mGlu4 PAM activity can alleviate catalepsy, a major adverse event with standard antipsychotic drug treatment. In contrast, Photoglurax-2 acts as a mGlu1 PAM and does not show any observable allosteric effect on mGlu4 or activity on mGlu5, and therefore Photoglurax-2 represents a potential in vivo photoswitchable PAM mGlu1 tool compound. Reversible monitoring of mGlu1 activity obtained with light can be very advantageous in studying the pharmacological and physiological implications of mGlu1 in many diseases with unprecedented precision (Chapter 3).
Finally, we designed and synthesized a family of novel photoswitchable azoheteroarenes as mGlu1 NAMs with an active trans isomer and an inactive cis isomer to reversibly inactivate the function of the mGlu1 receptor. The potencies of the trans configurations of some compounds of the family are in the micromolar range . Unfortunately, after 400 nm illumination the results were inconclusive due to artifacts that could originate from a possible toxicity of cis azo compounds. More experiments should be done with cells that do not express mGlu1 and also changing the light system to corroborate eventual toxicity (Chapter 4). Likewise, we use some of these compounds in their trans form, therefore without applying light, as tools to expand the knowledge about the nature of the intermediate states induced by mGlu receptor agonists in studies of fluorescence conformational dynamics. Analysis of the effect of mGlu1 NAMs on receptor conformational changes is reported in Chapter 4.Los receptores metabotrópicos de glutamato (mGlu) son GPCRs distribuidos a través del CNS y se consideran dianas farmacológicas para trastornos neurológicos, tales como el dolor neuropático y la enfermedad de Parkison, entre otras. En primar lugar, diseñamos y sintetizamos tres familias de compuestos, utilizando una estrategia de azo- reemplazo, para obtener moduladores alostéricos de GPCR fotoconmutable con posible actividad NAM en mGlu5 en los isomeros cis, mientras que en la disposición trans son inactivos. Este comportamiento se controla fácilmente con iluminación con diferentes longitudes de onda y es reversible in vitro. Ninguna familia resultò activa como NAMs, pero algunos resultados sugieren que los compuestos podrían actuar como PAMs mGlu5 en forma trans. La investigación continúa siguiendo esta dirección (Capítulo 1). Seguidamente, realizamos el diseño y sintesis de compuestos para mejorar la actividad de PAM en el receptor mGlu4 y aumentar la selectividad sobre los otros mGluR del grupo III de al menos un candidato a azobenceno con estructura similar a Optogluram, el primer modulador alostérico positivo fotoconmutable para el receptor mGlu4. Obtuvimos Optogluram-2 con buena potencia farmacologica y mejoramos las propriedades de fotoisomerizacion. Bajo una luz de 380 nm, la potencia de Optogluram-2 se reduce significativamente. El cambio de potencia fotoinducido observado es mayor en Optogluram-2 que en Optogluram.Optogluram-2 tiene potencia parecida a Optogluram pero es màs selectivo para mGlu4 tanto sobre los receptores del mismo grupo III como sobre los demas. Todo esto indica que Optogluram-2 puede inducir un cambio de perfil activado/desactivado mejorado asì como tener una selectividad optimal para ensayos más complejos, como los ensayos in vivo (Capítulo 2). Sintetizamos dos series para encontrar el primer compuesto fotoconmutable para habilitar selectivamente el control óptico del receptor mGlu1 endógeno. Photoglurax-1 surgió como un PAM de mGlu1 con potencia micromolar en el isómero trans. Bajo una luz de 380 nm, la potencia se reduce significativamente. Photoglurax- 1 resultó ser un mGlu4 PAM equipotente y por eso su perfil general no es apropiado para una traducción in vivo como una posible herramienta molecular mGlu1 PAM. Sin embargo, una actividad dual mGlu1/mGlu4 PAM podría ser intrigante para un agente antipsicótico,ya que la actividad mGlu4 PAM puede aliviar la catalepsia, un evento adverso importante con el tratamiento estándar con fármacos antipsicóticos. En cambio, Photoglurax-2 actúa como un PAM mGlu1 y no muestra ningún efecto alostérico observable en mGlu4 ni actividad en mGlu5 y por lo tanto Photoglurax-2 representa una potencial herramienta molecular PAM mGlu1 fotoconmutable in vivo. El control reversible de la actividad de mGlu1 obtenido con luz puede ser muy ventajoso para estudiar las implicaciones farmacológicas y fisiológicas de mGlu1 en muchas enfermedades con una precisión sin precedentes (Capítulo 3). Finalmente, intentamos diseñar y sintetizar una familia de novedosos azoheteroarenos fotoconmutables como NAMs de mGlu1 con un isomero trans activo y un isomero cis inactivo para inactivar reversiblemente la función del receptor mGlu1. Las potencias de las configuraciones trans de algunos compuestos de la familia estan en el rango de micromolaridad. Desafortunadamente, tras una iluminación de 400 nm los resultados fueron no concluyentes debido a artefactos que podrían originarse a partir de una posible toxicidad de los compuestos cis azo. Se deben realizar más experimentos con células que no expresen mGlu1 y cambiando tambien el sistema de luz para comprobar si se trata de toxicidad (Capítulo 4). Asimismo, utilizamos algunos de estos compuestos en su forma trans, por lo tanto sin aplicar luz, como herramientas para ampliar el conocimiento sobre la naturaleza de los estados intermedios inducidos por agonistas de los receptores mGlu en estudios de dinámica conformacional de fluorescencia. El análisis del efecto de los NAMs de mGlu1 sobre los cambios conformacionales del receptor están reportados en el Capítulo 4. En resumen, encontramos como obtener un interruptor molecular entre varias actividades farmacologicas. Ademàs, demostramos que la fotofarmacologia presenta ventajas respecto a la farmacologia convencional, ya que permite ajustar la activacion del receptor con luz.
49
Regna, Kimberly. "Insights into vector control through the modulation of An. gambiae G protein-coupled receptors." Thesis, Boston College, 2015. http://hdl.handle.net/2345/bc-ir:104637.
Full textAbstract:
Thesis advisor: Marc A.T. MuskavitchMalaria is a life-threatening infectious disease caused by inoculation of the apicomplexan Plasmodium parasite into vertebrate hosts. Transmission of the parasite is mediated by the Anopheles mosquito, which has the capacity to efficiently transmit the parasite from host to host, as the disease vector. There are many factors that make anopheline mosquitoes competent vectors for disease transmission. The hematophagous (blood-feeding) behavior of the female mosquito is one of most fundamental factors in physical transmission of parasites, because the ingestion of blood from an infected host allows parasite entry into the mosquito and the completion of parasite sexual reproduction. In addition to this blood-feeding behavior, there are a host of biological (i.e., parasite replication) and behavioral factors (i.e., mosquito chemosensation, host preference) that contribute to the high vectorial capacity of these vector species. There are over four hundred Anopheles species worldwide, approximately forty of which are considered epidemiologically critical human malaria vectors. Anopheles gambiae, the primary vector in malaria-endemic sub-Saharan Africa, is responsible for the largest number of malaria cases in the world and is therefore one of the most important vectors to study and target with control measures. Currently, vector-targeted control strategies remain our most effective tools for reduction of malaria transmission and incidence. Although control efforts based on the deployment of insecticides have proven successful in the past and are still widely used, the threat and continuing increases of insecticide resistance motivate the discovery of novel insecticides. In this thesis, I provide evidence that G protein-coupled receptors (GPCRs) may serve as “druggable” targets for the development of new insecticides, through the modulation of developmental and sensory processes. In Chapter II, “A critical role for the Drosophila dopamine 1-like receptor Dop1R2 at the onset of metamorphosis,” I provide evidence supporting an essential role for this receptor in Drosophila melanogaster metamorphosis via transgenic RNA interference and pharmacological methods. In An. gambiae, we find that the receptor encoded by the mosquito ortholog GPRDOP2 can be inhibited in vitro using pharmacological antagonists, and that in vivo inhibition with such antagonists produces pre-adult lethality. These findings support the inference that this An. gambiae dopamine receptor may serve as a novel target for the development of vector-targeted larvicides. In Chapter III, “RNAi trigger delivery into Anopheles gambiae pupae,” I describe the development of a method for injection directly into the hemolymph of double strand RNA (dsRNA) during the pupal stage, and I demonstrate that knockdown of the translational product of the SRPN2 gene occurs efficiently, based on reductions in the levels of SRPN2 protein and formation of melanized pseudo-tumors, in SRPN2 knockdown mosquitoes. This method was developed for rapid knockdown of target genes, using a dye-labeled injection technique that allows for easy visualization of injection quality. This technique is further utilized in Chapter IV, “Uncovering the Role of an Anopheles gambiae G Protein-Coupled Receptor, GPRGR2, in the Detection of Noxious Compounds,” where the role for GPRGR2 in the detection of multiple noxious compounds is elucidated. We find that pupal stage knockdown of this receptor decreases the ability of adult Anopheles gambiae to identify multiple noxious compounds. While these findings provide a strong link between GPRGR2 and a very interesting mosquito behavior, they may also provide opportunities to develop better field-based strategies (i.e., insecticides baited traps) for vector control. The goal of this thesis is to understand the functional roles of selected mosquito GPCRs that may serve as targets for the development of new vector-targeted control strategies. Exploiting these GPCRs genetically and pharmacologically may provide insights into novel vector control targets that can be manipulated so as to decrease the vectorial capacity of An. gambiae and other malaria vectors in the field, and thereby decrease the burden of human malaria
Thesis (PhD) — Boston College, 2015
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Biology
50
Xiang, Hong. "Alpha₁-adrenoceptor-mediated phosphoinositide breakdown and inotropic responses in right ventricles of streptozotocin-diabetic rats." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/31036.
Full textAbstract:
The morbidity of and the mortality from cardiac disease are higher in diabetic patients. Clinical and experimental evidence suggests that diabetes-induced changes at the level of myocardium can, at least partially, contribute to these cardiac problems. The mechanism(s) involved in this diabetic cardiomyopathy is still unclear, but one defect appears to occur in the alpha₁-adrenoceptor system. Altered myocardial sensitivity and responsiveness to alpha₁-adrenoceptor agonists have been reported in experimental diabetes mellitus. Stimulation of alpha₁-adrenoceptors is known to produce a positive inotropic effect and has been recently shown to stimulate the hydrolysis of phosphoinositides. To evaluate the possibility that the changes in the inotropic responsiveness to alpha₁-adrenoceptor stimulation in the diabetic heart could be linked to altered alpha₁-adrenoceptor-stimulated
phosphoinositide turnover and further to the development of diabetic cardiomyopathy, we studied contractility and receptor-stimulated phosphoinositide turnover following norepinephrine (in the presence of propranolol) stimulation in right ventricles from male Wistar rats (200-225 g) which were made diabetic with streptozotocin (55 mg/kg, i.v.). Rats were sacrificed six weeks after the induction of diabetes. Diabetic rats were characterized by decreased body weight gain, hypoinsulinemia, hyperglycemia and hyperlipidemia.
Stimulation of alpha₁-adrenoceptors by norepinephrine (in the presence of propranolol) in right ventricles resulted in the formation of inositol monophosphate (measured with a radioisotope method) and inositol 1,4,5-trisphosphate (measured with an inositol 1,4,5-trisphosphate protein binding assay kit) in a time- and concentration-dependent manner in both control and diabetic rats. The increase in inositol 1,4,5-trisphosphate levels preceded the increase in the alpha₁-adrenoceptor-mediated positive inotropic effect. Diabetic hearts showed a greater maximum inotropic response to norepinephrine stimulation and also had a higher inositol 1,4,5-trisphosphate levels. However, with the radioisotope method, a decreased inositol monophosphate formation was shown in diabetic hearts compared with controls.
Omega-3 fatty acids supplementation (Promega[symbol omitted], 0.5 ml/kg/day) had no significant effect on the changes in norepinephrine-stimulated inositol monophosphate formation in diabetic hearts.
In the presence of the cyclooxygenase inhibitor indomethacin or the thromboxane synthetase inhibitor imidazole, the norepinephrine-stimulated positive inotropic effect and inositol 1,4,5-trisphosphate formation were significantly increased in control hearts, but were unaltered in the hearts from diabetics. The addition of the prostacyclin synthetase inhibitor tranylcypromine reduced the norepinephrine-stimulated positive inotropic effect and
inositol 1,4,5-trisphosphate formation only in diabetic hearts and had no effect in the controls.
While inositol 1,4,5-trisphosphate may be able to mediate only transient inotropic effects produced by alpha₁-adrenoceptor stimulation, diacylglycerol may provoke a sustained positive inotropic effect by activating slow Ca²⁺ channels through stimulation of protein kinase C. Our results showed that the diabetic hearts had a higher protein kinase C activity in the membrane fraction compared with controls and this was accompanied by a decrease in cytosolic protein kinase C activity.
The present study suggests that the increases in inositol 1,4,5-trisphosphate levels and the membrane fraction protein kinase C activity may be implicated in the increased inotropic responsiveness to alpha₁-adrenoceptor stimulation in the hearts of the streptozotocin-diabetic rats. The increases in inositol 1,4,5-trisphosphate level and protein kinase C activity could induce Ca²⁺ overload in the diabetic heart which might be involved in the development of diabetic cardiomyopathy. The results from the omega-3 fatty acid study indicate that the changes in cardiac alpha₁-adrenoceptor-mediated inositol phosphates formation cannot contribute to the previously described improved cardiac function of omega-3 fatty acid-treated streptozotocin-diabetic rats. The nature and physiological significance of the enhanced positive inotropic effect and inositol 1,4,5-trisphosphate formation in the control heart
with the addition of indomethacin and imidazole is still unclear. The effect of tranylcypromine may indicate the participation of prostaglandins in mediating the enhanced alpha₁-inotropic effect of norepinephrine in the diabetic heart.Pharmaceutical Sciences, Faculty of
Graduate