Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P61278 (somatostatin)
 22,083 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of a sulfonylurea, glibenclamide, on the release of insulin, glucagon, and somatostatin was studied in the isolated perfused rat pancreas. At glucose concentrations of 1.1 mM or less, the drug stimulated somatostatin release, whereas glucagon release, after 2-3 min of increase, was markedly inhibited. Insulin release was moderately stimulated, and maximal release occurred relatively late. A moderate glucose load (6.7 mM) inhibited glibenclamide-induced release of somatostatin, whereas the two in combination exerted an additive action on insulin release. Greater glucose loads, which by themselves would stimulate somatostatin release, only marginally suppressed glibenclamide-induced somatostatin release. The insulinogenic effect of these glucose levels was not modified by glibenclamide. Glibenclamide may thus stimulate both the alpha and beta as well as delta cells of the pancreas, depending on glucose concentration. We suggest a paracrine (local) interaction of somatostatin with the alpha and beta cells, which has an important role in the kinetics of insulin and glucagon release induced by sulfonylureas.
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PMID:Effect of glucose/sulfonylurea interaction on release of insulin, glucagon, and somatostatin from isolated perfused rat pancreas. 11 58

The sulfonylurea glibenclamide, which is known to block ATP-sensitive potassium channels, increases, in a dose-dependent manner, the release of PRL from MMQ pituitary cells. Glibenclamide does not reduce the dopaminergic inhibition of forskolin-stimulated PRL secretion; conversely it almost completely abolishes the inhibitory effect of somatostatin (SRIF) on this parameter. The sulfonylurea dose dependently increases basal [Ca++]i, without affecting the increase in [Ca++]i induced by high concentrations of extracellular potassium. Glibenclamide does not modify dopamine-induced [Ca++]i reduction, whereas it abolishes the inhibitory effect of SRIF on basal [Ca++]i. In the presence of diazoxide, an opener of ATP-sensitive potassium channels, which lowers basal [Ca++]i, dopamine still reduces [Ca++]i whereas SRIF does not induce a further decrease. Glibenclamide induces the depolarization of the cell membrane and prevents the SRIF-evoked hyperpolarization. The hyperpolarization of the cell membrane induced by dopamine is not modified by glibenclamide. Diazoxide induces a cell membrane hyperpolarization that is enhanced by dopamine but not by SRIF. Finally, glibenclamide does not affect basal and stimulated adenylate cyclase activity. In conclusion, our findings show that, in MMQ cells, glibenclamide stimulates PRL release, suggesting an involvement of ATP-sensitive potassium channels in the regulation of PRL secretion. The reversal by glibenclamide of the effects of SRIF on calcium homeostasis, membrane potential, and PRL release suggests that this type of potassium channel participates to the somatostatinergic inhibition of PRL secretion. Conversely, we found that glibenclamide does not modify the dopaminergic inhibition of PRL secretion and second messenger systems, suggesting that ATP-sensitive potassium channels may not be involved in the inhibitory effect of dopamine on PRL release.
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PMID:Dopamine and somatostatin inhibition of prolactin secretion from MMQ pituitary cells: role of adenosine triphosphate-sensitive potassium channels. 135 54

We previously reported that sulfonylurea treatment reduces insulin (IRI), glucagon (IRG) and somatostatin (SRIF) release following metabolic stimuli from the isolated perfused pancreas of normal rats and that a reduction in IRI, IRG and SRIF pancreatic content was also observed. The present work was undertaken to investigate the effects of long-term glibenclamide treatment on the gastrointestinal content of gut hormones in normal rats. Moreover, the effects of sulfonylurea treatment on IRI, IRG, and SRIF pancreatic content were also analyzed and compared to the peripheral hormone plasma levels. Two groups of male Sprague-Dawley rats received glibenclamide (1 mg/kg/day per os; n = 14) or placebo (distilled water; n = 10) for 5 months, respectively. Tissue contents of IRI, IRG and SRIF in acid-ethanol extracts of pancreas and of gastric inhibitory peptide (GIP), vasoactive intestinal polypeptide (VIP), entero-glucagon (gut-GLI) and SRIF in acid-ethanol extracts of intestine were determined. Blood glucose and plasma pancreatic hormone levels were also measured. Glibenclamide treatment lowered the levels of IRI, IRG and SRIF in the pancreatic tissue; in the same way gut-GLI, SRIF and VIP intestinal concentrations were significantly reduced, whereas no significant inhibition was detected in intestinal GIP content. Blood glucose levels and IRI and SRIF plasma concentrations were similar in the two groups. IRG plasma levels were reduced in the sulfonylurea group. These findings might suggest that sulfonylurea suppresses hormone biosynthesis in a non-specific manner.
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PMID:Effects of long-term glibenclamide administration on gastrointestinal and pancreatic hormones in normal fasting rats. 249 27

The actions of somatostatin and of the phorbol ester 4 beta-phorbol 12-myristate 13-acetate (PMA) were studied in rat insulinoma (RINm5F) cells by electrophysiological and 86Rb+ flux techniques. Both PMA and somatostatin hyperpolarize insulinoma cells by activating ATP-sensitive K+ channels. The presence of intracellular GTP is required for the somatostatin effects. PMA- and somatostatin-induced hyperpolarization and channel activity are inhibited by the sulfonylurea glibenclamide. Glibenclamide-sensitive 86Rb+ efflux from insulinoma cells is stimulated by somatostatin in a dose-dependent manner (half maximal effect at 0.7 nM) and abolished by pertussis toxin pretreatment. Mutual roles of a GTP-binding protein, of protein kinase C, and of cAMP in the regulation of ATP-sensitive K+ channels are discussed.
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PMID:Regulation of ATP-sensitive K+ channels in insulinoma cells: activation by somatostatin and protein kinase C and the role of cAMP. 256 41

We have attempted to define the effect of glucose, glyburide, and isobutylmethylxanthine (IBMX) upon secretion vesicle margination to the plasma membrane and granule lysis. Margination of secretion vesicles during exocytosis was assessed by measuring the recruitment of somatostatin (SRIF) receptors. Secretion vesicle lysis was studied by measuring insulin release into the incubation media. Our observations suggest that glucose directly affects both secretion vesicle margination and lysis. Both events are rapidly influenced by this secretagogue (within 10 min of incubation). Trifluoperazine (TFP) and removal of Ca2+ from the incubation media significantly reduced glucose-induced margination of secretion vesicles and their lysis (P less than 0.001). IBMX primarily influences the lysis of secretion vesicles and not their margination. IBMX caused a rapid increase in insulin secretion within 10 min without recruitment of SRIF receptors. Neither TFP nor the absence of extracellular Ca2+ affected IBMX-induced insulin release. Late enhancement in margination of secretion vesicles (30 min of incubation with IBMX) is probably related to the initial event of secretion vesicle lysis and is independent of extracellular calcium. Glyburide exerts its action in a manner similar to glucose, affecting both the lysis of secretion vesicles and their margination. However, the action of glyburide is independent of extracellular calcium and partially dependent upon calmodulin.
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PMID:Control of secretion vesicle margination and lysis by glucose, IBMX, and glyburide. 257 75

In 20 patients with non-insulin-dependent diabetes mellitus (NIDDM) and secondary failure to sulfonylurea, a double-blind randomized study was performed comparing two regimes: insulin plus placebo (IP) and insulin plus glyburide (IG). The protocol included two hospitalization periods (days 1-18 and 78-85) and follow-up at the outpatient clinic for 325 days. The metabolic control was kept as tight as possible. The subjects underwent normoglycemic clamp studies and meal tests with determination of insulin, C-peptide, glucagon, somatostatin, and gastric inhibitory polypeptide in plasma. On IG, they demonstrated marked and long-lasting improvement of metabolic control: HbA1c decreased from 11.1 +/- 0.3% on day 3 to 8.3 +/- 0.4% (P less than .001) on day 78 and 9.1 +/- 0.5% (P less than .001) on day 325. In subjects on IP, the corresponding values were 10.3 +/- 0.5, 8.4 +/- 0.4 (P less than .001), and 8.9 +/- 0.5% (P less than .05). Body weight increased by 6.0 +/- 1.5 kg (P less than .005) on IG and 2.9 +/- 2.1 kg (NS) on IP. The daily insulin requirement decreased on IG from 62.5 +/- 12.9 U/day on day 7 to 33.5 +/- 8.8 U/day on day 83 and 34.6 +/- 8.9 U/day on day 325. On IP the insulin requirement was almost constant: 62.0 +/- 10.7 U/day on day 7, 55.5 +/- 7.7 U/day on day 83, and 54.7 +/- 7.9 U/day on day 325. Insulin sensitivity measured with the hyperinsulinemic clamp (plasma insulin approximately equal to 130 microU/ml) was similar on IP and IG at the initiation of the study and was unchanged on days 18 and 85. A key observation of this study, although the mechanism is unclear, is that isoglycemic-meal-related insulin requirement was diminished by insulin treatment, indicating improvement of meal-related insulin sensitivity. Glyburide increased basal and meal-but not glucagon-stimulated insulin and C-peptide levels, and also augmented the effect of meals on somatostatin release. We conclude that in NIDDM, IG regime promptly and continuously decreased insulin requirement and improved metabolic control. This effect is, at least during the first 3 mo, mainly due to enhanced insulin secretion. IG and IP treatment had no effect on insulin sensitivity during hyperinsulinemic-normoglycemic clamp, whereas meal-related insulin sensitivity was augmented.
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PMID:Glyburide decreases insulin requirement, increases beta-cell response to mixed meal, and does not affect insulin sensitivity: effects of short- and long-term combined treatment in secondary failure to sulfonylurea. 289 May 1

The involvement of K+ channels in regulating secretion of amylase from isolated rat parotid acini was studied in conjunction with beta-adrenoceptor function. It was observed that increasing the concentration of extracellular K- or adding K+ channel blockers enhanced the secretion of amylase. Among several K+ channel blockers, tetraethylammonium, apamin and charybdotoxin were effective to enhance secretion by 48, 69 and 84%, respectively. Glibenclamide was without effect. A low concentration of isoprenaline (10(-7) M) enhanced secretion by 154% and its simultaneous application with tetraethylammonium gave a synergistic effect, producing 371% stimulation. Combination of tetraethylammonium and a low concentration of carbachol (10(-6) M) did not give the synergistic effect. Isoprenaline at the concentration of 10(-6) M enhanced secretion by 313% and this was reduced to 116% by 10(-5) M valinomycin, a K+ ionophore. Valinomycin was without effect on carbachol (10(-5) M)-induced secretion. Somatostatin (10(-5) M) and morphine (10(-4) M) also reduced isoprenaline-induced secretion of amylase. These results suggested the regulation of Ca(2+)-activated K+ channels by isoprenaline in amylase secretory processes in parotid acini.
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PMID:Effects of K+ channel blockers and K+ ionophore on isoprenaline-induced secretion of amylase from rat parotid acini. 908 65