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 role of endogenous prostaglandins in the physiologic regulation of gastric secretion is unclear. We evaluated the effect of indomethacin, an inhibitor of endogenous prostaglandin synthesis, on basal gastric secretion in humans using a two-component model for calculating gastric acid and bicarbonate secretion. After a control, gastric secretory study, 11 healthy volunteers were given 50 mg of indomethacin orally every 8 h for a total of 10 doses, after which the gastric secretory experiment was repeated. Indomethacin significantly (p less than 0.05) increased basal gastric juice volume, hydrogen ion concentration, osmolality, and acid output. Indomethacin increased acid secretion significantly (from 4.9 +/- 1.2 to 7.4 +/- 1.7 mmol/75 min, p less than 0.02) without affecting gastric bicarbonate secretion (control 2.7 +/- 0.8, indomethacin 3.0 +/- 0.7 mmol/75 min; p greater than 0.05). The increase in basal acid secretion after indomethacin administration was quite variable from subject to subject and was unaccompanied by significant changes in basal serum gastrin concentrations. Unlike basal acid secretion, indomethacin had no significant effect on acid secretion stimulated by intragastric infusion of homogenized food. Moreover, indomethacin did not prevent intravenous somatostatin 14 from inhibiting food-stimulated acid secretion, in contrast to a previous study in rats in which indomethacin blocked the inhibitory effect of somatostatin on acid secretion. Assuming the effect of indomethacin is due to reduced endogenous prostaglandin synthesis, we conclude that (a) in some individuals endogenous prostaglandins suppress basal acid secretion by a mechanism independent of the hormone gastrin; (b) endogenous prostaglandins play little, if any, role in the regulation of basal bicarbonate secretion by the stomach; and (c) endogenous prostaglandins do not regulate food-stimulated acid secretion, nor do they mediate the inhibitory effect of somatostatin on gastric acid secretion in humans.
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PMID:Effect of indomethacin on gastric acid and bicarbonate secretion in humans. 614 64

The influence of substance P (SP) and somatostatin (SS) on contractions induced by electrical field stimulation, ATP and carbachol were investigated in isolated rabbit urinary bladder. Some experiments were also carried out in rat and guinea-pig detrusor. When added cumulatively to rabbit and rat preparations, SP and SS caused a gradual increase in tone of the preparations. There were no effects on the electrically induced contractions. In rabbit and rat detrusor pretreated with guanethidine, atropine and indomethacin, the contractile response to nerve stimulation was markedly reduced. In this situation SP and SS caused 2-4 fold increase in the electrically induced contractions. Indomethacin abolished the tonic response to ATP in the rabbit detrusor, and reduced the initial phasic contraction by about 30%. Both SP and SS were able to restore the phasic contraction to the level obtained before indomethacin addition. The contractions induced by carbachol in rabbit and rat detrusor were not affected by SP and SS, not even in indomethacin pretreated preparations. The SP-antagonist (D-Pro2, D-Phe, D-Trp9)-SP was tested in isolated rabbit, rat, and guinea-pig detrusor. Concentrations of the antagonist which effectively inhibited contractions induced by a submaximum concentration of SP had no effect on the contractile response to electrical field stimulation in rabbit and guinea-pig preparations, and rather tended to increase the contractions in the rat detrusor. The results suggest that neither SS nor SP is the mediator of excitatory non-cholinergic, non-adrenergic activation of rabbit urinary bladder. A role as local modulators of neuromuscular transmission cannot be excluded.
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PMID:Substance P and somatostatin and excitatory neurotransmission in rabbit urinary bladder. 617 Dec 17

In isolated detrusor from guinea-pigs and rats substance P (SP) induced concentration-dependent phasic contractions. Rabbit detrusor strips responded to SP with an initial phasic and an ensuing tonic contraction. The concentration-response curve to SP in this preparation had a biphasic appearance. Eledoisin (E) caused contractile responses similar to those of SP when tested on the guinea-pig detrusor. Somatostatin was tested on the rabbit urinary bladder; it caused a concentration-dependent rise in basal tone, but no phasic contraction. The responses to SP and E were not affected by tetrodotoxin or physostigmine. They were only partly inhibited by high concentrations of atropine and the anticholinergic drug PR 197. Noradrenaline and isoprenaline caused a concentration-dependent inhibition of the peptide induced responses in guinea-pig bladder; at high concentrations in the amines this inhibition was almost complete. Indomethacin did not affect the SP induced contractions in the guinea-pig bladder, reduced the responses in the rabbit detrusor, but increased them in the rat bladder. Contractions elicited by SP and E were rapidly diminished or abolished after 30 min. treatment in a calcium-free medium. The responses were also inhibited by the calcium antagonist nifedipine. In guinea-pig preparations depolarized by potassium (127 mM) both SP and E caused a contractile response approximately 20% of that obtained in normal Tyrode solution. It is concluded that SP and E cause contraction of detrusor by a direct effect on the smooth muscle cells, and that this response is dependent on the extracellular calcium concentration. Prostaglandins may be involved in the SP-induced response of the rabbit detrusor.
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PMID:Contractile effects of some polypeptides on the isolated urinary bladder of guinea-pig, rabbit, and rat. 617 55

Continuously superfused rat anterior pituitary cells were used to study the effects of prostaglandins (PGs) and a thromboxane (TX) on the secretion of TSH. Indomethacin, a blocker of PG synthetase, inhibited the amount of TSH secreted in response to TRH. This reduction in TRH responsiveness was overcome by administration of PGE2 in combination with the TRH. Arachidonic acid, a prostanoid precursor, increased the amount of TSH released by TRH. Superfusion with TXB2 or imadazole, an inhibitor of TX synthetase, did not change TSH secretion. PGs A2, B2, D2, F1 alpha, F2 alpha, and endoperoxide analogs U-44069 and U-46619 had no effect on hormone release. PGE1 and E2 both increased TRH-stimulated TSH, but neither compound affected basal output; PGI2 was found to stimulate TSH release. Somatostatin inhibited TRH-induced TSH, but failed to block the effects of the PGs. These studies demonstrate that PGs, but no TXs, play a role in TSH secretion. PGE1 and PGE2 appear to modulate TRH responsiveness, while PGI2 directly stimulates hormone output.
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PMID:Effects of various prostanoids on thyrotropin secretion by superfused anterior pituitary cells. 678 40

Adult onset Fanconi syndrome with medullary cystic kidney was diagnosed in a 30-year-old male with muscular weakness, hypokalemia, normal BP, hyperreninemia, and secondary aldosteronism. He also had non-specific aminoaciduria, lysozymuria, and beta 2-microglobulinuria. Urinary concentrating and acidifying capacity was impaired, and both sodium and potassium were lost into the urine. I.v. pyelography revealed medullary cystic kidney. Renal biopsy showed juxtaglomerular hyperplasia, heavy subintimal deposits and C3 and IgG in preglomerular arteriolar walls, and degenerative changes in the tubules, including loss of brush border and "macula densa-like" lesions. Polycythemia with elevated serum erythropoietin levels, and raised blood ACTH values with features of cortisolism were also present. Indomethacin therapy decreased plasma renin activity (PRA), plasma aldosterone, and urinary loss of potassium and sodium, while serum potassium approached normal levels. Metoprolol, a beta-adrenergic blocking agent, caused similar effects. Insensitivity to the pressor effect of angiotensin II was reversed by indomethacin treatment. Somatostatin infusion lowered PRA and aldosterone without affecting BP. Several biochemical aberrations of this patient resemble Bartter's syndrome, including the effect of indomethacin.
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PMID:Hyperreninemia, lysozymuria, and erythrocytosis in Fanconi syndrome with medullary cystic kidney. 699 16

Evidence in vivo indicates that endogenous and exogenous prostaglandins can alter gastrin secretion. We have used primary cultures containing canine antral G-cells to study the cellular actions of prostaglandins on gastrin secretion, comparing the effects of prostaglandin E2 (PGE2) and its synthetic analogue enprostil. Enprostil (10(-10)-10(-6) M) inhibited gastrin secretion in response to bombesin, carbachol, and forskolin, the latter a receptor-independent activator of adenylate cyclase. This inhibition by enprostil was reversed by treatment with pertussis toxin (200 ng/ml, 8 h). However, enprostil did not inhibit the postreceptor stimuli 8-bromoadenosine 3',5'-cyclic monophosphate (10(-3) M), calcium ionophore A-23187 (10(-7) M), or 4 beta-phorbol 12-myristate 13-acetate (10(-8) M). In contrast, whereas PGE2 inhibited forskolin-stimulated gastrin release, PGE2 did not inhibit the response to carbachol or bombesin in control cultures. However, in pertussis toxin-treated cultures, PGE2 inhibition was reversed and, in contrast, the responses to bombesin, carbachol, and possibly forskolin were augmented. Indomethacin at a dose of 10(-5) M did not alter basal or bombesin-stimulated gastrin secretion. However, the somatostatin antibody CURE-S6 enhanced the response to forskolin and enhanced inhibition by PGE2, suggesting that endogenous somatostatin produced an inhibitory tone in these cultures and excluding the possibility that PGE2 acted via release of endogenous somatostatin. Our data suggest that in cultured antral cells gastrin release is regulated by inhibitory and stimulatory prostaglandin mechanisms.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of prostaglandins on gastrin release from canine antral mucosal cells in primary culture. 814 Dec 91

1. Secretin has been recognized as an important enterogastrone. In order to investigate the mechanism of secretin-induced inhibition of gastric acid secretion, the effects of both anti-somatostatin antibody and indomethacin on acid secretion were examined in conscious rats with gastric cannulas. 2. Secretin given intravenously at 5.6 pmol kg-1 h-1 inhibited profoundly the acid secretion stimulated by pentagastrin at 0.3 microgram kg-1 h-1. 3. When a rabbit antisomatostatin serum was given intravenously, it not only abolished the secretin-induced inhibition on the pentagastrin-stimulated acid secretion, but also augmented both basal and pentagastrin-stimulated acid secretion. 4. Indomethacin also significantly augmented basal acid secretion, starting 45 min after the drug delivery began. It reversed the secretin-induced inhibition but it did not augment the pentagastrin-stimulated acid secretion. 5. Neither antisomatostatin serum influenced prostaglandin E2-induced inhibition of the pentagastrin-stimulated acid secretion, nor did indomethacin affect the inhibition by somatostatin, suggesting strongly that the inhibition by somatostatin is not mediated by endogenous prostaglandins, nor is that by prostaglandins E2 mediated by endogenous somatostatin. 6. It is concluded that the inhibitory action of secretin on pentagastrin-stimulated gastric acid secretion is mediated by both somatostatin and prostaglandins in conscious rats. The two inhibitors do not seem to interact endogenously for the inhibition of acid secretion. While endogenous somatostatin exerts a tonic inhibitory effect on both basal and pentagastrin-simulated acid secretion, prostaglandins augment basal acid secretion only.
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PMID:The mechanism of inhibitory action of secretin on gastric acid secretion in conscious rats. 856 88

This study investigates the neural pathways, mediators, and cyclooxygenase isoenzymes involved in the gastroprotection conferred by peptone in rats. Intragastric perfusion with 8% peptone protected against gross and histological damage induced by subsequent perfusion with 50% ethanol. The gastroprotective effect of peptone was near maximally inhibited by gastrin immunoneutralization, inactivation of capsaicin-sensitive afferent neurons, calcitonin gene-related peptide (CGRP) immunoneutralization, blockade of gastrin receptors, CGRP, bombesin/gastrin-releasing peptide (GRP), or somatostatin receptors, and by the nitric oxide (NO) synthase inhibitor NG-nitro-L-arginine methyl ester and was partially (46%) counteracted by atropine. Indomethacin and the selective cyclooxygenase-2 inhibitors NS-398 and L-745,337 dose dependently (50% inhibitory dose, 4.2, 0.8, and 1.5 mg/kg, respectively) attenuated the peptone-induced protection. Dexamethasone was ineffective. These results indicate that protective effects of peptone involve endogenous gastrin and possibly somatostatin and are mediated by capsaicin-sensitive afferent, cholinergic, and bombesin/GRP neurons. CGRP, NO, and prostaglandins participate as essential mediators. The study provides evidence that prostaglandins derived from a constitutive cyclooxygenase-2 contribute to mucosal defense in the presence of ulcerogens and thus participate in homeostatic functions of the stomach.
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PMID:Peptidergic and cholinergic neurons and mediators in peptone-induced gastroprotection: role of cyclooxygenase-2. 961 78

Duodenal fat such as oleate is known to influence gut functions by release of cholecystokinin (CCK), but the contribution of CCK endogenously released by duodenal fat or by diversion of pancreatic juice from the duodenum in the mechanism of mucosal integrity and gastroprotection has been little studied. This study was designed to compare the effect of CCK-8 and intraduodenal (i.d.) instillation of sodium oleate, or diversion of the pancreatic biliary secretions that are known to release CCK, on the gastric mucosal lesions induced by topical application of 100% ethanol or acidified aspirin (ASA) in rats with or without the pretreatment with a CCK-A receptor antagonist, loxiglumide, or with L-365,260 to block CCK-B receptors. In addition, the effect of suppression of prostaglandin (PG) biosynthesis by indomethacin (5 mg/kg i.p.), inhibition of nitric oxide (NO)-synthase by L-NAME (5 mg/kg i.v.), or blockade of sensory nerves by capsaicin (125 mg/kg s.c.) on the protective activity of sodium oleate was determined. Sodium oleate (50-200 mM i.d.), or diversion of pancreatic juice from the duodenum for 3 h that produced significant rise in plasma CCK levels, significantly reduced gastric lesions induced by 100% ethanol to an extent similar to that induced by exogenous CCK-8 (5 nmol/kg s.c.). The protective effect of oleate or diversion of pancreatic juice was accompanied by an increase in gastric blood flow (GBF). Both protection and accompanying hyperemia were completely abolished by blockade of CCK-A receptors with loxiglumide, whereas L-365,260, an antagonist of CCK-B receptors, had no effect. Oleate given i.d. significantly attenuated acidified ASA-induced gastric lesions and gastric secretion while increasing the luminal concentration of somatostatin. These effects were significantly reduced by loxiglumide but not by L-365,260. In contrast, CCK-8, which stimulated gastric acid secretion, failed to affect the lesions induced by acidified ASA and the decrease in the GBF produced by this ulcerogen. Indomethacin, which suppressed PG generation by approximately 90%, failed to influence the protective activity of oleate or CCK-8 against ethanol-induced lesions, whereas L-NAME, vagotomy, or sensory denervation significantly attenuated this protection and accompanying hyperemia. Addition to L-NAME of L-arginine, but not D-arginine, restored the protective and hyperemic effects of CCK-8 and duodenal oleate against gastric lesions induced by ethanol or acidified ASA. We conclude that endogenous CCK released by oleate or diversion of pancreatic secretion exerts a potent gastroprotective action on the stomach involving predominantly CCK-A receptors and depending on vagal activity, and hyperemia mediated by NO and sensory nerves but unrelated to acid secretory effects and endogenous PG.
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PMID:Involvement of endogenous cholecystokinin and somatostatin in gastroprotection induced by intraduodenal fat. 987 9


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