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Relevant bibliographies by topics / Arachidonic acid

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Academic literature on the topic 'Arachidonic acid'

Author: Grafiati

Published: 4 June 2021

Last updated: 8 June 2024

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Journal articles on the topic "Arachidonic acid"

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Pickford, L. B., A. J. Polverino, and G. J. Barritt. "Evidence from studies employing radioactively labelled fatty acids that the stimulation of flux through the diacylglycerol pool is an early action of vasopressin on hepatocytes." Biochemical Journal 245, no. 1 (July 1, 1987): 211–16. http://dx.doi.org/10.1042/bj2450211.

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1. In isolated hepatocytes prelabelled with [14C]-arachidonic, -stearic, -linoleic, -oleic or -palmitic acids, vasopressin increased the amount of radioactivity present in diacylglycerols. The largest increase was observed in cells labelled with arachidonic or stearic acids. 2. In cells prelabelled with [14C]- or [3H]-arachidonic acid, the onset of the increase in radioactivity in diacylglycerols induced by vasopressin was slow, the increase was partly dependent on the presence of extracellular Ca2+, and was associated with an increase in radioactivity present in phosphatidic acid which was more rapid in onset. Vasopressin decreased the amount of [3H]arachidonyl-phosphatidylinositol 4,5-bisphosphate, but the magnitude of this decrease was less than 10% of the observed increase in radioactivity in [3H]arachidonyl-diacylglycerol. 3. The concentration of vasopressin which gave half-maximal increase in [14C]arachidonyl-diacylglycerol at low extracellular Ca2+ was 10-fold higher than that which gave half-maximal stimulation of 45Ca2+ efflux. Phenylephrine, but not glucagon, also increased the amount of [14C]arachidonyl-diacylglycerol. 4. It is concluded that an early action of vasopressin on the liver cell is to increase the flux of carbon from phospholipids, including the phosphoinositides, to diacylglycerols.

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Patton, G. M., H. Kadowaki, H. Albadawi, H. M. Soler, and M. T. Watkins. "Effect of hypoxia on steady-state arachidonic acid metabolism in bovine aortic endothelial cells." American Journal of Physiology-Heart and Circulatory Physiology 272, no. 3 (March 1, 1997): H1426—H1436. http://dx.doi.org/10.1152/ajpheart.1997.272.3.h1426.

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At the onset of acute hypoxia, eicosanoid synthesis by bovine aortic endothelial cells (BAEC) markedly decreases, reflecting a decreased release of arachidonic acid from endogenous stores. To determine the cause of decreased arachidonic acid release, we pulse-labeled BAEC with [14C]arachidonic acid for 5 min under normoxic conditions and chased cells for 1 h under normoxic or hypoxic conditions. The 14C incorporation and specific activity (disintegrations per minute per nanomole) of three major arachidonyl molecular species (16:0-20:4, 18:1-20:4, and 18:0-20:4) of each phospholipid class were determined in cells chased under either of the two conditions. There was no relevant difference between normoxic and hypoxic cells in the metabolism of any of the arachidonyl molecular species of diacyl lipids. However, there was a marked decrease (approximately 40%) in the turnover of arachidonyl alkenylacyl phosphatidylethanolamine in the hypoxic cells. From these results, it appears that the source of arachidonic acid supporting constitutive eicosanoid synthesis in BAEC is alkenylacyl phosphatidylethanolamine and that the limiting enzyme activity determining the rate of eicosanoid synthesis is a plasmalogen-specific phospholipase A2.

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Kakularam, Kumar R., Miquel Canyelles-Niño, Xin Chen, José M. Lluch, Àngels González-Lafont, and Hartmut Kuhn. "Functional Characterization of Mouse and Human Arachidonic Acid Lipoxygenase 15B (ALOX15B) Orthologs and of Their Mutants Exhibiting Humanized and Murinized Reaction Specificities." International Journal of Molecular Sciences 24, no. 12 (June 12, 2023): 10046. http://dx.doi.org/10.3390/ijms241210046.

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The arachidonic acid lipoxygenase 15B (ALOX15B) orthologs of men and mice form different reaction products when arachidonic acid is used as the substrate. Tyr603Asp+His604Val double mutation in mouse arachidonic acid lipoxygenase 15b humanized the product pattern and an inverse mutagenesis strategy murinized the specificity of the human enzyme. As the mechanistic basis for these functional differences, an inverse substrate binding at the active site of the enzymes has been suggested, but experimental proof for this hypothesis is still pending. Here we expressed wildtype mouse and human arachidonic acid lipoxygenase 15B orthologs as well as their humanized and murinized double mutants as recombinant proteins and analyzed the product patterns of these enzymes with different polyenoic fatty acids. In addition, in silico substrate docking studies and molecular dynamics simulation were performed to explore the mechanistic basis for the distinct reaction specificities of the different enzyme variants. Wildtype human arachidonic acid lipoxygenase 15B converted arachidonic acid and eicosapentaenoic acid to their 15-hydroperoxy derivatives but the Asp602Tyr+Val603His exchange murinized the product pattern. The inverse mutagenesis strategy in mouse arachidonic acid lipoxygenase 15b (Tyr603Asp+His604Val exchange) humanized the product pattern with these substrates, but the situation was different with docosahexaenoic acid. Here, Tyr603Asp+His604Val substitution in mouse arachidonic acid lipoxygenase 15b also humanized the specificity but the inverse mutagenesis (Asp602Tyr+Val603His) did not murinize the human enzyme. With linoleic acid Tyr603Asp+His604Val substitution in mouse arachidonic acid lipoxygenase 15b humanized the product pattern but the inverse mutagenesis in human arachidonic acid lipoxygenase 15B induced racemic product formation. Amino acid exchanges at critical positions of human and mouse arachidonic acid lipoxygenase 15B orthologs humanized/murinized the product pattern with C20 fatty acids, but this was not the case with fatty acid substrates of different chain lengths. Asp602Tyr+Val603His exchange murinized the product pattern of human arachidonic acid lipoxygenase 15B with arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid. An inverse mutagenesis strategy on mouse arachidonic acid lipoxygenase 15b (Tyr603Asp+His604Val exchange) did humanize the reaction products with arachidonic acid and eicosapentaenoic acid, but not with docosahexaenoic acid.

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Sanchez-Olea, R., M. Morales-Mulia, J. Moran, and H. Pasantes-Morales. "Inhibition by polyunsaturated fatty acids of cell volume regulation and osmolyte fluxes in astrocytes." American Journal of Physiology-Cell Physiology 269, no. 1 (July 1, 1995): C96—C102. http://dx.doi.org/10.1152/ajpcell.1995.269.1.c96.

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The polyunsaturated fatty acids, arachidonic, linoleic, and linolenic acids, were potent blockers of regulatory volume decrease (RVD) and of the swelling-activated efflux of [3H]taurine, D-[3H]aspartate, [3H]inositol, and 125I (used as marker of Cl) from rat cerebellar astrocytes in culture. The monounsaturated oleic and ricinoleic acids and saturated fatty acids were ineffective. The amino acid and 125I fluxes were similarly inhibited by fatty acids, whereas inositol release was less sensitive. Polyunsaturated fatty acids appear to directly affect RVD in trypsinized astrocytes as the inhibition was immediate and fully reversible. Blockers of the arachidonic acid metabolic pathways, indomethacin (cyclooxygenase), esculetin (lipoxygenases), and metyrapone (P-450 monooxygenases), did not prevent the effect of arachidonic acid, suggesting that further metabolism is not required for displaying the effects of arachidonic acid on RVD and osmolyte fluxes. Some blockers of arachidonic acid metabolic pathways, such as nordihydroguaiaretic acid (lipoxygenases) and naphthoflavone (P-450 monooxygenases), also exhibited marked inhibitory effects on RVD and on osmolyte fluxes. The predominant arachidonic acid metabolite in astrocytes, 12-hydroxyeicosatetraenoic acid, did not affect RVD or osmolyte fluxes. These results suggest that arachidonic acid and other polyunsaturated fatty acids directly inhibit the permeability pathways correcting cell volume after swelling in cultured astrocytes.

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Buckley, B. J., and A. R. Whorton. "Arachidonic acid stimulates protein tyrosine phosphorylation in vascular cells." American Journal of Physiology-Cell Physiology 269, no. 6 (December 1, 1995): C1489—C1495. http://dx.doi.org/10.1152/ajpcell.1995.269.6.c1489.

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Arachidonic acid and its metabolites are important cellular mediators. In this study, we report a novel role for arachidonic acid in vascular cell signaling. We tested the effects of exogenous arachidonic acid on protein tyrosine phosphorylation in cultured vascular endothelial and smooth muscle cells. Arachidonic acid stimulated the phosphorylation of tyrosine-containing proteins of approximately 58, 93, and 120 kDa in the three cell types studied. This response was dose dependent, with a maximum effect observed with 40 microM arachidonic acid. Phosphorylation was rapid and transient, reaching a peak 0.5 min after the addition of arachidonic acid and returning to baseline by 8 min. A common set of protein substrates was phosphorylated in smooth muscle cells treated with the Ca(2+)-mobilizing agonist endothelin, concomitant with an increase in endogenous unesterified arachidonic acid. To determine whether the protein tyrosine phosphorylation was due to arachidonic acid or to a metabolite, we used inhibitors of cyclooxygenase, lipoxygenase, and epoxygenase pathways. Ibuprofen, nordihydroguaiaretic acid, eicosatriynoic and eicosatetraynoic acids, and 8-methoxypsoralen failed to inhibit the arachidonic acid-mediated response. We also found increased protein tyrosine phosphorylation after treatment with oleic, linolenic and gamma-linoleic acid. These results suggest a mechanism of protein tyrosine phosphorylation that is directly stimulated by unmetabolized unsaturated fatty acids.

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Cubero, Francisco Javier, and Natalia Nieto. "Arachidonic acid stimulates TNFα production in Kupffer cells via a reactive oxygen species-pERK1/2-Egr1-dependent mechanism." American Journal of Physiology-Gastrointestinal and Liver Physiology 303, no. 2 (July 15, 2012): G228—G239. http://dx.doi.org/10.1152/ajpgi.00465.2011.

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Kupffer cells are a key source of mediators of alcohol-induced liver damage such as reactive oxygen species, chemokines, growth factors, and eicosanoids. Since diets rich in polyunsaturated fatty acids are a requirement for the development of alcoholic liver disease, we hypothesized that polyunsaturated fatty acids could synergize with ethanol to promote Kupffer cell activation and TNFα production, hence, contributing to liver injury. Primary Kupffer cells from control and from ethanol-fed rats incubated with arachidonic acid showed similar proliferation rates than nontreated cells; however, arachidonic acid induced phenotypic changes, lipid peroxidation, hydroperoxides, and superoxide radical generation. Similar effects occurred in human Kupffer cells. These events were greater in Kupffer cells from ethanol-fed rats, and antioxidants and inhibitors of arachidonic acid metabolism prevented them. Arachidonic acid treatment increased NADPH oxidase activity. Inhibitors of NADPH oxidase and of arachidonic acid metabolism partially prevented the increase in oxidant stress. Upon arachidonic acid stimulation, there was a rapid and sustained increase in TNFα, which was greater in Kupffer cells from ethanol-fed rats than in Kupffer cells from control rats. Arachidonic acid induced ERK1/2 phosphorylation and nuclear translocation of early growth response-1 (Egr1), and ethanol synergized with arachidonic acid to promote this effect. PD98059, a mitogen extracellular kinase 1/2 inhibitor, and curcumin, an Egr1 inhibitor, blocked the arachidonic acid-mediated upregulation of TNFα in Kupffer cells. This study unveils the mechanism whereby arachidonic acid and ethanol increase TNFα production in Kupffer cells, thus contributing to alcoholic liver disease.

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Mandel, K. G., T. A. Bertram, M. K. Eichhold, S. C. Pepple, and M. J. Doyle. "Fatty Acid-mediated Gastroprotection Does Not Correlate with Prostaglandin Elevation in Rats Exposed to Various Chemical Insults." Veterinary Pathology 31, no. 6 (November 1994): 679–88. http://dx.doi.org/10.1177/030098589403100608.

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This study involved a comparison of activity of several long-chain fatty acids (arachidonic acid, dihomo-[γ]-linolenic acid, linoleic acid, and oleic acid) for protection against gastric mucosal damage elicited by taurocholic acid, acidified aspirin, and ethanol in rats. Each damaging agent induced gastric mucosal lesions in the corpus. Mucosal damage was induced by all agents, and all fatty acids protected the gastric mucosa; however, ethanol and arachidonic acid were the most potent damaging and protecting agents, respectively. Maximally protective doses for prevention of taurocholic acid-induced damage by arachidonic, dihomo-[γ]-linolenic, linoleic, and oleic acids were 50, 200, 100, and 200 mg/kg, respectively; however, 10 mg/kg arachidonic acid reduced lesion length by >50%, whereas minimally effective doses of the other fatty acids were ≥50 mg/kg. Similar potency differences were observed for fatty acid protection against acidified aspirin-induced gastric damage. Although all the fatty acids reduced macroscopic damage, histologic studies showed they did not totally eliminate surface mucosal damage. Microscopic analysis showed that treatment with dihomo-[γ]-linolenic acid or oleic acid attenuated depletion of neutral and acidic glycoproteins from the mucus neck cells of the gastric mucosa in response to exposure to taurocholic acid. Despite having similar gastroprotective activity, arachidonic, dihomo-[γ]-linolenic, linoleic, and oleic acids had very dissimilar abilities to elevate gastric mucosal E-series prostaglandins. Both arachidonic and dihomo-[γ]-linolenic acids elevated E-series prostaglandins, but arachidonic acid had 2–5-fold greater gastroprotective potency. Furthermore, oleic and linoleic acids, which had protective potency similar to that dihomo-[γ]-linolenic acid, did not significantly elevate prostaglandins. These studies failed to demonstrate an absolute correlation between prostaglandin elevation and gastroprotection. The results of this investigation suggest that prostaglandin elevation, although associated with gastroprotection, does not appear to be the sole mechanism for fatty acid-mediated protection of rat gastric mucosa.

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Needleman, P., J. Truk, B. A. Jakschik, A. R. Morrison, and J. B. Lefkowith. "Arachidonic Acid Metabolism." Annual Review of Biochemistry 55, no. 1 (June 1986): 69–102. http://dx.doi.org/10.1146/annurev.bi.55.070186.000441.

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Karara, Armando, Elizabeth Dishman, Harry Jacobson, J. R. Falck, and Jorge H. Capdevila. "Arachidonic acid epoxygenase." FEBS Letters 268, no. 1 (July 30, 1990): 227–30. http://dx.doi.org/10.1016/0014-5793(90)81014-f.

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McGiff, John C. "Arachidonic acid metabolism." Preventive Medicine 16, no. 4 (July 1987): 503–9. http://dx.doi.org/10.1016/0091-7435(87)90064-8.

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Dissertations / Theses on the topic "Arachidonic acid"

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Mantri, Padmaja. "Arachidonic acid aci-Reductone strategies : asymmetric synthesis of 2-hydroxytetronic acid antimetabolities /." The Ohio State University, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487848078452092.

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Berry, Elicia Bee Ean. "Intracellular signalling by arachidonic acid metabolites." Thesis, University of Auckland, 2006. http://hdl.handle.net/2292/3111.

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In intrauterine tissues, pro-inflammatory cytokines and prostaglandins (PGs) have been identified as key mediators in the maintenance of pregnancy and parturition. The rise in PGD2 detected in the amniotic fluid before labour prompted the research presented in this thesis which describes the effects of 15-deoxy Δ12,14 -prostaglandin J2 (15d-PGJ2), a non-enzymatic metabolite of PGD2, on amnion-derived WISH and JEG3 choriocarcinoma cells as models of the amnion and chorion trophoblasts, respectively.15d-PGJ2 induced apoptosis in both cell lines in a concentration-dependent fashion (2.5-10 µM). Apoptosis was characterised by condensation of chromatin (visualised after Hoechst 33342 staining), appearance of nucleosomal DNA fragmentation upon electrophoresis and flow cytometry analysis, and activation of caspase-3. Apoptotic cell death was inhibited in the presence of serum (0.5% w/v) and albumin, not serumderived growth factors (insulin growth factor (IGF)-1, IGF-2 or epidermal growth factor (EGF), was determined as the key survival factor. Since 15d-PGJ2 is reported to activate peroxisome proliferator activated receptor (PPAR)-γ, the activities of PPARs were assessed using JEG3 cells transfected with a PPAR-response element reporter construct (pTK-PPREx3-luc). The PPAR-γ-specific ligand, rosiglitazone, induced PPRE mediated activity in a concentration-dependent manner, while the PPAR-γ-specific irreversible inhibitor, GW9662, fully inhibited this induction. However, GW9662 only partially inhibited 15d-PGJ2-induced luciferase activity, suggesting that 15d-PGJ2 may also activate either of the other isoforms. The expressions of PPAR-α and -δ were identified in amnion, choriodecidua and placental membranes and PPAR-δ was significantly increased all tissues with labour. PPAR-α expression was reduced in chorio-decidua, but was significantly higher in placenta with labour. The changes observed with labour suggest that regulation of PPAR expression and function may have a role in the mechanisms that maintain pregnancy or initiate labour. The anti-inflammatory effects of 15d-PGJ2 were also investigated by measuring interleukin (IL)-1β-stimulated prostaglandin and cytokine productions by WISH cells after treatment with 15d-PGJ2 for 3 hours. 15d-PGJ2 exerted differential effects that were dependent upon its concentration. At low nanomolar physiologic concentrations (1-10 nM), 15d-PGJ2 inhibited IL-1β-stimulated PGE2, but not cytokine (IL-6/IL-8) production or cyclooxygenase (COX)-2 expression. This effect was attenuated by GW9662, by transfection with dominant negative PPAR constructs, and was reproduced by rosiglitazone. At micromolar (1-10 µM) concentrations, 15d-PGJ2 inhibited IL-1β-stimulated COX-2, PGE2 and cytokine productions and these effects were not blocked by GW9662 or mimicked by rosiglitazone. GW501516 (PPAR-δ agonist) also inhibited IL-1β-stimulated PGE2 production, but only at high concentrations (1 µM). IL-1β-induced NF-kB DNA binding activity was significantly inhibited by 15d-PGJ2 (10 µM) and GW501516 (1 µM), but increased by rosiglitazone (10 µM). In conclusion, this is the first report of an effect of 15d-PGJ2 at low nanomolar physiologic concentrations and 15d-PGJ2 mediates its actions through PPAR-γ (<0.1 µM) and PPAR-γ-independent(1-10 µM) pathways, the latter through inhibition of NF-kB and/or activation of PPAR-δ. Further studies on the effect of physiologic concentrations of 15d-PGJ2 on primary gestational tissues will provide understanding on the role(s) 15d-PGJ2 plays in fetal membrane remodelling and its involvement in the inflammatory processes associated with labour and parturition.
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Hewertson, S. J. "Arachidonic acid metabolism by liver and hepatoma." Thesis, Brunel University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379706.

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樊曉明 and Xiaoming Fan. "Arachidonic acid metabolism in apoptosis of gastric cancer." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B31241633.

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Fan, Xiaoming. "Arachidonic acid metabolism in apoptosis of gastric cancer." Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B22805448.

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Tsai, I.-Jung. "Perturbations of arachidonic acid metabolism in the metabolic syndrome." University of Western Australia. School of Medicine and Pharmacology, 2009. http://theses.library.uwa.edu.au/adt-WU2010.0065.

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[Truncated abstract] Arachidonic acid is oxidised in vivo by non-enzymatic (free radical) or enzymatic pathways (cyclooxygenase, lipoxygenase, and cytochrome P450) to form a range of biologically active eicosanoids. Specifically, arachidonic acid is metabolised by cytochrome P450 -hydroxylase to produce vasoactive 20-hydroxyeicosatetraenoic acid (20-HETE), and by 5-lipoxygenase to produce proinflammatory leukotriene B4 (LTB4), which can further be metabolised by -hydroxylase to from 20-OH-LTB4 and 20-COOH-LTB4. F2-Isoprostanes (F2-IsoPs) are produced through free radical attack on arachidonic acid and have been recognised as the most reliable markers of lipid peroxidation in vivo. The metabolic syndrome (MetS) is characterised by abdominal obesity, hypertension, insulin resistance, glucose intolerance, and dyslipidemia. It is associated with low-grade inflammation and oxidative stress and an increased risk of developing cardiovascular diseases. Dietary weight loss is strongly recommended for the management of the MetS and can potentially minimise the risk of cardiovascular diseases and diabetes in individuals with the MetS. Little is known regarding the role of these arachidonic acid metabolites in the MetS and the effect of weight loss on their metabolism. Chapter three comprised of three in vitro studies aimed to examine 20-HETE synthesis in human blood cells. 20-HETE acts as a second messenger for vasoconstrictor actions of angiotensin II (Ang II) and endothelin-1 (ET-1) in renal and mesenteric beds. Human neutrophils and platelets are integral to the inflammatory process. ... Production of LTB4 and 20-OH-LTB4 was significantly lower compared with controls (P<0.005) and remained so after adjustment for neutrophil count (P<0.05).The weight loss intervention resulted in a 4.6kg reduction in body weight and a 6.6cm decrease in waist circumference and a significant increase in LTB4 and 20-OH- LTB4 in the weight loss group. Chapter Five continued to investigate the role of other arachidonic acid metabolites, 20-HETE and F2-IsoPs in the MetS and the effect of weight loss. In the case-control study (Human study 1), plasma and urinary 20-HETE and F2-IsoPs were significantly elevated in the MetS group, but no significant difference was found in stimulated-neutrophil 20-HETE. A significant gender x group interaction was observed in that women with the MetS had higher urinary 20-HETE and F2-IsoPs compared to controls (P<0.0001). In a randomised controlled trial (Human study 2), relative to the weight- maintenance group, a 4.6 kg loss in weight resulted in a 2 mmHg fall in blood pressure but did not alter the production of 20-HETE or F2-IsoPs. No significant differences were shown in 20-HETE released from stimulated-neutrophils before and after weight loss. 20-HETE and oxidative stress may be important mediators of cardiovascular disease risk in the MetS. Although a 4% reduction in body weight reduced BP, there were no changes in plasma or urinary 20-HETE or F2-IsoPs. In summary, in vitro studies show that human neutrophils and platelets can produce 20-HETE in response to Ang II and ET-1, and human studies demonstrate that the presence of MetS has a significant impact on arachidonic acid metabolism and effective weight loss can restore leukocyte synthesis of LTB4.

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Mollapour, Elahe. "The role of arachidonic acid mobilisation in myeloid cells." Thesis, University College London (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313822.

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Saunders, Royal Duane. "Arachidonic acid and lipid metabolism following spinal cord injury /." The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487260859496213.

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CHIESA, FRANCESCO. "SYNTHETICAL STUDIES ON ARACHIDONIC ACID METABOLITES FOR DIAGNOSTIC PURPOSES." Doctoral thesis, Università degli studi di Pavia, 2017. http://hdl.handle.net/11571/1203279.

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Prostaglandins (PGs) are the principal metabolites of arachidonic acid. The basic prostaglandin skeleton is that of a cyclized C20 fatty acid containing a cyclopentane ring, a C7 side-chain with the carboxyl function (α-chain), and a C8 side-chain with the methyl terminus (ω-chain). They are now known to occur widely in animal tissues, but only in tiny amounts, and they have been found to exert a wide variety of pharmacological effects on humans and animals. The quantification of PGs in biological fluids is often affected by artifacts or ex vivo generation of these molecules during the sampling. The measurement of free eicosanoids and their metabolites in urine is a non-invasive and representative method for the determination of their systemic production. For these reasons the synthesis of prostaglandins derivatives is important to obtain useful standards for diagnostic purposes. With this study we propose a new synthesis of the PGE2-urinary metabolite and the synthetical study on the probable urinary metabolite of the 15d-PGJ2.Both synthetical approaches use the TBS-Corey Aldehyde as principal building block that permit easy and flexible three component stnthesis.
Prostaglandins (PGs) are the principal metabolites of arachidonic acid. The basic prostaglandin skeleton is that of a cyclized C20 fatty acid containing a cyclopentane ring, a C7 side-chain with the carboxyl function (α-chain), and a C8 side-chain with the methyl terminus (ω-chain). They are now known to occur widely in animal tissues, but only in tiny amounts, and they have been found to exert a wide variety of pharmacological effects on humans and animals. The quantification of PGs in biological fluids is often affected by artifacts or ex vivo generation of these molecules during the sampling. The measurement of free eicosanoids and their metabolites in urine is a non-invasive and representative method for the determination of their systemic production. For these reasons the synthesis of prostaglandins derivatives is important to obtain useful standards for diagnostic purposes. With this study we propose a new synthesis of the PGE2-urinary metabolite and the synthetical study on the probable urinary metabolite of the 15d-PGJ2.Both synthetical approaches use the TBS-Corey Aldehyde as principal building block that permit easy and flexible three component stnthesis.

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溫志友 and Zhiyou Wen. "A high yield and productivity strategy for eicosapentaenoic acid production by the diatom Nitzschia laevis in heterotrophic culture." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31242418.

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Books on the topic "Arachidonic acid"

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1931-, Hegyeli Ruth Johnsson, and United States-Italy Symposium on "Arachidonic Acid Metabolites and Atherosclerosis" (1985 : Houston, Tex.), eds. Arachidonic acid metabolites. New York: Raven Press, 1985.

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Piomelli, Daniele. Arachidonic Acid in Cell Signaling. Berlin, Heidelberg: Springer Berlin Heidelberg, 1996. http://dx.doi.org/10.1007/978-3-662-05807-7.

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Lands, William E. M., ed. Biochemistry of Arachidonic Acid Metabolism. Boston, MA: Springer US, 1985. http://dx.doi.org/10.1007/978-1-4613-2597-0.

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Arachidonic acid in cell signaling. Austin, Tex: R.G. Landes Co., 1996.

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Lands, William E. M., 1930-, ed. Biochemistry of arachidonic acid metabolism. Boston: Nijhoff, 1985.

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M, Fischer Susan, and Slaga Thomas J, eds. Arachidonic acid metabolism and tumor promotion. Boston: Nijhoff, 1985.

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J, Marnett Lawrence, ed. Arachidonic acid metabolism and tumor initiation. Boston: Nijhoff, 1985.

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Fischer, Susan M., and Thomas J. Slaga, eds. Arachidonic Acid Metabolism and Tumor Promotion. Boston, MA: Springer US, 1985. http://dx.doi.org/10.1007/978-1-4613-2605-2.

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Marnett, Lawrence J., ed. Arachidonic Acid Metabolism and Tumor Initiation. Boston, MA: Springer US, 1985. http://dx.doi.org/10.1007/978-1-4613-2611-3.

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Morgan, Androula. Aspects of uterine arachidonic acid metabolism. Uxbridge: Brunel University, 1985.

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Book chapters on the topic "Arachidonic acid"

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Bährle-Rapp, Marina. "Arachidonic Acid." In Springer Lexikon Kosmetik und Körperpflege, 43. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-71095-0_763.

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Bährle-Rapp, Marina. "Arachidonic Acid." In Springer Lexikon Kosmetik und Körperpflege, 43. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-71095-0_764.

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Biswas-Fiss, Esther E., Stephanie Affet, Malissa Ha, Takaya Satoh, Joe B. Blumer, Stephen M. Lanier, Ana Kasirer-Friede, et al. "Arachidonic Acid." In Encyclopedia of Signaling Molecules, 135. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4419-0461-4_100069.

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van Kranen, Henk J., and Christine L. E. Siezen. "Arachidonic Acid Pathway." In Encyclopedia of Cancer, 1–6. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-27841-9_380-3.

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van Kranen, Henk J., and Christine L. E. Siezen. "Arachidonic Acid Pathway." In Encyclopedia of Cancer, 342–47. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-662-46875-3_380.

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van Kranen, Henk J., and Christine L. E. Siezen. "Arachidonic Acid Pathway." In Encyclopedia of Cancer, 260–65. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-16483-5_380.

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Piomelli, Daniele. "The Arachidonic Acid Cascade." In Arachidonic Acid in Cell Signaling, 1–14. Berlin, Heidelberg: Springer Berlin Heidelberg, 1996. http://dx.doi.org/10.1007/978-3-662-05807-7_1.

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Quilley, J., and J. C. McGiff. "Renal arachidonic acid metabolism." In Eicosanoids in the Cardiovascular and Renal Systems, 16–33. Dordrecht: Springer Netherlands, 1988. http://dx.doi.org/10.1007/978-94-009-1285-4_2.

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Wallace, John L. "The Arachidonic Acid Pathway." In Drug Development, 1–20. Totowa, NJ: Humana Press, 2000. http://dx.doi.org/10.1007/978-1-59259-202-9_1.

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Piomelli, Daniele. "Biosynthesis, Storage and Mobilization of Arachidonic Acid." In Arachidonic Acid in Cell Signaling, 15–53. Berlin, Heidelberg: Springer Berlin Heidelberg, 1996. http://dx.doi.org/10.1007/978-3-662-05807-7_2.

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Conference papers on the topic "Arachidonic acid"

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Schick, Paul K., Barbara P. Schick, and Pat Webster. "THE EFFECT OF OMEGA 3 FATTY ACIDS ON MEGAKARYOCYTE ARACHIDONIC ACID METABOLISM." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1642953.

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Dietary omega 3 polyunsaturated fatty acids are thought to prevent atherosclerosis. It has been proposed that omega 3 fatty acids modify platelet arachidonic acid (20:4) metabolism and platelet function and thereby reduce the incidence of thrombosis. We have previously shown that megakaryocytes (MK), like platelets, contain large amounts of esterified 20:4. The study addresses the following questions: 1) Do omega 3 fatty acids have a primary action on 20:4 metabolism in MK rather than in platelets. 2) Do omega 3 marine oils, docosahexaenoic acid (22:6) and eicosapentaenoic acid (20:5), have a different effect on megakaryocyte 20:4 metabolism than does alpha linolenic acid (18:3), the major omega-3 fatty acid present in normal diets? 3) How do omega-3 fatty acids modify megakaryocyte 20:4 acid metabolism? MK and platelets were isolated from guinea pigs. Isolated cells were incubated with radiolabeled 20:4 acid and unlabeled 18:3, 20:5 or 22:6. Incubations were terminated by lipid extraction, lipid classes were separated by thin-layer chromatography and the incorporation of radiolabeled 20:4 into lipid species was measured by scintillation spectrometry.MK (106) can incorporate about 4 times more 20:4 than 109 platelets. We have previously shown that 20:4 is incorporated into all endogenous pools of 20:4 in MK while platelets appear to have a limited capacity to incorporate 20:4 into phosphatidyl-ethanolamine (PE). Marine oils, 22:6 and 20:5, had similar effects on the incorporation of radiolabeled 20:4 in MK. Both marine oils reduced the total uptake of 20:4 in megakaryocytes but the reduction occured primarily in PE and phosphatidylserine (PS) rather than in phosphatidylcholine (PC) and phosphatidylinositol (PI). Both 20:5 and 22:6 caused a 50% reduction in the incorporation of radiolabeled 20:4 into megakaryocyte PE and PS while only a 20% reduction into PC and PI. There was a striking difference in the effect of 18:3. Even though the incubation of megakaryocytes with 18:3 reduced the uptake of 20:4, the distribution of the incorporated 20:4 in phospholipids of megakaryocytes incubated with 18:3 was similar to that in controls. Thus, 18:3 did not have a selective effect on the incorporation of 20:4 into PE or PS. Whereas megakaryocyte 20:4 metabolism was significantly affected by omega-3 fatty acids, the incubation of guinea pig or human platelets with 22:6, 20:5 or 18:3 did not result in any alteration of the incorporation of 20:4 into platelet phospholipids.20:4 may be initially incorporated into megakaryocyte PC and subsequently transfered to PE and other phospholipids. Omega 3 marine oils, 20:5 and 22:6, appear to have a selective action on the incorporation or transfer of 20:4 into PE and PS. One mechanism for these observations would be an effect of marine oils on megakaryocyte acyltransferase and/or transacylases. Omega 3 linolenic acid appears to reduce the uptake of 20:4 but does not affect the transfer of 20:4 into PE and PS since there was no selective inhibition of uptake into PE or other megakaryocyte phospholipids. The observation that marine oils did not have any effect on 20:4 metabolism in platelets indicated that omega 3 polyunsaturated fatty acids primarily affect megakaryocytes. This phenomenon may result in the production of platelets with abnormal content and compartmentalization of arachidonic acid. The localization of 20:4 in different pools in these platelets could influence the availability of esterified 20:4 for the production of thromboxanes and other eicosanoids. Another implication of the study is that omega 3 fatty acids may have a greater effect on precursor cells than on differentiated cells and tissues and influence cellular maturation.

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Gray, E., P. J. Kerry, S. J. Edwards, and T. W. Barrowcliffe. "PROCOAGULANT ACTIVITY OF PLATELET LIPCKYGENASE PRODUCTS." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643945.

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Arachidomc acid is metabolised by cyclo-oxygenase and lipoxygenase enzymes in platelets. Cyclo-oxygenase produces the highly pro-aggregatory thromboxane A2 but the physiological significance of the lipoxygenase pathway in platelets remains uncertain. Arachidonic acid can also be converted to biologically active peroxides by free radical induced autoxidation, and previous studies have shown that such products generate large amounts of thrombin in platelet-free plasma, via their interaction with plasma lipoproteins.In the present study, we have investigated the procoagulant activities of platelet lipoxygenase products and compared them with autoxidised arachidonic acid. Platelet concentrates were incubated with arachidonic acid and indomethacin for 30 minutes and the products extracted with ethyl acetate. After drying down, reconstitution in ethanol and partitioning with petrolehm ether to remove unchanged acid, contaminating platelet phospholipid was removed by TLC. By inclusion of 14C-arachidonic acid, average conversion was estimated as 17% in six experiments.The products promoted the generation of large amounts of thrombin in platelet-free plasma; the peak thrombin averaged 23.1 iu/ml with three different batches. The activity was similar to that of a procoagulant phospholipid (PL) but, unlike PL, the lipoxygenase products did not shorten the kaolin recalcification time, confirming the absence of platelet PL contamination, and were virtually inactive in lipoprotein-free plasma. The activity of the lipoxygenase products was therefore similar to that of autoxidised arachidonic acid in its requirement for plasma lipoproteins. Further TLC separation of the products showed that the activity was associated with a minor component of the mixture which was active at plasma concentrations below 10 μg/ml.These results suggest a possible role for platelet lipoxygenase products in the coagulation system and provide a novel link between platelets, lipoproteins and coagulation which could be inportant in the pathogenesis of atherosclerosis.

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Nakashima, S., T. Tohmatsu, H. Hattori, A. Suganuma, and Y. Nozawa. "EVIDENCE FOR INVOLVEMENT OF GTP-BINDING PROTEIN IN ARACKIDONIC ACID RELEASE BY PHOSPHOLIPASE A2 IN PERMEABILIZED HUMAN PLATELETS." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644631.

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Platelet activation is accompanied by the active metabolism of membrane phospholipids. Phosphoinositide breakdown by phospholipase C generates second messengers; inositol trisphosphate and diacylglycerol. Recently, it is suggested that GTP-binding protein is linked to the activation of phospholipase C as is true for adenylate cyclase. Although it is known that the receptor stimulation by agonists leads to generation of arachidonic acid, its molecular mechanism has not yet been clear. However, several studies in neutrophils and mast cells using pertussis toxin, have shown the possibility that a GTP-binding protein may act as an intermediary unit component between the receptor and phospholipase A2. The present study was therefore designed to examine the effect of GTP and its analogue GTPγS on the arachidonic acid release in saponin-permeabilized human platelets. GTP or GTPγS alone caused a small but significant liberation of arachidonic acid in permeabilized cells but not in intact cells. GTP or GTPγS was found to enhance thrombin-induced [3H]arachidonic acid release in saponi n-permeabi li zed human platelets. The release of arachidonic acid has been ascribed to activity of phospholipase A2 and/or to sequential action of phospholipase C and diacylglycerol lipase. Inhibitors of phospholipase C (neomycin)/ diacylglycerol lipase (RHC 80267) pathway of arachidonate liberation did not reduce the level of the [3H]arachidonic acid release. The loss of [3H]arachidonate radioactivity from phosphatidylcholine was almost complementary to the increment of released [3H]arachidonic acid, suggesting thrombin-induced hydrolysis of phosphatidylcholine by phospholipase A2. Although phospholipase A2 usually are described as having a requirement for calcium, the effect of GTPγS was more evident at lower calcium concentrations (buffer>0.1 mM>1.0 mM). These data thus indicate that release of arachidonic acid by phospholipase A2 in saponin-treated platelets is closely linked to GTP-binding protein which may decrease the calcium requirement for phospholipase A2 activation.

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Hatmi, M., A. Del Maschio, J. Lefort, G. De Gaetano, B. B. Varqaftiq, and C. Cerletti. "EFFECTS OF SULFINPYRAZONE AND ITS METABOLITE G25671 ON PLATELET ACTIVATION AND DESENSITIZATION AND ON BRONCHOCONSTRICTION INDUCED BY THE PROSTAGLANDIN ENDOPEROXIDE ANALOGUE U46619." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643854.

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In previous studies we have found (Br. 3. Pharmac. 85, 849, 1985) that a) human platelets pre-exposed to arachidonic acid or to the endoperoxide analogue, U46619 and then washed and resuspended, fail to respond to a second challenge by both arachidonic acid and U46619; b) desensitization by arachidonic acid and U46619 occurs at a site sensitive to endoperoxides / thromboxane (Tx) receptor antagonists; c) the desensitizing effects of U46619 are direct, whereas those of arachidonic acid are mediated by a cyclooxygenase-dependent metabolite. Sulfinpyrazone (100 μM) and its thioether metabolite G25671 (50 μM) are known to suppress arachidonic acid-induced platelet aggregation and TxB2 formation (Eur. 3. Pharmac, 101, 209, 1984). We now demonstrate that the presence of sulfinpyrazone or G25671 during platelet exposure to arachidonic acid or U46619 prevents desensitization. Platelet activation by the endoperoxide analogue U46619 is also prevented by sulfinpyrazone or G25671 (0.3-1 mM). The threshold aggregating concentrations of arachidonic acid and U46619 in healthy subjects before and after oral treatment with sulfinpyrazone were elevated by 2-3 fold and a good correlation between ex vivo and in vitro findings was established. We finally examined the actions of sulfinpyrazone and G25671 on the bronchoconstriction in vivo and parenchymal lung strip contraction in vitro induced by U46619. Neither drug had any preventive effect.Our results demonstrate that sulfinpyrazone and its metabolite G25671 are not only cyclooxygenase inhibitors but can also act as endoperoxide/Tx antagonists and indicate clearly that antagonism of U46619 by both drugs is selective for platelets.

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Du, Tianchuan, Shuju Bai, and Ebrahim Khosravi. "Docking arachidonic acid to 8R-lipoxygenase using internal coordinate mechanics." In the First ACM International Conference. New York, New York, USA: ACM Press, 2010. http://dx.doi.org/10.1145/1854776.1854852.

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Mingmin Bai, E. Khosravi, and Shuju Bai. "Docking arachidonic acid into human 5/12-lipoxygenase using ICM." In 2011 IEEE International Conference on Bioinformatics and Biomedicine Workshops (BIBMW). IEEE, 2011. http://dx.doi.org/10.1109/bibmw.2011.6112526.

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Gladwin, A. M., and J. Martin. "ARACHIDONIC ACID (AA) INDUCED AGGREGATION OF RAT PRO- MEGAKARYOBLASTS (RPM)." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643542.

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Platelet aggregation can be induced in vitro by a variety of platelet agonists acting upon membrane receptors. Since platelets have only a limited ability to synthesise proteins, these receptors must be present in megakaryocytes. This was investigated using an eternal line line of RPMs. Cells were suspended in rat platelet free plasma (PFP) at a concentration of 105 cells ml-1 . 200μl aliquots of this were placed in a light aggregometer. For this suspension, and for an aliquot of PFP, light transmission was adjusted to zero and 100% respectively. Addition of ADP (plasma concentrations 1-100μM), thrombin (0.5-5 I.U. ml-1 ), and adrenaline (0.1-1 I.U. ml-1 ) to the suspension caused no change in transmission. However, addition of AA (1.5-6mM) increased light transmission, indicating RPM aggregation. Radioimmunoassay (RIA) on the resultant supernatant showed no thromboxane B2 was produced. Scanning and transmission electron microscopy showed the aggregate to be composed of non-lysed cells. Aggregation of RPMs was not inhibited by preincubation with PGL (1500ng ml-1 ) indomethacin (100μg ml-1 ) or fenoprofen (1002μg ml-1 ). However, preincubation with aspirin (30μM) blocked aggregation.These results indicate that RPMs can aggregate in response to AA. Mechanism of this is unlike that observed for platelets, since PGI2, indomethacin and fenoprofen did not block aggregation. The response was only inhibited by aspirin. Indomethacin, fenoprofen and aspirin are all known inhibitors of cyclo-oxygenase. In addition, aspirin also blocks 12-lipoxygenase. Therefore, this may suggest that the effect of AA on RPMs is mediated via 12-lipoxygenase pathway. Further investigations are in progress

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Riepl, J., K. Schilcher, S. Vlaic, R. Guthke, M. Melter, and TS Weiss. "Palmitic acid treatment alters expression of arachidonic-acid pathway associated genes in hepatoma cells linking fatty acids to inflammation." In 35. Jahrestagung der Deutschen Arbeitsgemeinschaft zum Studium der Leber. Georg Thieme Verlag KG, 2019. http://dx.doi.org/10.1055/s-0038-1677181.

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"ASSOCIATION OF FREE FATTY ACID CONCENTRATIONS WITH GLUCOSE LEVELS IN BOSNIAN SUBJECTS." In RAD Conference. RAD Centre, Niš, Serbia, 2023. http://dx.doi.org/10.21175/radproc.2023.09.

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Although there is considerable evidence suggesting a strong association of glucose, glycated hemoglobin and fatty acid levels with Type 2 diabetes mellitus (T2D), a limited number of studies have examined the association of individual fatty acids with disease progression. Acutely elevated plasma fatty acids stimulate insulin secretion while chronically elevated plasma fatty acids alter and disrupt insulin secretion. Furthermore, free fatty acids (FFA) are known to interfere with normal glucose homeostasis and affect pancreatic β-cell dysfunction. The study included 24 patients with newly diagnosed type 2 diabetes and 27 healthy controls, and analysis of the level of glucose and glycated hemoglobin was done by routine methods. The concentration of individual FFA was determined by gas chromatography with mass spectrometry detection. The results showed statistically significant differences in glucose, HbA1c, lipid profile, palmitic, linolenic, arachidonic, arachidonic, behenic acid as well as in DHA levels in all participants. In healthy subjects, no significant correlation was found between glucose and individual free fatty acids but a negative correlation was observed between DHA and glycated hemoglobin (p<0.05). Newly diagnosed diabetics showed a negative significant association between glucose and lauric acid concentrations, and also the association of glycated hemoglobin with myristic acid levels (p<0.01 and p<0.05, respectively). These data indicate the association of different types of free fatty acids with glucose levels and their control in the serum of healthy and newly diagnosed type 2 diabetics, and therefore indicate the importance of monitoring glucose levels as well as glycated hemoglobin with concentrations of individual free fatty acids in the progression of diabetes.

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Mointire, V. L., A. J. Frangos, G. B. Rhee, G. S. Eskin, and R. E. Hall. "RHEOLOGY AND CELL ACTIVATION." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643988.

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The subject of this work is to examine the hypothesis that some sublytic levels of mechanical perturbation of cells can stimulate cell metabolism. As a marker metabolite, we have chosen arachidonic acid. Principal metabolites for platelets include the cyclooxygenase product thromboxane A2(TXA2) and the lipoxygenase product 12-hydroperoxy-eicosatetraenoic acid (12-HPETE). Polymorphonuclear leukocytes (PMNLs) initally produce principally 5-HPETE, somtimes leading to the formation leukotrienes, though many other metabolites of arachidonic acid have been isolated from activated neutrophils. Human umbilical vein endothelial cells utilize arachidonic acid to produce mainly prostaglandin I2(PGI2). All of these metabolites are biologically active and modulate cell function - sometimes in quite contrasting ways. We will show that levels of sublytic mechanical stress exposure can stimulate arachidonic acid metabolism in all three of the cell types mentioned above. The biological implications of this stress/metabolism coupling may be quite far reaching.Human platelets, leukocytes and endothelial cells all appear to be sensitive to mechanical stress induced activation of arachidonic acid metabolism. Sheared PRP exhibited greatly increased synthesis of 12-HETE and surprisingly little thromboxane B2 production. This indicates that shear stress stimulation of platelets may produce quite different arachidonic acid metabolism than that seen with many direct chemical stimuli, such as thrombin or collagen.Our data demonstrate that a substance derived from shear induced platelet activation may activate the C-5 lipoxygenase of human PMNL under stress, leading to the production of LTB4. We hypothesize that this substance maybe 12-HPETE. LTB4 is known to be a very potent chemotactic factor and to induce PMNL aggregation and degranulation. Our studies provide further evidence that lipoxygenase products of one cell type can modulate production of lipoxygenase products in a second cell type, and that shear stress can initiate cell activation. This kind of coupling could have far reaching implications in terms of our understanding of cell/cell interaction in flowing systems, such as acute inflammation, artificial organ implantation and tumor metastasis.The data on PGI2 production by endothelial cells demonstrate that physiological levels of shear stress can dramatically increase arachidonic acid metabolism. Step increases in shear stress lead to a burst in production of PGI2 which decayed to a steady state value in several minutes. This longer term stimulation of prostacyclin production rate increased linearly with shear stress over the range of 0-24 dynes/cm2. In addition, pulsatile flow of physiological frequency and amplitude caused approximately 2.4 times the PGI2 production rate as steady flow with the same mean stress. Although only PGI2 was measured, it is likely that other arachidonic acid metabolites of endothelial cells are also affected by shear stress.The ability of cells to respond to external stimuli involves the transduction of a signal across the plasma membrane. One such external stimulus appears to be fluid shear stress. Steady shear flow induces cell rotation in suspended cells, leading to a periodic membrane loading, with the peak stress proportional to the bulk shear stress. On anchorage-dependent cells, such as endothelial cells, steady shear stress may act by amplifying the natural thermal or Brownian fluttering or rippling of the membrane. There are several possible mechanisms by which shear stress induced membrane perturbation could mimic a hormone/receptor interaction, leading to increased intracellular metabolism. Shear stress may induce increased phospholipase C activity, caused by translocation of the enzyme, increased substrate (arachidonic acid) pool availability to phospholipase C (particularly from that stored in phosphoinositols) due to shear-induced membrane movements or changes in membrane fluidity, direct activation of calcium - activated phospholipase A2 by increased membrane calcium ion permeability, or most probably by a combination of these mechanisms.

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Reports on the topic "Arachidonic acid"

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Crosland, Richard D. Effect of Arachidonic Acid on Twitch Tension of the Rat Phrenic Nerve- Diaphragm. Fort Belvoir, VA: Defense Technical Information Center, January 1992. http://dx.doi.org/10.21236/ada265570.

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Meidan, Rina, and Robert Milvae. Regulation of Bovine Corpus Luteum Function. United States Department of Agriculture, March 1995. http://dx.doi.org/10.32747/1995.7604935.bard.

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The main goal of this research plan was to elucidate regulatory mechanisms controlling the development, function of the bovine corpus luteum (CL). The CL contains two different sterodigenic cell types and therefore it was necessary to obtain pure cell population. A system was developed in which granulosa and theca interna cells, isolated from a preovulatory follicle, acquired characteristics typical of large (LL) and small (SL) luteal cells, respectively, as judged by several biochemical and morphological criteria. Experiments were conducted to determine the effects of granulosa cells removal on subsequent CL function, the results obtained support the concept that granulosa cells make a substaintial contribution to the output of progesterone by the cyclic CL but may have a limited role in determining the functional lifespan of the CL. This experimental model was also used to better understand the contribution of follicular granulosa cells to subsequent luteal SCC mRNA expression. The mitochondrial cytochrome side-chain cleavage enzyme (SCC), which converts cholesterol to pregnenolone, is the first and rate-limiting enzyme of the steroidogenic pathway. Experiments were conducted to characterize the gene expression of P450scc in bovine CL. Levels of P450scc mRNA were higher during mid-luteal phase than in either the early or late luteal phases. PGF 2a injection decreased luteal P450scc mRNA in a time-dependent manner; levels were significantly reduced by 2h after treatment. CLs obtained from heifers on day 8 of the estrous cycle which had granulosa cells removed had a 45% reduction in the levels of mRNA for SCC enzymes as well as a 78% reduction in the numbers of LL cells. To characterize SCC expression in each steroidogenic cell type we utilized pure cell populations. Upon luteinization, LL expressed 2-3 fold higher amounts of both SCC enzymes mRNAs than SL. Moreover, eight days after stimulant removal, LL retained their P4 production capacity, expressed P450scc mRNA and contained this protein. In our attempts to establish the in vitro luteinization model, we had to select the prevulatory and pre-gonadotropin surge follicles. The ratio of estradiol:P4 which is often used was unreliable since P4 levels are high in atretic follicles and also in preovulatory post-gonadotropin follicles. We have therefore examined whether oxytocin (OT) levels in follicular fluids could enhance our ability to correctly and easily define follicular status. Based on E2 and OT concentrations in follicular fluids we could more accurately identify follicles that are preovulatory and post gonadotropin surge. Next we studied OT biosynthesis in granulosa cells, cells which were incubated with forskolin contained stores of the precursor indicating that forskolin (which mimics gonadotropin action) is an effective stimulator of OT biosynthesis and release. While studying in vitro luteinization, we noticed that IGF-I induced effects were not identical to those induced by insulin despite the fact that megadoses of insulin were used. This was the first indication that the cells may secrete IGF binding protein(s) which regonize IGFs and not insulin. In a detailed study involving several techniques, we characterized the species of IGF binding proteins secreted by luteal cells. The effects of exogenous polyunsaturated fatty acids and arachidonic acid on the production of P4 and prostanoids by dispersed bovine luteal cells was examined. The addition of eicosapentaenoic acid and arachidonic acid resulted in a dose-dependent reduction in basal and LH-stimulated biosynthesis of P4 and PGI2 and an increase in production of PGF 2a and 5-HETE production. Indomethacin, an inhibitor of arachidonic acid metabolism via the production of 5-HETE was unaffected. Results of these experiments suggest that the inhibitory effect of arachidonic acid on the biosynthesis of luteal P4 is due to either a direct action of arachidonic acid, or its conversion to 5-HETE via the lipoxgenase pathway of metabolism. The detailed and important information gained by the two labs elucidated the mode of action of factors crucially important to the function of the bovine CL. The data indicate that follicular granulosa cells make a major contribution to numbers of large luteal cells, OT and basal P4 production, as well as the content of cytochrome P450 scc. Granulosa-derived large luteal cells have distinct features: when luteinized, the cell no longer possesses LH receptors, its cAMP response is diminished yet P4 synthesis is sustained. This may imply that maintenance of P4 (even in the absence of a Luteotropic signal) during critical periods such as pregnancy recognition, is dependent on the proper luteinization and function of the large luteal cell.

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Fields, Michael J., Mordechai Shemesh, and Anna-Riitta Fuchs. Significance of Oxytocin and Oxytocin Receptors in Bovine Pregnancy. United States Department of Agriculture, August 1994. http://dx.doi.org/10.32747/1994.7568790.bard.

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Oxytocin has multiple actions in bovine reproductive tract and it was our purpose to determine the nature of these actions and their significance for the physiology of bovine reproduction. The bovine oxytocin receptors (OTR) gene was cloned and its expression studied during the cycle and pregnancy. OTR mRNA changed in parallel with OTR with control occurring mainly at the transcriptional level. However, the endocrine regulation of OTR were found in endometrium and cervical mucosa at estrus and at parturition. In both tissues OTR were suppressed in the luteal phase and early pregnancy. Whereas cervical OTR remained suppressed throughout pregnancy, endometrial OTR began to increase soon after implantation and reached higher concentrations in midpregnancy than at estrus. OTR in caruncles did not increase until third trimester, and OTR in cervical mucosa, cotyledons and fetal membranes increased only at term. Myometrial OTR showed less variation and OTR were present throughout the cycle and pregnancy but increased significantly during mid- and late pregnancy. OTR were localized in endometrial epithelial cells and lumina epithelial cells of cervical mucosa as determined by immunohistochemistry. Endometrial OTR were functional throughout pregnancy and mediated PGF release from day 50 onwards in a receptor density related manner. OTR in cervical mucosa mediated PGE release both in vivo and in vitro, as shown in cyclic cows. The ontogeny of uterine OTR was studied from third trimester fetal stage until puberty. OTR were present in endometrium and cervical mucosa in high concentrations throughout this period; myometrial OTR began to increase somewhat later but also reached adult values by 6-mo of age. In the prepuberal heifers OT injections failed to initiate PGF2a, release. The influence of steroids on the effect of OT was examined. Ovariectomy and E2 were without effect, but P4 with or without E2 induced a massive PGF2a release in response to OT in spite of reduced OTR. Bovine cyclooxygenases (COX-1 and COX-2) were cloned and their expression studied in the endometrium of prepuberal heifers and pregnant cows. Untreated and E2 treated prepuberal heifers did not express COX-2 but P4 treated heifers did express the mRNA for COX-2, albeit weakly. During the second half of pregnancy COX-2 mRNA was strongly expressed in cotyledons and somewhat less in caruncles, whereas endometrium, myometrium and cervical mucosa showed only weak, if any, COX-2 mRNA under basal conditions. However, 2 h after OT injection significant increases in COX-2 mRNA were found in endometrial RNA. Thus OT is capable of inducing the expression of the inducible COX-2 gene, and hence the conversion of arachidonic acid to prostanoids. The results indicate that the functions of OT are numerous and probably essential for successful pregnancy and parturition.

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