Dissertations / Theses on the topic 'Streptozotocin model'

Diabetes mellitus is a complex disease characterised by chronic hyperglycaemia due to compromised insulin synthesis and secretion, or decreased tissue sensitivity to insulin, if not all three conditions. Endothelial dysfunction is a common complication in diabetes in which endothelium-dependent vasodilation is impaired. The aim of this study was to examine the involvement of TRPV4 in diabetes endothelial dysfunction. Male Charles River Wistar rats (350-450 g) were injected with 65mg/kg streptozotocin (STZ) intraperitoneally. STZ-injected rats were compared with naïve rats (not injected with STZ) or control rats (injected with 10ml/kg of 20mM citrate buffer, pH 4.0-4.5), if not both. Rats with blood glucose concentrations greater than 16mmol/L were considered to be diabetic. As the results revealed, STZ-diabetic rats showed significant endothelial dysfunction characterised by impaired muscarinic-induced vasodilation, as well as significant impairment in TRPV4-induced vasodilation in aortic rings and mesenteric arteries. Furthermore, STZ-diabetic primary aortic endothelial cells (ECs) showed a significant reduction in TRPV4-induced intracellular calcium ([Ca2+]i) elevation. TRPV4, endothelial nitric oxide synthase (eNOS), and caveolin-1 (CAV-1) were also significantly downregulated in STZ-diabetic primary aortic ECs and were later significantly restored by in vitro insulin treatment. Methylglyoxal (MGO) was significantly elevated in STZ-diabetic rat serum, and nondiabetic aortic rings incubated with MGO (100μM) for 12 hours showed significant endothelial dysfunction. Moreover, nondiabetic primary aortic ECs treated with MGO (100μM) for 5 days showed significant TRPV4 downregulation and significant suppression of 4-α-PDD-induced [Ca2+]i elevation, which was later restored by L-arginine (100μM) co-incubation. Incubating nondiabetic aortic rings with MGO (100μM) for 2 hours induced a spontaneous loss of noradrenaline-induced contractility persistence. Moreover, MGO induced significant [Ca2+]i elevation in Chinese hamster ovary cells expressing rat TRPM8 channels (rTRPM8), which was significantly inhibited by AMTB (1-5μM). Taken together, TRPV4, CAV-1, and eNOS can form a functional complex that is downregulated in STZ-diabetic aortic ECs and restored by insulin treatment. MGO elevation might furthermore contribute to diabetes endothelial dysfunction and TRPV4 downregulation. By contrast, MGO induced the loss of contractility persistence, possibly due to MGO's acting as a TRPM8 agonist.

Diabetes is a group of metabolic diseases where the body’s pancreas does not produce enough insulin or does not properly respond to insulin produced, resulting in high blood sugar levels over a prolonged period. There are several different types of diabetes, but the most common forms are type 1 and type 2 diabetes. Type 1 diabetes Mellitus (T1DM) can occur at any age, but is most commonly diagnosed from infancy to late 30s. If a person is diagnosed with type 1 diabetes, their pancreas produces little to no insulin, and the body’s immune system destroys the insulin-producing cells in the pancreas. Those diagnosed with type 1 diabetes must inject insulin several times every day or continually infuse insulin through a pump, as well as manage their diet and exercise habits. If not treated appropriately, it can cause serious complications such as cardiovascular disease, stroke, kidney failure, foot ulcers, and damage to eyes.

During the past decade, researchers have developed artificial pancreas (AP) to ease management of diabetes. AP has three components: continuous glucose monitor (CGM), insulin pump, and closed-loop control algorithm. Researchers have developed algorithms based on control techniques such as Proportional Integral Derivative (PID) and Model Predictive Control (MPC) for blood glucose level (BGL) control; however, variability in metabolism between or within individuals hinders reliable control.

This study aims to develop an adaptive algorithm using Artificial Neural Networks (ANN) based Model Predictive Control (NN-MPC) to perform proper insulin injections according to BGL predictions in diabetic rats. This study is a ground work to implement NN-MPC algorithm on real subjects. BGL data collected from diabetic rats using CGM are used with other inputs such as insulin injection and meal information to develop a virtual plant model based on a mathematical model of glucose–insulin homeostasis proposed by Lombarte et al. Since this model is proposed for healthy rats; a revised version on this model with three additional equations representing diabetic rats is used to generate data for training ANN which is applicable for the identi?cation of dynamics and the glycemic regulation of rats. The trained ANN is coupled with MPC algorithm to control BGL of the plant model within the normal range of 100 to 130 mg/dl by injecting appropriate amount of insulin. The ANN performed well with less than 5 mg/dl error (2%) for 5-minute prediction and about 15 mg/dl error (7%) for 30-minute prediction. In ¬¬addition, the NN-MPC algorithm kept BGL of diabetic rats more than 90 percent of the time within the normal range without hyper/hypo-glycaemia.

Objectives: To date little is known of the interaction between diabetes and sex hormones in the vasculature. A number of studies suggest that premenopausal diabetic women loose their gender based cardiovascular protection. However, there is insufficient evidence to explain the mechanism underlying the loss of this gender based cardioprotection in premenopausal diabetic women. The objectives of this study were to investigate whether there is a gender difference in the aortic endothelial function in · streptozotocin (STZ, 58 mg/kg, iv)-induced diabetic rats, and the potential role of superoxide and cyclooxygenase (COX) metabolites in diabetes-induced vascular dysfunction.

Elevated sympathetic nervous system (SNS) tone contributes to excess cardiac mortality associated with type 2 diabetes mellitus (T2DM). Chronic SNS stimulation has detrimental effects to the heart, in particular, with its cell signaling abilities. (R)-[11C]Rolipram small animal positron emission tomography (PET), an noninvasive nuclear imaging modality, was used to assess phosphodiesterase-4 (PDE4) alterations in a high fat diet (HFD), streptozotocin (STZ) induced model of hyperglycemia in rats. Prior to investigation in the animal model, characterization of (R)-[11C]rolipram small animal PET was completed. (R)-[11C]Rolipram binds specifically to PDE4 in the rat heart demonstrated by competitive blockade with (R)-rolipram with the PDE4 enzyme susceptible to saturation with increasing injected masses of unlabeled rolipram. (R)-[11C]Rolipram cardiac retention was elevated by acute norepinephrine stimulation via desipramine pharmacologic challenge. Quantitative (R)-[11C]rolipram PET was highly reproducible in the heart and presents an ideal avenue to investigate PDE4 alterations. (R)-[11C]rolipram small animal PET did not reveal changes in PDE4 expression and activity in STZ-treated hyperglycemic animals compared to STZ-treated euglycemic and control groups. In vitro measures of PDE4 enzyme expression and activity, with or without desipramine, were also not altered between treatment groups. Although (R)-[11C]rolipram small animal PET does not reveal PDE4 alterations in this animal model of diabetes, its utility to assess PDE4 alterations in other over active SNS pathologies, such as heart failure and obesity, remains.

Thesis submitted in fulfilment of the requirements for the Doctor of Technology: Biomedical Technology In the Faculty of Health and Wellness At the CAPE PENINSULA UNIVERSITY OF TECHNOLOGY, 2012
Diabetes mellitus is a major health problem not only in urban, but also in the rural areas and is diagnosed by the presence of high glucose levels in the blood. Oxidative stress is known to be actively involved in the onset and progression of diabetes and its complications. Antioxidants have important roles in biological systems by scavenging free radicals which may result in oxidative damage of biological molecules such as lipids, proteins and DNA. Red palm oil, originally from the tropical area of Africa, generally consumed as cooking oil, is known to have some beneficial health effects due to the presence of lipid soluble antioxidants such as carotenoids, tocopherols and tocotrienols. It also contains almost an equal proportion of both saturated and unsaturated fatty acids which makes it distinctive from other vegetable oils. Rooibos, on the other hand, is grown in the Cederberg area of the Western Cape in South Africa and it is commonly consumed as a beverage. It contains a complex profile of water soluble antioxidants (flavonoids) and its health promoting potentials have been reported extensively. Some of the flavonoids present in rooibos include aspalathin, nothofagin, quercetin, rutin and orientin. The objective of this research project was to examine the potential beneficial effects of the dietary intake of red palm oil and rooibos on streptozotocin-induced hyperglycaemia and its influence on the antioxidant status and some biochemical parameters in male Wistar rats. The preliminary phase of this study was designed to investigate the biochemical effects of these two plant products at different dosages following consumption for a period of 7 weeks. The preliminary study did not reveal any adverse effects of the different dosages of red palm oil (1 ml, 2 ml and 4 ml) and rooibos (2%, 4% and 6%) on the experimental rats following dietary intake for 7 weeks. However, these natural products showed an improvement in the antioxidant status of the rats at the different doses. Using a single dose each of both plant products from the preliminary study, the main study was performed to investigate the influence of these two plant products singly and in combination on the blood and liver of streptozotocin-induced hyperglycaemic male Wistar rats. In the main study, streptozotocin (50 mg/kg) dissolved in 0.1 M citrate buffer (pH 4.5) through intramuscular injection was used for the induction of diabetes which was confirmed by the presence of high blood glucose after 72 hours. Red palm oil or rooibos extract alone did not have any effect on the control of blood glucose in the diabetic rats. The dietary intake of the combined treatment with red palm and rooibos had more health promoting effects on the diabetic rats which included a decrease in blood glucose, glycosylated haemoglobin, fructosamine and increased insulin levels. There was a marked increase in liver glycogen levels in all the diabetic groups. Treatment with rooibos alone showed a decrease in glycogen levels in the diabetic rats. The presence of liver enzymes in the serum, commonly used as indicators of liver damage was increased in all the diabetic rats. However, the combined treatment of diabetic rats with red palm oil and rooibos protected the liver from injury. Red palm oil improved high density lipoprotein cholesterol levels (HDL-cholesterol) in the diabetic rats. There was no effect on the activity of glucokinase, the first enzyme in the the glycolytic pathway in both the untreated and treated diabetic rats. However, the activity of pyruvate kinase, the last enzyme in the glycolytic pathway was reduced in all the diabetic groups. The combined treatment with both red palm and rooibos increased the activity of pyruvate kinase. Oxidative stress was confirmed in the diabetic rats with an increase in the plasma thiobarbituric acid reactive substances (TBARS), an indicator of lipid peroxidation. Treatment of diabetic rats with rooibos and the combination of red palm oil and rooibos brought plasma TBARS to a level that was not significantly different from the normal control group. There was a non-significant reduction of total glutathione in the non-treated and treated diabetic groups. A non-significant increase in the activity of liver catalase was observed in all the treated diabetic groups. The activity of superoxide dismutase was significantly decreased in the liver of diabetic rats. Diabetic rats treated with red palm oil, rooibos and the combined treatment showed an increased activity of superoxide dismutase in the liver. Red palm oil and the combined treatment increased the activity of glutathione peroxidase in both the red blood cells and liver of diabetic rats. Red palm oil, rooibos and their combined treatments also improved the plasma antioxidant capacity such as ferric reducing antioxidant power (FRAP) and oxygen reducing absorbance capacity (ORAC) in the diabetic rats. In conclusion, oxidative stress is actively involved in the progression of diabetes mellitus. Red palm oil and rooibos, most especially their combined treatment showed significant beneficial health promoting effects in the diabetic rats. The remarkable effects of the combined treatment of red palm oil and rooibos in the diabetic rats could be due to their antioxidant profiles. Based on the findings from this study, it can be adduced that these plant products could help in the management of diabetes and its complications and therefore, suggested the need for further research studies on antioxidant therapy in the management of diabetes mellitus.

Diabetes mellitus (DM) and hyperglycemia contribute to sympathetic nervous system (SNS) activation and cardiovascular dysfunction. SNS activation and increased norepinephrine levels downregulate cardiac β-adrenergic receptors (β-AR). The ADMIRE-HF trial identified reduced cardiac SNS innervation as an independent prognostic marker in heart failure. The β-AR antagonist [3H]-CGP12177 was used to quantify cardiac β-AR in ex vivo biodistribution studies in streptozotocin (STZ)-treated rats after 8 weeks of sustained hyperglycemia, and in the Zucker Diabetic Fatty (ZDF) rat model of type-2 diabetes at the onset of hyperglycemia (10 weeks of age) and after a sustained period of hyperglycemia (16 weeks of age). In some STZ rats, insulin was provided at the onset of hyperglycemia, or after a sustained period of hyperglycemia. Insulin treatment at both time points prevented reduced [3H]-CGP12177 binding (33-38% compared to controls) observed in STZ hyperglycemics. ZDF β-ARs were intact at 10 weeks but became reduced (16-25% relative to the Zucker leans) following 6 weeks of hyperglycemia. This work supports that cardiac β-AR are reduced in models of DM and that restoring insulin signalling to maintain glycemic control can normalize β-AR density whether provided early or after a period of sustained hyperglycemia.

Severas altera¸c~oes no metabolismo energ´etico, no consumo de glicose e na sinaliza¸c~ao de insulina cerebral est~ao presentes na doen¸ca de Alzheimer (DA). O modelo animal da DA obtido pela administra¸c~ao intracerebroventricular de estreptozotocina (STZ-icv) em ratos induz um estado de resist^encia `a insulina no c´erebro associado `a disfun¸c~oes colin´ergicas e a d´eficits cognitivos, tornando-o um dos poucos modelos experimentais da forma espor´adica da DA. Este trabalho tem como objetivo caracterizar, neste modelo, as disfun¸c~oes sin´apticas na via hipocampo - c´ortex pr´e-frontal medial (CA1-CPFm) e testar se o tratamento com nicotina ´e capaz de prevenir as disfun¸c~oes sin´apticas e reverter os preju´?zos cognitivos induzido pelo STZ-icv. Para isso, ratos Wistar receberam STZ e foram submetidos a 20 dias de tratamento com nicotina. Dois dias depois, foram realizados nos animais teste de campo aberto e de reconhecimento de objeto. Em seguida os animais foram anestesiados com uretana para que os registros eletrofisiol´ogicos fossem realizados. Um eletrodo foi utilizado para estimular CA1 com pulso pareado e potenciais de campo p´os-sin´apticos (fPSP1) e sua facilita¸c~ao (fPSP2) foram registradas por um eletrodo no CPFm. Ap´os 30 minutos de linha de base, uma estimula¸c~ao em alta frequ^encia foi aplicada para induzir a potencia¸c~ao de longa dura¸c~ao (LTP), seguido de mais quatro horas de registro. Outro grupo experimental foi realizado para avaliar o efeito de longo prazo da STZ-icv e do tratamento com nicotina. Neste grupo, testes comportamentais e eletrofisiol´ogicos foram realizados 60 dias ap´os o fim do tratamento. Independentemente do tempo, os resultados indicam que a STZ produziu uma redu¸c~ao na indu¸c~ao e na manuten¸c~ao da LTP, mas a facilita¸c~ao por pulso pareado (PPF = fPSP2 / fPSP1) mostra que a STZ prejudica a plasticidade pr´e-sin´aptica apenas a curto prazo. O tratamento com nicotina atenua a disfun¸c~ao na LTP induzida pela STZ. Al´em disso, apenas o tratamento de nicotina tamb´em ´e capaz de reduzir a plasticidade pr´e-sin´aptica no grupo controle dois dias ap´os o fim do tratamento. Estes resultados tamb´em est~ao associados com os dados comportamentais, uma vez que a nicotina reverteu os d´eficits de mem´oria de reconhecimento nos animais STZ mas manteve o comportamento explorat´orio reduzido. Sugerimos com isso que o sistema colin´ergico, que desempenha um papel importante em fun¸c~oes cognitivas e na LTP, est´a afetado nos animais injetados com STZ e o tratamento cr^onico com nicotina consegue reduzir os danos na plasticidade sin´aptica e comportamentais, induzidos pela STZ.
Severe abnormalities in brain glucose/energy metabolism and insulin signaling have been documented to play an important role in early stage of alzheimer disease (AD) pathology. Intracerebroventricular administration (icv) of streptozotocin (STZ) in rats can induce an insulin-resistant brain state associated with cholinergic dysfunctions and memory impairments, which make it a suitable experimental model of the sporadic form of AD. The present work aimed to extend the characterization of this model by probing synaptic plasticity dysfunctions in the medial prefrontal cortex (mPFC)- hippocampal (CA1) pathway and test if nicotine can prevent synaptic dysfunction and revert cognitive impairment induced by icv STZ. Here, Wistar rats received bilateral microinjection of STZ and were submitted to 20 days of nicotine treatment. After 2 days of withdrawing the subjects were submitted to open field and object recognition tests. After that, animals were anesthetized with urethane for electrophysiological tests. A twisted bipolar electrode was used to stimulate posterior-dorsal hippocampus (CA1/subiculum) with paired-pulse. Basal field post-synaptic potentials (fPSP1) and facilitated responses (fPSP2) were recorded by a monopolar electrode in the medial mPFC. After 30min of baseline, high frequency stimulation was applied to induce long-term potentiation (LTP) and additional four hours of electrophysiological recordings was performed. Another experimental group was performed to evaluate the long term effect of both icv STZ and nicotine treatment. In this group behavioral and electrophysiological tests were performed with 60 days after chronic treatment. Independently of time, our results indicate that STZ produced a significant decrease in the induction and maintenance of LTP, but paired pulse facilitation (PPF = fPSP2/fPSP1) shows that only the short-term pre-synaptic plasticity was impaired after STZ injection. The nicotine treatment attenuates the STZ-induced LTP dysfunction in the CA1-mPFC pathway. However, just the nicotine treatment (in control group) can reduce pre-synaptic plasticity two days after chronic treatment. These results are also associated with behavioral data, since nicotine treatment reversed the deficits in recognition memory of STZ animals but maintained the reduced exploratory behavior. We suggest that the brain cholinergic system, which plays a role in cognition function and LTP, is affected in STZ injected animals and chronic treatment with nicotine can attenuate the STZ-induced synaptic plasticity and behavioral dysfunctions.

Background: Streptozotocin (STZ) induced diabetes leads to various complications including cardiomyopathy. Recent data suggests transplanted bone marrow stem cells improve cardiac function in diabetic cardiomyopathy. However, whether modified ES, iPS cells, or factors released from these cells can inhibit apoptosis and fibrosis remains completely unknown. The present study was designed to determine the effects of transplanted ES cells overexpressing pancreatic transcription factor 1 a (Ptf1a), a pro-pancreatic endodermal transcription factor, iPS cells, or their respective conditioned media (CM) on diabetic cardiomyopathy. Methods: Experimental diabetes was induced in male Sprague Dawley rats (8-10 weeks old) by intraperitoneal STZ injections (65 mg/kg body weight for 2 consecutive days). Animals were divided into six experimental groups including control, treated with sodium citrate buffer IP, STZ, STZ + ES-Ptf1a cells, STZ + iPS cells, STZ + ES-Ptf1a CM and STZ + iPS CM. Following STZ injections, appropriate cells (1 X 106/mL/injection/day) or CM (2 mL injection/day) were given intravenously for 3 consecutive days. Animals were sacrificed and hearts were harvested at day 28. Histology, TUNEL staining, and Caspase-3 activity were used to assess apoptosis and fibrosis. ERK1/2 phosphorylation was quantified using ELISAs. M-mode echocardiography fractional shortening was used to assess cardiac function. Results: Animals transplanted with ES cells, iPS cells, or both CMs showed a significant (pless than]0.05) reduction in interstitial fibrosis, and apoptosis compared with STZ group. ERK expression was not significantly different compared with STZ. Echocardiography showed a significant (pless than]0.05) improvement in fractional shortening in cell and media transplanted groups compared with STZ. Conclusions: Our data suggest that ES cells, iPS cells, and/or CMs inhibit apoptosis, reduce fibrosis, and improve cardiac function in STZ-treated diabetic rats.
ID: 029049879; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.)--University of Central Florida, 2010.; Includes bibliographical references (p. 33-40).
M.S.
Masters
Burnett School of Biomedical Sciences
Medicine

Thesis (MScMedSc (Biomedical Sciences. Medical Physiology))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: Introduction: Obesity and its associated complications, such as the metabolic syndrome, hypertension and cardiovascular disease, are escalating worldwide. In recognition of this, untested remedies advertised as anti-diabetic agents are flooding the market. Many of these products have limited efficacy, limited tolerability and significant side-effects. One remedy, claiming to have anti-diabetic properties, is DiaviteTM. DiaviteTM, a herbal product, consisting solely of the dried and ground pods of the Prosopis glandulosa tree, which is currently marketed as a food supplement with blood glucose and blood pressure stabilizing properties, as well as having the ability to enhance glucose utilization. It is already freely available from agents as well as sold over the counter at pharmacies. The producers of DiaviteTM are now seeking registration for their product from the Medicines Control Council (MCC) and, therefore, require solid scientific evidence of its effects. Aims: The aims of our study were, on request of the producing company, to determine the efficacy of DiaviteTM (P. glandulosa) as an anti-diabetic agent and possible mechanisms of action of this plant product. Methology: We utilized rat models of streptozotocin (STZ)-induced type 1 diabetes and diet-induced obese (DIO) insulin resistance. Male Wistar rats were rendered (a) type 1 diabetic after a once-off intra-peritoneal injection of STZ at a dose of 40 mg/kg and (b) insulin resistant after being on a high caloric diet (DIO) for 16 weeks. Half the animals of the type 1 diabetes model as well as the insulin resistant model were placed on DiaviteTM treatment (25 mg/kg/day) for a period of 4 – 8 weeks, depending on the model. The STZ-induced type 1 diabetic rats were sacrificed and the pancreata harvested for histological analysis. Animals on the DIO diet were sacrificed and (i) intra-peritoneal fat weight determined (ii) isolated hearts subjected to ischaemia/reperfusion to determine infarct size and protein expression profiles and (iii) cardiomyocytes prepared to determine insulin sensitivity. At the time of sacrifice blood was collected for blood glucose and serum insulin level determination, for both models. In addition, a standard toxicology study was performed in Vervet monkeys over a 3 month period. Results: In our type 1 diabetic model (blood glucose > 10 mmol/L) with a β-cell reserve, DiaviteTM treatment lead to increased serum insulin levels (p < 0.001) in both control and STZ groups as well as increased small β-cell (0 - 2500 μm2) formation (p < 0.001) in the pancreas of the STZ animals. Hearts from DiaviteTM treated control and DIO insulin resistant animals presented with smaller infarct sizes (p < 0.05) after ischaemia/reperfusion compared to their controls. DiaviteTM treatment lead to the increase of basal (p < 0.01) and insulin-stimulated (p < 0.05) glucose uptake in cardiomyocytes prepared from DIO insulin resistant animals. DiaviteTM treatment also led to significantly suppressed PTEN expression and activity (p < 0.01) in the DIO insulin resistant animals. In addition, DiaviteTM treatment had (i) no obvious detrimental effects in our rat models and (ii) no toxicity over a 3 month period in vervet monkeys. Conclusion: Our present study has shown that DiaviteTM treatment lowers fasting blood glucose levels, stimulates insulin secretion and leads to the formation of β-cells. In addition, oral consumption of DiaviteTM elicits cardioprotection against an ischaemic incident. DiaviteTM treatment improves insulin sensitivity of cardiomyocytes. Furthermore, it has been established that DiaviteTM treatment has no obvious detrimental effects in either of our rat models and no short-term toxic effects over a 3 month period in Vervet monkeys (data not shown). We thus conclude that in our models, DiaviteTM proved safe and it seems as if DiaviteTM, after short-term use, is beneficial as a dietary supplement.
AFRIKAANSE OPSOMMING: Inleiding: Vetsug, en die gepaardgaande komplikasies, soos die metaboliese sindroom, hipertensie en kardiovaskulêre siektes, neem wêreldwyd toe. Daar is tans verskeie middels op die mark wat as anti-diabetiese middels geadverteer word. Baie van hierdie geadverteerde produkte het beperkte effektiwiteit en het verskeie newe-effekte. Een so ‘n middel, is DiaviteTM. DiaviteTM is 'n plantproduk, wat slegs uit die gedroogte en fyngemaakte peule van die P. glandulosa boom bestaan. Hierdie produk word tans bemark as 'n voedselaanvulling met beide bloedglukose en bloeddruk stabiliserende eienskappe, asook die vermoë om glukose gebruik te verbeter. DiaviteTM is reeds vrylik beskikbaar van agente sowel as verkrygbaar by verskeie apteke. Die produsente van DiaviteTM wil aansoek doen om registrasie vir hul produk by die Medisynebeheerraad (MCC) en hulle vereis daarom wetenskaplike bewyse van die gevolge van die gebruik van hierdie produk. Doel: Die doel van ons studie was om op versoek van die produksie maatskappy, die doeltreffendheid van DiaviteTM (P. glandulosa) as 'n anti-diabetiese behandeling te evalueer, sowel as die moontlike meganismes van werking van hierdie plantproduk. Metodes: Ons het gebruik gemaak van rot modelle van (i) streptozotocin (STZ)-geïnduseerde tipe 1 diabetes en (ii) dieet-geïnduseerde vetsugtig (DIO) insulienweerstandigheid. Manlike Wistar rotte was as (a) tipe 1 diabeties geklassifiseer na 'n eenmalige, intra-peritoneale inspuiting van STZ teen 'n dosis van 40 mg/kg en as (b) insulienweerstandig geklassifiseer, nadat hulle op 'n hoë kalorie dieet (DIO) vir 16 weke was. Die helfte van beide die tipe 1 diabetes en die insulienweerstandige groep diere was met DiaviteTM behandel (25 mg/kg/dag) vir 'n tydperk van 4 - 8 weke, afhangende van die model. Die STZ-geïnduseerde tipe 1 diabetes rotte is geslag en die pankreata geoes vir histologiese analise. Diere op die DIO dieet is geslag en (i) die intra-peritoneale vet gewig bepaal, (ii) die geïsoleerde harte blootgestel aan isgemie/herperfusie om die infarkt groottes vas te stel, sowel as die proteïenuitdrukkingsprofiele te bepaal en (iii) kardiomiosiete was berei om die insulien sensitiwiteit te bepaal. Ten tyde van die slagting is bloedmonsters geneem vir bloedglukose en serum insulien vlak bepaling, vir beide modelle. Additioneel, is 'n standaard toksologie studie met Vervet apies oor 'n 3 maande tydperk uitgevoer. Resultate: In die model van tipe 1 diabetes (bloed glukose > 10 mmol/L), met 'n β-sel reserwe, is gevind dat DiaviteTM behandeling tot verhoogde serum insulien vlakke (p < 0.001) in beide kontrole en STZ groepe lei. DiaviteTM behandeling lei ook tot ‘n hoër vlak van klein β-sel (0 - 2500 μm2) vorming (p < 0.001) in die pankreas van die STZ diere. Die harte van die DiaviteTM behandele kontrole en DIO groep het kleiner infarkt groottes (p < 0.05) getoon na isgemie/herperfusie in vergelyking met hul kontrole groepe. DiaviteTM behandeling het ook gelei tot verhoogde basal (p < 0. 01) en insulin-gestimuleerde (p < 0. 05) glukose opname in kardiomiosiete wat berei was van DIO insulinweerstandige diere. DiaviteTM behandeling het PTEN uitdrukking en aktiwiteit aansienlik onderdruk (p < 0.01) in die DIO insulienweerstandige groep diere. Daar is dus gevind dat DiaviteTM behandeling (i) geen duidelike nadelige invloed in ons rot-modelle en (ii) geen toksisiteit oor 'n 3 maande tydperk in Vervet apies getoon nie. Gevolgtrekking: Ons huidige studie toon dus dat DiaviteTM behandeling vastende bloedglukosevlakke verlaag, insulien sekresie stimuleer en die proses van β-sell vorming bevorder. Additioneel, is gewys dat wanneer DiaviteTM mondelings gebruik word, dit die hart beskerm teen isgemiese insidente. Ons het ook getoon dat DiaviteTM behandeling insuliensensitiwiteit van kardiomiosiete verhoog. Verder is daar vasgestel dat DiaviteTM behandeling geen ooglopende nadelige gevolge in beide ons rot-modelle getoon het nie en daar geen korttermyn-toksiese effekte oor 'n 3 maande tydperk in Vervet apies (data nie getoon) is nie. Ons kan dus aflei dat Diavite TM in ons modelle veilig is en na kort termyn gebruik, voordelig is as 'n dieetaanvulling.

Indiana University-Purdue University Indianapolis (IUPUI)
Bone disease and degradation is a ubiquitous problem, the complexity and treatment of which humanity has only begun to understand. Diabetes Mellitus is a disease which, in all forms, profoundly effects the organs of the body, bone included. As is often the case in biology, there are inherent differences between the sexes when considering skeletal development and disease progression and outcome. Although there are several reported mouse models for diabetes, until now there has been no characterization of bone disease in any model where diabetes occurs with equal frequency in males and females in greater than 90% of animals. In this study, a protocol for reliable induction of diabetes in both sexes using intraperitoneal injections of Streptozotocin was developed. The resulting bone phenotype in male and female mice was characterized and compared to weight and age matched control groups. In this model female diabetic mice exhibited a robust deficit in bone quality, while both sexes experienced loss of beta-cell mass and increased glycation of hemoglobin rendering the diabetic mice unable to produce insulin endogenously. Further, these mice were unable to metabolize exogenous insulin injected during insulin tolerance testing. This model is a strong candidate for future exploration of osteoporotic bone disease, Diabetes Mellitus, and the link between estrogen and glucose sensitivity.

The principal objective of this study was to develop an alternative non-genetic rat model for type 2 diabetes (T2D). Six-week-old male Sprague-Dawley rats (190.56 ± 23.60g) were randomly divided into six groups namely: Normal Control (NC), Diabetic/Streptozotocin Control (STZ), Fructose-10 (FR10+STZ), Fructose-20 (FR20+STZ), Fructose-30 (FR30+STZ) and Fructose-40 (FR40+STZ) and were fed a normal rat pellet diet ad libitum for 2 weeks. During this period, the two control groups received normal drinking water whilst the fructose groups received 10, 20, 30 and 40% fructose in drinking water ad libitum respectively. After two weeks of dietary manipulation, all groups except the NC group received a single injection (i.p.) of streptozotocin (STZ) (40mg/kg BW) dissolved in citrate buffer (pH 4.4). The NC group received only a vehicle buffer injection (i.p.). One week after the STZ injection, animals with non-fasting blood glucose >300 mg/dl were considered as diabetic. Three weeks after the STZ injection, the animals in FR20+STZ, FR30+STZ and FR40+STZ were eliminated from the study due to the severity of diabetes and the FR10+STZ group was selected for the remainder of the 11 weeks experimental period. The significantly (p < 0.05) higher fluid intake, blood glucose, serum lipids, liver glycogen, liver function enzymes and insulin resistance (HOMA-IR) and significantly (p < 0.05) lower body weight, oral glucose tolerance, number of pancreatic β-cells and pancreatic β-cell functions (HOMA-beta) of FR10 group demonstrate that the 10% fructose-fed followed by 40 mg/kg of BW STZ injected rat can be an excellent alternative model for T2D. To validate this newly-developed model, an acute intervention trial study was conducted to investigate the anti-diabetic effects of L-Carnitine and white mulberry leaf tea extracts in the newly developed animal model of type 2 diabetes (T2D). Male Sprague-Dawley rats (mean BW 191.88g±16.40g) were randomly divided into 5 groups namely: Normal Control (NC), Diabetic/Streptozotocin control (FR10+STZ), Mulberry Tea Low (FR10+STZ+MTL, 0.25%), Mulberry Tea High (FR10+STZ+MTH, 0.5%), and L-Carnitine (FR10+STZ+CARN). In first three weeks, T2D was induced in all other groups except NC group by using above-mentioned procedure. Mulberry tea was supplied ad libitum and L-carnitine was administered to the FR10+STZ+CARN group at a concentration of 500mg/kg BW once daily during week 4-8 of the intervention trial. The FR10+STZ+CARN group had significantly (p < 0.05) lower total cholesterol, triglycerides, total proteins and fluid intake compared to the diabetic control (FR10+STZ). The NFBG non-significantly reduced in FR10+STZ+CARN group compared to the FR10+STZ group, whereas MT did not. FR10+STZ+MTL had significantly higher serum triglycerides level compared to the NC group, and significantly higher HDL-cholesterol and fluid intake compared to the FR10+STZ group. FR10+STZ+CARN and FR10+STZ+MT groups had significantly lower total proteins compared to NC and FR10+STZ groups, but significantly lower albumin compared to NC group only. The data of the this section of the study suggest that CARN may be effective in normalizing lipid profiles rather than blood glucose in diabetic rats which may aid in the reversal of insulin resistance. On the other hand, MT used in this study did not display any significantly beneficial anti-diabetic effects at least in this experimental condition.
Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2011.

碩士
臺灣大學
臨床醫學研究所
98
1.Background: Among working adults in developed countries, diabetic retinopathy (DR) remains the leading cause of blindness and visual impairment. New evidence indicates that DR shares similarities with chronic inflammatory disease, and inflammation may play a central role in the development of DR. In diabetes, leukocytes become less deformable and retinal leukostasis increases, corresponding to the fact that the expression of cellular adhesion molecules such as intercellular adhesion molecule-1 (ICAM-1) are increased in retinal vasculature, which affects retinal endothe¬lial function, retinal perfusion, angiogen¬esis and vascular permeability. The inflamed retina tissues release increased levels of adhesion molecules, cytokines and chemokines for leukocyte recruitment. The concentrations of inflammatory mediators such as monocyte chemoattractant protein-1 (MCP-1) and fracktalkine (FKN) are reported to be increased in the vitreous of patients with proliferative diabetic retinopathy. It has been suggested that increased oxidative stress, which generates excess reactive oxygen species (ROS), is a key point in the pathogenesis of DR. The use of appropriate antioxidants may have potential to inhibit the inflammatory changes in the development of DR in animals, including activation of NF-κB, leukostasis, and formation of ROS with the ability of scavenging free radicals, or increasing the antioxidants defense enzyme capabilities. Cilostazol, is a phosphodiesterase 3 (PDE3) inhibitor which results in inhibition of platelet aggregation and vasodilation leading to reduction in arterial pressure. Among recent studies, potent anti-inflammatory and anti-oxidative effects of cilostazol were shown through the suppression of cytokines, adhesion molecules, and other inflammatory mediators leading to leukocyte-endothelial cell interactions and platelet-mediated tissue damage after transient retina ischemia. Besides, it has been reported that cilostazol could reduce inflammatory burden and oxidative stress in hypertensive type 2 diabetes mellitus patients. We hypothesized that cilostazol inhibits the expression of various inflammatory mediators and adhesion molecules such as MCP-1, FKN and ICAM-1 by blocking NF-κB activation in the development of DR. Treatment with cilostazol could also increase the activity of antioxidants defense enzymes and reduce levels of oxidatively modified DNA (8-hydroxy-2''-deoxyguanosine), oxidatively protein (nitrotyrosine) and oxidative lipids (acrolein) in the diabetic retina. We will assess retinal expression of these inflammatory mediators and oxidative stress biomarkers in streptozotocin (STZ) induced diabetic rat model and set up cilostazol treatment model to define the possible anti-inflammatory and anti-oxidative effect of cilostazol in DR. 2.Material and methods: Thirty 6 weeks old female Wistar rats with the body weight about 200-250g were divided into a normal control group (n=10) and a STZ-induce diabetic group (n=20). Twenty rats were intraperitoneally injected with STZ to induce diabetes. Eight weeks later, the eyeball of each rat was taken out to obtain fresh retina tissues. We performed polymerase chain reaction (PCR), western blot analysis, hematoxylin and Eosin (H&E) and immunohistochemical staining to assess ICAM-1, MCP-1 and FKN in the retina of rats. The concentrations of ICAM-1, MCP-1 and FKN in the aqueous humor and vitreous cavity were examined by enzyme-linked immunosorbent assay (ELISA). The nuclear factor (NF)-κB activity was assessed by IHC and electrophoresis mobility shift assay (EMSA). Besides, the contents of 8-OHdG, nitrotyrosine and acrolein in the retina were measured by IHC in order to evaluate the change of oxidative stress in the diabetic retina. 3.Results and discussions: The administration of cilostazol for eight weeks in diabetic rats did not alter the blood glucose levels compared with untreated diabetic rats. Cilostazol inhibits the increase of ICAM-1, MCP-1 and FKN mRNA and protein expression in the retina, as well as the increase of ICAM-1, MCP-1 and FKN contents in the aqueous humor and vitreous cavity. Consistent with these findings, cilostazol attenuated the enhanced activation of NF-κB in diabetic rats by IHC and EMSA findings. The levels of oxidatively modified DNA (8-OHdG), nitrotyrosine and oxidative lipids (acrolein) were also diminished in the cilostazol-treated diabetic group. 4.Conclusions: Cilostazol reduces inflammatory reactions and oxidative stress in the development of DR. The anti-inflammatory effects of cilostazol is supposed to be mediated by the inhibition of NF-κB activity, and the subsequent decrease in inflammatory mediators such as ICAM-1, MCP-1 and FKN expression in the retina. The effects of cilostazol had been widely studied in the treatment of diabetic vasculopathy, neuropathy, nephropathy and retinopathy of the animal model. In the future, cilostazol may be clinically applied in the treatment of diabetic patients to avoid progressive visual loss.

碩士
國立臺灣大學
臨床醫學研究所
99
1.Background Diabetic retinopathy, a sight-threatening complication of diabetes, is the major cause of blindness in young adults. Studies have documented that sustained hyperglycemia is the instigating cause of disrupted normal cellular metabolism leading to the development of retinopathy. Diabetes increases oxidative stress, and increased oxidative stress is one of the key regulators in the development of diabetic complications. Oxidative stress results from an imbalance between oxidant production, including reactive oxygen species (ROS), reactive nitrogen species (RNS), and antioxidant defense mechanisms.The outer retina is avaseular and receives its oxygen supply from the choroid,which lacks hyperoxia-induced autoregulation. Therefore, photoreceptors are exposed to higher level of tissue oxygen than most other tissue. This phenomenon renders retina more susceptible to oxidative stress.Consequences of chronic oxidative stress include damage to biological macromolecules such as DNA, lipids, proteins, and carbohydrates. An association between oxidative stress and the development of diabetes complications has been recognized for over 20 years.Increased production of reactive oxygen species has been strongly implicated in the pathogenesis of diabetic retinopathy. Besides, inflammation may also play a central role in the development and progression of diabetic retinopathy. Astaxanthin (AST), a dietary carotenoid, is often decreasing the formation of products of oxidative damage induced by biological molecules.Astaxanthin is a powerful biological antioxidant occurring naturally in a wide variety of living organisms, and is present in many well-known sea foods such as salmon, trout, red sea-bream, shrimp, lobster and fish eggs. Recent studies have shown that astaxanthin is a powerful biological antioxidant. Due to potent anti-oxidative and anti-inflammatory effects of AST, we hypothesize that AST could reduce the oxidative mediators and increase antioxidant enzyme defense system. Beside, AST may also reduce inflammatory mediators. 2.Purpose This study is to evaluate the potential protective effects of AST against retinal oxidative damage in streptozotocin(STZ) - induced diabetic rats. 3.Material and Methods Fifty 6 weeks old female Wistar rats with the body weight about 200-250g were divided into a healthy control group(n=10) and a STZ- induced diabetic group(n=40). These forty rats received intra- peritoneal injection with STZ to induce diabetes and randomly divided into four groups. A group of rats received normal powdered diet or powdered diet supplemented with 0.6 or 3mg/kg AST or 0.5mg/kg lutein. Eight weeks later, the eyeball of each rat was taken out to obtain fresh retina tissues. We performed immunohistochemistry (IHC), western blot analysis, enzyme-linked immunosorbent assay (ELISA),reverse transcription - polymerase chain reaction (RT-PCR), and electrophoretic mobility shift assays (EMSA) to assess oxidative stress and inflammatory mediators in diabetic retinopathy. 4.Results and discussions AST could reduce the oxidative mediators (8-hydroxy-2''- deoxyguanosine (8-OHdG), Nitrotyrosine ,and acrolein ) and increase antioxidant enzyme defense system(heme oxygenase, peroxiredoxin, and thioredoxin ). AST also reduce inflammatory mediators (intercellular adhesion molecule (ICAM-1), monocyte chemoattractant protein-1 (MCP-1), and fractalkine (FKN)) and the activity of transcription factor NF-κB. 5.Conclusions Astaxanthin could reduce oxidative stress and inflammatory reactions in diabetic retina rat model .The antioxidant and anti-inflammatory effect of Astaxanthin was supposed to be mediated by inhibition of NF-κB activity and reduced the downstream products. Astaxanthin acted as antioxidants by facilitating the activity of antioxidant enzymes to inhibit oxidative stress and reduced the damage to biological macromolecules such as DNA, lipids and proteins. Axtaxanthin seems to be the nutritional supplement for prevention of diabetic retinopathy progression.

The aim of the present study was to develop an alternative non-obese non-genetic rat model of type 2 diabetes (T2D). Six-week-old male Sprague-Dawley rats were randomly divided into six groups, namely: Normal Control (NC), Diabetic Control (DBC), Caffeine 5 mg/kg BW + STZ (CAF5), Caffeine 10 mg/kg BW + STZ (CAF10), Caffeine 20 mg/kg BW + STZ (CAF20) and Caffeine 40 mg/kg BW + STZ (CAF40) and were fed a commercially available rat pellet diet and normal drinking water ad libitum throughout the 13 weeks experimental period. After a one week acclimatization period, diabetes was induced in the animals in DBC and all CAF groups with an injection (i.p.) of the respective dosages of caffeine (mg/kg BW) 15 min before the injection (i.p.) of STZ (65 mg/kg BW) when normal saline was injected to the DBC group instead of caffeine. The NC group received normal saline and citrate buffer instead of caffeine and STZ, respectively. One week after the STZ injection, animals with non-fasting blood glucose > 300 mg/dl were considered as diabetic. Three weeks after the STZ injection, the animals in the CAF5 and CAF10 groups were eliminated from the study due to the severity of diabetes and the experiment was continued with the remainder groups for a 13 weeks period. At the end of the experimental period the rats were euthanized and blood and organ samples were collected for subsequent analysis. The data of daily food and fluid intake, weekly body weight and blood glucose, oral glucose tolerance test, serum insulin, fructosamine, lipid profile, organ specific and antioxidative enzymes, anti-diabetic drug response tests, and liver, heart, kidney and pancreas histopathology suggest that the CAF20 group can be a new and alternative non-obese non-genetic chemically-induced model for T2D and can be therefore used for both chronic and acute research studies as well as pharmacological screening of new anti-diabetic drugs.
Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2013.

Animal models of Alzheimer's disease display cognitive insufficiencies which mimic human symptoms and occur at a given age or post-treatment time. Animals are typically tested using canonical behavioral tests, lasting minutes and taking place mostly in the non-active period of the daily cycle. Animals are exposed to certain amounts of manipulation-induced stress. Our work represents a validation study for the rat behavioral system IntelliCage. The tested individuals live freely in a group and their behavior is monitored continuously. It is however possible to set up individual tests for each animal or a group of animals. The rats are not subject to human manipulation and hence the results are not affected by manipulation-induced stress. We tested early cognitive impairment in the transgenic rat model TgF344-AD at 6 - 8 months of age. Further, we tested two most common protocols of the streptozotocin model, i.e. single dose of intracerebroventricular 3 mg/kg streptozotocin and double dose 48 hrs apart. Results were compared with the canonical Morris Water Maze (MWM) test. In the MWM test, transgenic animals did not differ from controls in any of the studied parameters. The streptozotocin model displayed a deficit only in the double dose group. However in the IntelliCage, transgenic animals displayed...

碩士
國立臺灣大學
生理學研究所
93
A new experimental type 2 diabetic syndrome, which is closer to human non-insulin-dependent diabetes mellitus, has been reported in adult rats administered streptozotocin (STZ) and partially protected with a suitable dose of nicotinamide (NA). The accelerated formation of advanced glycation end products (AGEs) on long-lived connective tissue may account for some of the complications of diabetes such as stiffing of collagen, vascular narrowing, and arterial stiffing. In this study, we determined the effects of long-term treatment with aminoguanidine (AG), an inhibitor of AGEs formation, on hemodynamic parameters describing arterial wall elasticity and pulse wave reflection in STZ-NA diabetic rats. Rats at 2 months were given NA 180mg/Kg i.p., 30 mins before an intravenous injection of 50mg/Kg STZ . This STZ-NA rats before use, and compared with the untreated age-matched controls. Mean while, the STZ-NA diabetic rats were treated for 4 (STZ-NA4) and 8 weeks (STZ-NA8) with AG (daily peritoneal injections of 50 mg/kg) and compared with the untreated diabetic groups. At 180 mg/Kg, NA largely prevented STZ-induced body weight loss, hyperglycemia, and hypoinsulinemia in the rats with diabetes. In comparison with controls, the STZ-NA rats of 8 weeks but not 4 weeks after induction of diabetes showed a decrease in cardiac output in the absence of any significant changes in mean aortic pressure, having increased total peripheral resistance (Rp), at 54.9±2.5 versus 65.8±2.8mmHg•s•ml-1 (P＜0.05).The STZ-NA8 diabetes also contributed to an increase in aortic characteristic impedance (Zc), from 1.489±0.105 to 1.952±0.091 mmHg．s．ml-1 (P＜0.05) and a decrease in wave transit time (τ), from 25.8±1.2 to 20.6±0.91 ms (P＜0.05). The elevated Zc and the reduced τ suggest that STZ-NA8 diabetic rats may have a detrimental effect on aortic distensibility. Meanwhile, the heavy reflection intensity occurred in rats with STZ-NA of 8 weeks diabetes because of the diminished τ and the increased wave reflection factor (Rf) (0.49±0.03 versus 0.61±0.04, P＜0.05). After exposure to AG, the STZ-NA8 diabetic rats exhibited a significant improvement in physical properties of the resistance vessels, as evidenced by the reduction of 18.1﹪in Rp. Meanwhile, AG retarded the diabetes-induced decline in aortic distensibility, as reflected in the decrease of 18.7﹪ in Zc (P＜0.05) and the increase of 21.8﹪inτ(P＜0.05). AG also prevented the diabetes-induced augmentation in systolic loading condition for the left ventricle coupled to the arterial system, due to the increased τand the decreased Rf (-22.9﹪). Moreover, the ratio of LV weight to body weight was lowered by AG treatment, suggesting that the prevention of the diabetes-related cardiac hypertrophy may correspond to the drug-induced decline in LV systolic load. By contrast, AG exerted no effects on the mechanical properties of Winkessel vessels, as well as resistance vessels, in normal controls and STZ-NA of 4 weeks diabetes. We conclude that only rats with STZ-NA of 8 weeks diabetes produce a detrimental effect on the pulsatile nature of blood flows in arteries. Treatment with AG may impart significant protection against aortic stiffening in STZ-NA of 8 weeks diabetic rats possibly through inhibition of the AGEs-accumulation on collagen in the arterial wall.

Vaskuläre Komplikationen wie Atherosklerose sind bei Diabetikern weit verbreitet. Eine erhöhte Produktion reaktiver Sauerstoffspezies trägt zu einer Dysfunktion des Endothels bei Diabetes und hohen Glukosespiegeln bei. Glutathion (GSH) ist das häufigste zelluläre Thiol und stellt ein bedeutendens Antioxidans des menschlichen Organismus dar. Das Multidrug Resistance Protein 1 (MRP 1) ist im Endothel der Haupttransporter von oxidiertem GSH. Blockiert man MRP 1, so wird unter oxidativem Stress der intrazelluläre GSH-Spiegel erhalten. In dieser Arbeit wird der Einfluss von MRP 1 auf die endotheliale Funktion und Produktion reaktiver Sauerstoffspezies bei Diabetes und erhöhten Glukosespiegeln anhand von MRP 1-/- -Mäusen und Wildtyp-FVB-Tieren untersucht. Acht Wochen nach Injektion von STZ wurde die endothelabhängige Vasorelaxation an den isolierten thorakalen Aorten bestimmt. Diabetische Wildtyp-Tiere wiesen eine signifikant verminderte endothelabhängige Vasorelaxation auf. In MRP 1-/- -Tieren hingegen kam es zu keiner Beeinträchtigung der Endothelfunktion. Die endothelunabhängige Vasorelaxation war nicht signifikant unterschiedlich. STZ-induzierter Diabetes führte zu einer signifikant erhöhten Produktion von Superoxidanionen sowie Wasserstoffperoxid in Wildtyp-Tieren. Diabetische MRP 1-/- -Mäuse hingegen zeigten keinen Anstieg der Produktion reaktiver Sauerstoffspezies. Erhöhte Glukosekonzentrationen führten in vitro in humanen aortalen Endothelzellen ebenso zur erhöhten Superoxidanion-Produktion. In Zellen, in denen MRP 1 mittels siRNA herunterreguliert war, zeigte sich keine Erhöhung von Superoxidanionen. In Wildtyp-Mäusen führte Diabetes zu einer Verminderung des vaskulären GSH-Spiegels, wohingegen bei MRP 1-/- -Tieren keine Veränderung auftrat. Diese Daten weisen auf die wichtige Rolle von MRP 1 bei der unter hohen Glukosekonzentrationen auftretenden endothelialen Dysfunktion hin. MRP 1 stellt somit einen neuen Ansatzpunkt in der Behandlung der durch Diabetes ausgelösten vaskulären Dysfunktion dar
Vascular complications and atherosclerosis are common in patients with diabetes. An increased production of reactive oxygen species contributes to endothelial dysfunction in diabetes. A major cellular defense against reactive oxygen species is Glutathione. The multidrug resistance associated protein 1 is the main transporter of oxidized glutathione in endothelial cells. Blockade of MRP 1 prevents endothelial cell dysfunction induced by reactive oxygen species. Diabetes was induced in 12 week old male MRP 1-/- mice or corresponding FVB background wildtype mice by injection of streptozotocin. Eight weeks thereafter endothelium-dependent vasorelaxation was blunted in isolated thoracic aortae. In aortae from diabetic mice lacking MRP 1, endothelium-dependent vasorelaxation was only mildly impaired. STZ induced diabetes increased aortic superoxide and hydrogen peroxide production in wildtype animals, while in aortae from MRP 1-/- mice the reactive oxygen species production was nearly unchanged by diabetic conditions. Aortic levels of reduced glutathione were diminished in diabetic FVB. Glutathione levels did not change in diabetic MRP 1-/- mice. These data indicate that MRP 1 plays an important role for endothelial dysfunction and reactive oxygen species production in diabetes and under conditions of high glucose. MRP 1 therefore may represent a therapeutic target in treatment of diabetes induced vascular dysfunction

According to the World Health Organization (WHO), 15% of couples in reproductive age suffer from infertility problems, and up to 60% of cases are caused by male factor. Causes of this condition could be genetic background, environmental factors and various diseases, including diabetes mellitus (DM). The aim of this study was to investigate the effects of DM on reproductive parameters and expression of selected testicular genes using mouse model (FVB inbred mouse strain). DM (type 1) was artificially induced by chemical substance streptozotocin, which causes destruction of pancreatic β cells. These mice were exposed to diabetic condition for 6 weeks and then subjected to analysis. Our results have shown that diabetic condition had an impact on body weight, weight of reproductive organs as well as kidneys and livers. We also observed decreased concentration and viability of diabetic sperm compared to control. Moreover, we noticed increased staining with apoptotic marker annexin V. Further, we evaluated changes of sperm nuclear proteins - protamines. In diabetic animals, we observed higher number of sperm with insufficient protamination. Nevertheless, protamine 1 to protamine 2 ratio (P1/P2), a marker of male fertility, was not altered in sperm of diabetic animals compared to control. Regarding the...

博士
中國醫藥大學
中醫學系博士班
99
Animal studies have shown that electroacupuncture (EA) at Zusanli (ST-36) and Zhongwan (CV-12) acupoints reduces plasma glucose concentrations in rats with type II diabetes. However, whether EA reduces plasma glucose levels in type I diabetes is still unknown. In this study, we explore the various non-insulin-dependent pathways involved in EA-induced lowering of plasma glucose. Streptozotocin (STZ) (60 mg kg-1, i.v.) was administered via the femoral vein to induce insulin-dependent diabetes in non-adrenalectomized and in adrenalectomomized rats. EA (15Hz) was applied for 30min to bilateral ST-36 acupoints after administration of Atropine (0.1 mg kg-1 i.p.), Eserine (0.01mg kg−1 i.p.), or Hemicholinium-3 (5 μg kg-1 i.p.) in nonadrenalectomized rats. Rats administered acetylcholine (0.01mg kg-1 i.v.) did not undergo EA. Adrenalectomized rats underwent EA at bilateral ST-36 acupoints without further treatment. Blood samples were drawn from all rats before and after EA to measure changes in plasma glucose levels. Expression of insulin signaling proteins (IRS1, AKT2) in atropine-exposed rats before and after EA was measured by western blot. Atropine and hemicholinium-3 completely blocked the plasma glucose lowering effects of EA, whereas eserine led to a significant hypoglycemic response. In addition, plasma glucose levels after administration of acetylcholine were significantly lower than the fasting glucose levels. In STZ-adrenalectomized rats, EA did not induce a hypoglycemic response. EA stimulated the expression of IRS1 and AKT2 and atropine treatment blocked the EA-induced expression of those insulin signaling proteins. Taken together, EA at the ST-36 acupoint reduces plasma glucose concentrations by stimulating the cholinergic nerves.