Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01350 (gastrin)
 9,683 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

There is convincing evidence from in vitro studies that prostaglandins interfere with the gastrin histamine regulation of gastric acid secretion in an opposing manner. They can inhibit the action of histamine on the parietal cell when given as single-dose treatment. Conversely, when given at high doses, they liberate endogenous histamine, probably from nonparietal cells. In in vivo experiments prostaglandins are potent inhibitors of acid secretion when studied with single-dose treatment but are capable of stimulating basal acid secretion when chronically applied to rats. Studies performed in whole animal preparations on the effect of cyclooxygenase inhibitors have not fully clarified which of these two histamine-modulating effects of prostaglandins is of prime physiologic significance but favour suppression of histamine activity with subsequent acid inhibition. It appears that somatostatin release is the mechanism through which prostaglandin can simultaneously inhibit acid secretion and release plasma gastrin. At least in the rat, the pattern of plasma gastrin and somatostatin release is, similarly to acid secretion, partly reversed during prolonged prostaglandin treatment.
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PMID:Aspects of the role of prostaglandins in gastrin histamine regulation of gastric acid secretion. 167 23

The effects of cyclooxygenase inhibition by indomethacin on gastric acid secretion were studied in 8 healthy men. Oral doses of indomethacin (200 mg), administered 15 and 2 h before testing, were known to inhibit prostaglandin synthesis by 90% in 3 of the subjects as determined by prostaglandin E2 generation assay on endoscopically obtained gastric mucosal biopsy specimens. Acid-induced inhibition of gastric acid secretion was evaluated in a randomized and blinded study in which acid output was measured for 2 h during basal conditions by aspiration, for the next 2 h by intragastric titration during distention with isotonic glucose, and for the following 2 h by intragastric titration during meal stimulation with peptone. The studies were done on separate days, and intragastric pH was maintained at either 2.5 or 5.5 after administration of indomethacin or placebo. Basal acid output was not altered by indomethacin treatment. Distention of the stomach stimulated acid output significantly to a similar degree in all groups, without affecting plasma gastrin. Meal stimulation increased plasma gastrin and acid output significantly more at pH 5.5 (47 +/- 12 pM, 13 +/- 2 mmol/30 min) than at pH 2.5 (30 +/- 8 pM, 6 +/- 2 mmol/30 min). No effect of indomethacin treatment was observed. It is concluded that the participation of cyclooxygenase products in the mechanisms by which acid inhibits the gastric phase of acid secretion in humans is likely to be minor. These results also cast doubt on an important physiologic role for cyclooxygenase products in the regulation of basal acid secretion or of acid secretion stimulated by distention or a peptone meal.
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PMID:Gastric acidification inhibits meal-stimulated gastric acid secretion after prostaglandin synthesis inhibition by indomethacin in humans. 310 64

The effect of cyclooxygenase inhibition by indomethacin on the mechanism by which fat inhibits gastric acid secretion was studied in eight healthy men. Oral 200-mg doses of indomethacin administered 15 h and 2 h before testing is known to inhibit prostaglandin synthesis by 90%, as determined by prostaglandin E2 generation assay on endoscopically obtained gastric mucosal biopsy specimens. Fat-induced inhibition of gastric acid secretion was evaluated by intragastric administration of 200 ml vegetable oil or glucose (control) for 30 min, followed by intragastric titration with peptone at pH 5.5 for 2 h. The mean acid output was significantly lower after fat (8 +/- 0.2 mmol 30 min-1) as compared with control (12 +/- 0.5 mmol 30 min-1). The fat-induced inhibition was unaffected by indomethacin treatment, and the plasma gastrin responses were similar in all groups. It is concluded that the participation of cyclooxygenase products such as prostaglandins in the mechanisms by which fat inhibits the gastric phase of acid secretion in man is likely to be minor.
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PMID:Fat inhibits meal-stimulated gastric acid secretion after prostaglandin synthesis inhibition by indomethacin in man. 311 61

The effects of a stable prostaglandin (PG) E2 analog (15-R-15 methyl PGE2) and aspirin, a potent inhibitor of cyclooxygenase, on modified sham-feeding (MSF)-stimulated gastric secretion and serum gastrin and pancreatic polypeptide (PP) levels were measured in patients with duodenal ulcer. PGE2 analog given orally significantly reduced gastric acid and pepsin secretion and suppressed serum PP but not gastrin responses to MSF. Suppression of PG generation in the gastric mucosa did not influence the secretory or hormonal responses to MSF. This study shows that endogenous PGs are not involved in the control of vagally stimulated gastric secretion, but exogenous PGE2 analog is an effective inhibitor of such secretion and merits clinical evaluation in the treatment of duodenal ulcer.
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PMID:Prostaglandins and vagal stimulation of gastric secretion in duodenal ulcer patients. 642 38

Epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), and insulin all dose-dependently stimulated [3H]-thymidine incorporation into guinea pig gastric mucous cells cultured in vitro. On the other hand, other growth factors, e.g., platelet-derived growth factor (PDGF) and gastrointestinal hormones, such as gastrin, had no effect on DNA synthesis in these cells. Exposure of the cells to EGF at concentrations which stimulated DNA synthesis caused increases in both prostaglandin (PG) E2 release and cyclooxygenase (COX) enzyme protein synthesis, as evaluated by Western blot analysis. These results suggest that such increases in DNA synthesis and PGE2 release may be involved, at least in part, in the mechanism of EGF-induced local regulation of gastric mucosal integrity.
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PMID:EGF stimulates both cyclooxygenase activity and cell proliferation of cultured guinea pig gastric mucous cells. 792 Nov 58

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

Ulcer healing involves expression of various growth factors including hepatocyte growth factor (HGF) at the ulcer margin and the rise in plasma gastrin but the effects of locally applied HGF and gastrin, which are known to act as trophic factors for the gastric mucosa, with or without neutralizing antibodies against HGF and gastrin or COX-1 and COX-2 inhibitors on ulcer healing and the expression of cyclooxygenase (COX)-1 and COX-2 during this healing have been little studied. Rats with gastric ulcers induced by serosal application of acetic acid (ulcer area 28 mm2) received a submucosal injection of either: 1)vehicle (saline), 2) HGF and 3) gastrin with or without neutralizing antibodies against HGF and gastrin or treatment with indomethacin (2 mg/kg-d i.p.), a non-specific inhibitor of COX, or NS-398 (5 mg/kg-d i.g.) and Vioxx (10 mg/kg-d i.g.), both highly specific COX-2 inhibitors. Each growth factor and specific antibodies against HGF and gastrin (100 ng/100 microl each) were injected just around the ulcer immediately after ulcer induction and this local application was repeated at day 2 following anesthesia and laparotomy. At day 13 and 21, the area of ulcers was determined by planimetry, the gastric blood flow (GBF) at ulcer margin was examined by H2-gas clearance technique and mucosal generation of PGE2 and the expression of COX-1 and COX-2 mRNA in the non-ulcerated and ulcerated gastric mucosa was analyzed using RT-PCR. The gastric ulcers healed progressively within 21 days and this effect was accompanied by significant increase in the GBF at the ulcer margin and expression of COX-2 mRNA and COX-2 protein at the ulcer area. Treatment with HGF and gastrin significantly accelerated the rate of ulcer healing and raised GBF at ulcer margin causing further significant upregulation of COX-2 mRNA and COX-2 protein (but not of COX-1 mRNA ) in the ulcerated mucosa. The upregulation of COX-2 mRNA induced by HGF was significantly attenuated by the concurrent local treatment with antibody against this growth peptide. Indomethacin and both COX-2 inhibitors significantly prolonged the ulcer healing, while suppressing the generation of PGE2 in non-ulcerated and ulcerated gastric mucosa and the GBF at ulcer margin. The acceleration of ulcer healing by HGF and gastrin and accompanying rise in the GBF at ulcer margin were significantly attenuated by the concurrent treatment with indomethacin or NS-398 and Vioxx. HGF injections produced a significant rise in the plasma gastrin levels and this was significantly attenuated by the cotreatment with NS-398. We conclude that 1) neutralization of HGF and gastrin by their specificantibodies delays ulcer healing due fall in the microcirculation around the ulcer and a decrease in the COX-2 expression, 2) COX-2 derived prostaglandins may play an important role in acceleration of the ulcer healing by various growth factors including HGF and gastrin, 3) enhancement of the local pool for growth factors such as HGF and gastrin at the ulcer site could offer a new modality for treatment of gastric ulcer.
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PMID:Involvement of cyclooxygenase (COX)-2 products in acceleration of ulcer healing by gastrin and hepatocyte growth factor. 1119 47

The ECL cells control parietal cells by releasing histamine in their immediate vicinity. Gastrin and pituitary adenylate cyclase-activating peptide (PACAP) stimulate histamine secretion from isolated ECL cells, while somatostatin and galanin inhibit stimulated secretion. Prostaglandin E2 and related prostaglandins likewise suppress ECL-cell histamine secretion. Conceivably, that is how they inhibit acid secretion. In the present study, we examined if prostaglandin E2 can be generated by isolated ECL cells. Rat stomach ECL cells were purified (>90% purity) by counterflow elutriation and gradient centrifugation and cultured for 48 h. ECL cell stimulants (gastrin and PACAP) and inflammatory agents (interleukin-1 beta, tumor necrosis factor-alpha and bradykinin) were tested for their ability to induce prostaglandin E2 accumulation (24-h incubation), measured by radioimmunoassay. Gastrin and PACAP did not affect prostaglandin E2 accumulation but interleukin-1 beta (300 pg/ml), tumor necrosis factor-alpha (10 ng/ml) and bradykinin (1 microM) induced a 2- to 3-fold increase in the amount of prostaglandin E2 accumulated. While the combination of interleukin-1 beta and bradykinin induced a 9-fold increase, the combination interleukin-1 beta+tumor necrosis factor-alpha and bradykinin + tumor necrosis factor-alpha induced additive effects only. The combination of interleukin-1 beta + tumor necrosis factor-alpha + bradykinin did not induce a greater effect than interleukin-1 beta + bradykinin. The effect of interleukin-1 beta + bradykinin was abolished by adding 10 nM hydrocortisone (suppressing phospholipase A2 and cyclooxygenase) or 1 microM indomethacin (inhibiting cyclooxygenase). Incubating ECL cells in the presence of interleukin-1 beta+bradykinin for 24 h reduced their ability to secrete histamine in response to gastrin. The inhibitory effect was reversed by 1 microM indomethacin. Also, increasing the concentrations of hydrocortisone in the medium resulted in an enhanced gastrin-stimulated histamine secretion. Hence, the previously described acid-inhibiting effect of inflammatory agents may be explained by inhibition of ECL-cell histamine mobilization, consequent to enhanced formation of prostaglandin E2 by cells in the oxyntic mucosa, including the ECL cells themselves.
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PMID:Isolated rat stomach ECL cells generate prostaglandin E(2) in response to interleukin-1 beta, tumor necrosis factor-alpha and bradykinin. 1129 Mar 77

Helicobacter pylori (HP) infection is usually accompanied by an increased plasma level of gastrin, a potent mitogen able to induce cyclooxygenase (COX)-2. This study examined (a) the seroprevalence of HP, its cytotoxic protein, CagA, and cytokines (tumor necrosis factor alpha, interleukins 1beta and 8) in 80 patients with colorectal cancers, before and after the removal of tumor, compared with 160 age- and gender-matched controls; (b) the gene expression of gastrin and its receptors (CCKB-R) in the cancer tissue, (c) the plasma levels and tumor tissue contents of gastrin, and (d) the mRNA expression of COX-1, COX-2, and apoptotic proteins (Bax and Bcl2) in cancer tissue and intact colonic mucosa. Anti-HP IgG, anti-CagA IgG seroprevalence, and cytokine levels were analyzed by enzyme-linked immunosorbent assay tests; gene expressions of gastrin, CCKB-R, COX-1, COX-2, Bax, and Bcl2 by reverse transcriptase polymerase chain reaction; and gastrin by radioimmunoassay. The seroprevalence of HP, especially that expressing CagA, was significantly higher in cancer patients than in controls and did not change 1 week after tumor resection while plasma cytokines were significantly reduced after this operation. Both gastrin and CCKB-R mRNA were detected in the cancer tissue and the resection margin; similarly, COX-2 mRNA was expressed in most of cancers and their resection margin but not in intact colonic mucosa, where only COX-1 was detected. The colorectal cancer tissue contained several folds more immunoreactive gastrin than cancer resection margin and many folds more than the intact colonic mucosa. We conclude that colon adenocarcinoma and its resection margin overexpress gastrin, its receptors, CCKB-R, and COX-2, and that HP infection may contribute to colonic cancerogenesis via overexpression of gastrin and COX-2, which may account for the stimulation of the tumor growth and the reduction in apoptosis as documented by enhanced mRNA expression of anti-apoptotic Bcl2 over proapoptotic Bax proteins.
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PMID:Helicobacter pylori infection, gastrin, cyclooxygenase-2, and apoptosis in colorectal cancer. 1151 78

In rats, central vagal stimulation by thyrotropin-releasing hormone protects against ethanol-induced gastric damage by muscarinic release of prostaglandins. In contrast, gastroprotection following capsaicin-induced stimulation of afferent neurons is prostaglandin-independent. Capsaicin-evoked protection is abolished by blockade of calcitonin gene-related peptide (CGRP) receptors and inhibition of nitric oxide (NO) synthase. Various peptides including gastrin 17, cholecystokinin octapeptide, thyrotropin-releasing hormone, bombesin, corticotropin-releasing factor, epidermal growth factor, peptide YY, neurokinin A analogs and intragastric peptone exert gastroprotection that is abolished by afferent nerve denervation, blockade of CGRP receptors and inhibition of NO synthase. Indomethacin attenuates the protection of some peptides but has no effect with others. The hyperemic response to peptides is mediated by the afferent nerve/CGRP/NO system without contribution of prostaglandins. Furthermore, it was shown that NKA analogs exert afferent nerve-, CGRP- and NO-dependent gastroprotection in the face of substantial reduction of gastric mucosal blood flow indicating that gastroprotection is not necessarily mediated by mucosal hyperemia. In the rat stomach with functioning afferent nerves neither selective inhibition of cyclooxygenase (COX)-1 nor COX-2 is ulcerogenic and only simultaneous inhibition of both COX isoenzymes induees mucosal lesions. In the face of pending injury such as intragastric acid a COX-1 inhibitor evokes dose-dependent damage whereas COX-2 inhibitors are not injurious as long as the function of afferent nerves is not impaired. After afferent nerve denervation, however, COX-2 inhibitors or dexamethasone which suppresses the acid-induced up-regulation of COX-2 are highly ulcerogenic. In conclusion, release of prostaglandins following nerve stimulation can mediate protective effects under certain conditions but is not a prerequisite for neurally mediated mucosal defense. Prostaglandins are of particular importance for the maintenance of gastric mucosal integrity when neuronal defense mechanisms are impaired.
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PMID:Neural aspects of prostaglandin involvement in gastric mucosal defense. 1178 58


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