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Mark A Sheridan - One of the best experts on this subject based on the ideXlab platform.
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Effects of insulin, glucagon, and Somatostatin on the release of Somatostatin-25 and Somatostatin-14 from rainbow trout, Oncorhynchus mykiss, pancreatic islets in vitro.
General and comparative endocrinology, 1995Co-Authors: C. D. Eilertson, Jeffrey D. Kittilson, Mark A SheridanAbstract:Somatostatins are a diverse family of peptides known to modulate insulin and glucagon secretion as well as to stimulate glycogenolysis and lipolysis in salmonid fish. In this study, Brockmann bodies (bisected to yield hemi-islets) isolated from rainbow trout, Oncorhynchus mykiss, were used to study the effects of insulin, glucagon, and Somatostatin at various concentrations of glucose (1, 5, and 10 mM) on pancreatic Somatostatin release. The release of Somatostatin-25, the most predominate form of Somatostatin in salmonid pancreas, was stimulated by insulin in the presence of 1 and 5 mM glucose but not in the presence of 10 mM glucose, whereas glucagon stimulated Somatostatin-25 release only in the presence of high (10 mM) glucose. Somatostatin-25 release also was stimulated by Somatostatin-14. The secretion of Somatostatin-14 was suppressed by insulin in the presence of 5 and 10 mM glucose and was stimulated by glucagon in the presence of high (10 mM) glucose. These results indicate that insulin, glucagon, and Somatostatin-14 are regulators of Somatostatin-14 and Somatostatin-25 pancreatic release in rainbow trout and that these effects are modulated by glucose.
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Effects of Somatostatin-25 on lipid mobilization from rainbow trout, Oncorhynchus mykiss, liver and adipose tissue incubated in vitro. Comparison with Somatostatin-14
Journal of Comparative Physiology B-biochemical Systemic and Environmental Physiology, 1994Co-Authors: C. D. Eilertson, Mark A SheridanAbstract:The physiological effects of the pancreatic peptides Somatostatin-14 and Somatostatin-25 on lipid metabolism in rainbow trout were evaluated by in vitro culture of liver and adipose tissue. The culture medium was subsequently analyzed for glycerol and fatty acid content and triacylglycerol lipase activity was measured within the tissues. Both Somatostatin-14 and Somatostatin-25 stimulated hepatic fatty acid and glycerol release within 3 h after treatment. Liver triacylglycerol lipase activity was elevated following treatment with Somatostatin-14 (76% above control) or Somatostatin-25 (94% above control). Somatostatin-14 and Somatostatin-25 also significantly stimulated the release of fatty acid and glycerol from adipose tissue. Triacylglycerol lipase activity in adipose tissue also was enhanced by both Somatostatins. These results indicate that Somatostatin-14 and Somatostatin-25 directly stimulate the mobilization of triacylglycerol from liver and adipose tissue, suggesting that these peptides are important systemic modulators of lipid metabolism in fish.
Hubert Vaudry - One of the best experts on this subject based on the ideXlab platform.
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Somatostatin down-regulates the expression and release of endozepines from cultured rat astrocytes via distinct receptor subtypes
Journal of Neurochemistry, 2005Co-Authors: Olfa Masmoudi, Hubert Vaudry, Pierrick Gandolfo, Tursonjan Tokay, Jérôme Leprince, Aurélia Ravni, Marie-christine TononAbstract:Endozepines, a family of regulatory peptides related to diazepam-binding inhibitor (DBI), are synthesized and released by astroglial cells. Because rat astrocytes express various subtypes of Somatostatin receptors (sst), we have investigated the effect of Somatostatin on DBI mRNA level and endozepine secretion in rat astrocytes in secondary culture. Somatostatin reduced in a concentration-dependent manner the level of DBI mRNA in cultured astrocytes. This inhibitory effect was mimicked by the selective sst4 receptor agonist L803-087 but not by the selective sst1, sst2 and sst3 receptor agonists L779-591, L779-976 and L797-778, respectively. Somatostatin was unable to further reduce DBI mRNA level in the presence of the MEK inhibitor U0126. Somatostatin and the sst1, sst2 and sst4 receptor agonists induced a concentration-dependent inhibition of endozepine release. Somatostatin and the sst1, sst2 and sst4 receptor agonists also inhibited cAMP formation dose-dependently. In addition, Somatostatin reduced forskolin-induced endozepine release. H89 mimicked the inhibitory effect of Somatostatin on endozepine secretion. In contrast the PLC inhibitor U73122, the PKC activator PMA and the PKC inhibitor calphostin C had no effect on Somatostatin-induced inhibition of endozepine release. The present data demonstrate that Somatostatin reduces DBI mRNA level mainly through activation of sst4 receptors negatively coupled to the MAPK pathway, and inhibits endozepine release through activation of sst1, sst2 and sst4 receptors negatively coupled to the adenylyl cyclase/PKA pathway.
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immunocytochemical localization of Somatostatin and autoradiographic distribution of Somatostatin binding sites in the brain of the african lungfish protopterus annectens
The Journal of Comparative Neurology, 1997Co-Authors: Mauro Vallarino, Maria Angela Masini, Michele Trabucchi, Nicolas Chartrel, Hubert VaudryAbstract:The anatomical distribution of Somatostatin-immunoreactive structures and the autoradiographic localization of Somatostatin binding sites were investigated in the brain of the African lungfish, Protopterus annectens. In general, there was a good correlation between the distribution of Somatostatin-immunoreactive elements and the location of Somatostatin binding sites in several areas of the brain, particularly in the anterior olfactory nucleus, the rostral part of the dorsal pallium, the medial subpallium, the anterior preoptic area, the tectum, and the tegmentum of the mesencephalon. However, mismatching was found in the mid-caudal dorsal pallium, the reticular formation, and the cerebellum, which contained moderate to high concentrations of binding sites and very low densities of immunoreactive fibers. In contrast, the caudal hypothalamus and the neural lobe of the pituitary exhibited low concentrations of binding sites and a high to moderate density of Somatostatin-immunoreactive fibers. The present results provide the first localization of Somatostatin in the brain of a dipnoan and the first anatomical distribution of Somatostatin binding sites in the brain of a fish. The location of Somatostatin-immunoreactive elements in the brain of P. annectens is consistent with that reported in anuran amphibians, suggesting that the general organization of the Somatostatin peptidergic systems occurred in a common ancestor of dipnoans and tetrapods. The anatomical distribution of Somatostatin-immunoreactive elements and Somatostatin binding sites suggests that Somatostatin acts as a hypophysiotropic neurohormone as well as a neurotransmitter and/or neuromodulator in the lungfish brain. J. Comp. Neurol. 388:337–353, 1997. © 1997 Wiley-Liss, Inc.
Maria Angela Masini - One of the best experts on this subject based on the ideXlab platform.
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Somatostatin in the ovary of an african lungfish protopterus annectens anin situhybridisation immunohistochemical and autoradiographical study
General and Comparative Endocrinology, 1999Co-Authors: Maria Angela Masini, Maddalena SturlaAbstract:Abstract In mammals, Somatostatin seems to be involved in the control of ovarian steroidogenesis. There have been no studies on the presence or actions of Somatostatin in the ovary of nonmammalian vertebrates. The localisation of Somatostatin-14 was examined immunohistochemically using the antibody to Somatostatin-14 in the ovary of the African lungfish Protopterus annectens. Immunoreactivity was present in the granulosa cells of mature ovarian follicle examined by light microscopy. Using an oligonucleotide probe complementary to mRNA for Somatostatin-14 and labelled at the 3′-end with α- 35 S, in situ hybridisation demonstrated Somatostatin-14 mRNA distributed in cells showing the same localisation as that of the immunoreactive cells. Binding sites for SST-14 were identified with autoradiography using [ 125 I]Somatostatin-14. Binding sites were localised on granulosa and theca cells. Somatostatin-14 may be thus synthesised in the lungfish ovary.
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immunocytochemical localization of Somatostatin and autoradiographic distribution of Somatostatin binding sites in the brain of the african lungfish protopterus annectens
The Journal of Comparative Neurology, 1997Co-Authors: Mauro Vallarino, Maria Angela Masini, Michele Trabucchi, Nicolas Chartrel, Hubert VaudryAbstract:The anatomical distribution of Somatostatin-immunoreactive structures and the autoradiographic localization of Somatostatin binding sites were investigated in the brain of the African lungfish, Protopterus annectens. In general, there was a good correlation between the distribution of Somatostatin-immunoreactive elements and the location of Somatostatin binding sites in several areas of the brain, particularly in the anterior olfactory nucleus, the rostral part of the dorsal pallium, the medial subpallium, the anterior preoptic area, the tectum, and the tegmentum of the mesencephalon. However, mismatching was found in the mid-caudal dorsal pallium, the reticular formation, and the cerebellum, which contained moderate to high concentrations of binding sites and very low densities of immunoreactive fibers. In contrast, the caudal hypothalamus and the neural lobe of the pituitary exhibited low concentrations of binding sites and a high to moderate density of Somatostatin-immunoreactive fibers. The present results provide the first localization of Somatostatin in the brain of a dipnoan and the first anatomical distribution of Somatostatin binding sites in the brain of a fish. The location of Somatostatin-immunoreactive elements in the brain of P. annectens is consistent with that reported in anuran amphibians, suggesting that the general organization of the Somatostatin peptidergic systems occurred in a common ancestor of dipnoans and tetrapods. The anatomical distribution of Somatostatin-immunoreactive elements and Somatostatin binding sites suggests that Somatostatin acts as a hypophysiotropic neurohormone as well as a neurotransmitter and/or neuromodulator in the lungfish brain. J. Comp. Neurol. 388:337–353, 1997. © 1997 Wiley-Liss, Inc.
C. D. Eilertson - One of the best experts on this subject based on the ideXlab platform.
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Effects of insulin, glucagon, and Somatostatin on the release of Somatostatin-25 and Somatostatin-14 from rainbow trout, Oncorhynchus mykiss, pancreatic islets in vitro.
General and comparative endocrinology, 1995Co-Authors: C. D. Eilertson, Jeffrey D. Kittilson, Mark A SheridanAbstract:Somatostatins are a diverse family of peptides known to modulate insulin and glucagon secretion as well as to stimulate glycogenolysis and lipolysis in salmonid fish. In this study, Brockmann bodies (bisected to yield hemi-islets) isolated from rainbow trout, Oncorhynchus mykiss, were used to study the effects of insulin, glucagon, and Somatostatin at various concentrations of glucose (1, 5, and 10 mM) on pancreatic Somatostatin release. The release of Somatostatin-25, the most predominate form of Somatostatin in salmonid pancreas, was stimulated by insulin in the presence of 1 and 5 mM glucose but not in the presence of 10 mM glucose, whereas glucagon stimulated Somatostatin-25 release only in the presence of high (10 mM) glucose. Somatostatin-25 release also was stimulated by Somatostatin-14. The secretion of Somatostatin-14 was suppressed by insulin in the presence of 5 and 10 mM glucose and was stimulated by glucagon in the presence of high (10 mM) glucose. These results indicate that insulin, glucagon, and Somatostatin-14 are regulators of Somatostatin-14 and Somatostatin-25 pancreatic release in rainbow trout and that these effects are modulated by glucose.
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Effects of Somatostatin-25 on lipid mobilization from rainbow trout, Oncorhynchus mykiss, liver and adipose tissue incubated in vitro. Comparison with Somatostatin-14
Journal of Comparative Physiology B-biochemical Systemic and Environmental Physiology, 1994Co-Authors: C. D. Eilertson, Mark A SheridanAbstract:The physiological effects of the pancreatic peptides Somatostatin-14 and Somatostatin-25 on lipid metabolism in rainbow trout were evaluated by in vitro culture of liver and adipose tissue. The culture medium was subsequently analyzed for glycerol and fatty acid content and triacylglycerol lipase activity was measured within the tissues. Both Somatostatin-14 and Somatostatin-25 stimulated hepatic fatty acid and glycerol release within 3 h after treatment. Liver triacylglycerol lipase activity was elevated following treatment with Somatostatin-14 (76% above control) or Somatostatin-25 (94% above control). Somatostatin-14 and Somatostatin-25 also significantly stimulated the release of fatty acid and glycerol from adipose tissue. Triacylglycerol lipase activity in adipose tissue also was enhanced by both Somatostatins. These results indicate that Somatostatin-14 and Somatostatin-25 directly stimulate the mobilization of triacylglycerol from liver and adipose tissue, suggesting that these peptides are important systemic modulators of lipid metabolism in fish.
Maddalena Sturla - One of the best experts on this subject based on the ideXlab platform.
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Somatostatin in the ovary of an african lungfish protopterus annectens anin situhybridisation immunohistochemical and autoradiographical study
General and Comparative Endocrinology, 1999Co-Authors: Maria Angela Masini, Maddalena SturlaAbstract:Abstract In mammals, Somatostatin seems to be involved in the control of ovarian steroidogenesis. There have been no studies on the presence or actions of Somatostatin in the ovary of nonmammalian vertebrates. The localisation of Somatostatin-14 was examined immunohistochemically using the antibody to Somatostatin-14 in the ovary of the African lungfish Protopterus annectens. Immunoreactivity was present in the granulosa cells of mature ovarian follicle examined by light microscopy. Using an oligonucleotide probe complementary to mRNA for Somatostatin-14 and labelled at the 3′-end with α- 35 S, in situ hybridisation demonstrated Somatostatin-14 mRNA distributed in cells showing the same localisation as that of the immunoreactive cells. Binding sites for SST-14 were identified with autoradiography using [ 125 I]Somatostatin-14. Binding sites were localised on granulosa and theca cells. Somatostatin-14 may be thus synthesised in the lungfish ovary.
