Journal of physiology and pharmacology : an official journal of the Polish Physiological Society
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J. Physiol. Pharmacol. · Jul 2004
Comparative StudyModulation of pancreatic enzyme secretion by melatonin and its precursor; L-tryptophan. Role of CCK and afferent nerves.
Melatonin, a pineal hormone, is also produced in the gastrointestinal tract. Melatonin receptors have been detected in the stomach, intestine and pancreas. This indole inhibits insulin secretion but its role in the physiological modulation of exocrine pancreatic function is yet unknown. ⋯ Deactivation of sensory nerves by capsaicin or administration of CCK(1) - receptor antagonist; tarazepide, reversed the stimulatory effects of melatonin or L-tryptophan on pancreatic secretory function. Administration of melatonin or its amino-acid precursor to the rats resulted in the significant and dose-dependent rises of melatonin and CCK plasma levels. We conclude that melatonin or its precursor; L-tryptophan stimulates pancreatic enzyme secretion via stimulation of CCK release and activation of duodeno-pancreatic reflexes.
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J. Physiol. Pharmacol. · Dec 2003
Historical ArticleExperimental production of peptic ulcer, gastric damage and cancer models and their use in pathophysiological studies and pharmacological treatment--Polish achievements.
The common acid related diseases of the upper GI tract could be considered as primarily due to the defect in barrier function either of the gastric mucosal or duodenal epithelium leading to the formation of gastric or duodenal ulcers. An attempt was made in this chapter to discuss the history of peptic ulcer disease in humans and methods for the production of acute gastric lesions and ulcers in experimental animals with the special attention focused to the contribution of Polish scientists and investigators into this field. Early surgical advances in the management of peptic ulcers were emphasized that were then subsequently replaced by pharmacological treatment (histamine H(2)-receptor antagonists, proton pump inhibitors) and considered as the major strategy against the acid disorders. ⋯ Detailed studies revealed, however, that PG-induced cytoprotection offers a short-term protection against gastric lesions induced by corrosive agents but unfortunately this phenomenon gives a little, if any, impact to the process of ulcer healing. The experimental studies on healing of gastric ulcers that become supportive for the clinical trial in humans, performed also by Polish pioneers and the effect of numerous growth factors (EGF, TGF alpha), NO inhibitors, cyclooxygenase- (COX)-1 and COX-2 inhibitors and new safer derivatives of NSAID releasing NO in protection and ulcer healing are discussed. Finally, the major discovery by Warren and Marshall of H. pylori that have been studied world-wide in experimental animals including also Polish investigators, allowed for the better insight to the pathological consequences of this germ infection in the gastric mucosa and helped to establish the anti-H. pylori eradication therapy.
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J. Physiol. Pharmacol. · Dec 2003
ReviewVisceral sensitivity perturbation integration in the brain-gut axis in functional digestive disorders.
Chronic abdominal pain is the most distressing symptom in patients with functional digestive disorders (FDD). IBS is the most common gastrointestinal disorder seen in primary care and gastroenterology practice. IBS is a functional bowel disorder in which abdominal pain is associated with defaecation or a change in bowel habit, with features of disordered defecation and with distension. ⋯ In contrast, in a women predominant population of IBS patients, we did not observed any neuronal activation in locations activated in healthy volunteers (ACC, dorsolateral PFC) while a significant deactivation was observed in the IC and in the amygdala, a limbic structure with a role to assign emotional significance to a current experience related to anxiety and fear. Brain imaging techniques thus appear as useful tools to characterize normal and abnormal brain processing of visceral pain in patients with FDD. Reversal effects of chemical compounds targeting these abnormalities either at a peripheral or a central level should be of interest.
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J. Physiol. Pharmacol. · Mar 2003
Triple eradication therapy counteracts functional impairment associated with Helicobacter pylori infection in Mongolian gerbils.
Gastric Helicobacter pylori (Hp) infection in Mongolian gerbils is an established experimental model of gastric carcinogenesis resulting from the long-term Hp infection but functional aspects accompanying this Hp-induced progression from gastritis to the cancer, especially changes in gastric acid secretion, gastric blood flow (GBF) and gastrin-somatostatin link have been little studied. It is unclear whether Hp eradication therapy alters the functional and the histopathological changes in this animal model of Hp-infection. We examined the effects of intragastric (i.g.) inoculation of Mongolian gerbils with Hp strain (cagA+ vacA+, 5 x 10(6) CFU/ml) that had been isolated from a patient with gastric ulcer as compared to those induced by vehicle (saline) in gerbils with or without gastric fistula (GF) at 1.2, 4, 6, 9, 12 and 30 wks upon gastric inoculation with this bacteria. ⋯ The GBF in Hp-infected gerbils was significantly lower, and a 6-7 fold increase in plasma gastrin levels combined with a significant fall in gastric luminal somatostatin contents observed at all tested periods as compared to vehicle-controls and these effects were counteracted by anti-Hp triple therapy. We conclude that: 1). Hp-infection in Mongolian gerbils in early stages before adenocarcinoma formation results in the development of typical functional and pathological changes such as suppression of gastric secretion and impairment of both, gastric mucosal microcirculation and gastrin-somatostatin link, and 2). this deleterious influence of Hp on gastric morphology and gastric functions is greatly attenuated in gerbils treated with Hp-eradication therapy.
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J. Physiol. Pharmacol. · Dec 2002
No-dependent vasodilation induced by nebivolol in coronary circulation is not mediated by beta-adrenoceptors or by 5 HT1A-receptors.
Nebivolol is a unique beta1-adrenoceptor antagonist which possesses peripheral vasodilator properties dependent on endothelial NO. Nebivolol-induced release of NO was attributed to its L stereoisomer and to its ability to stimulate endothelial beta2, beta3 adrenoceptors or 5-HT1A receptors. Here, in the isolated guinea pig heart we analysed coronary vasodilator potency of L- and D-nebivolol and a possible role of beta2, beta3 adrenoceptors and 5-HT1A receptors in nebivolol-induced vasodilation. ⋯ The nonselective beta1/beta2-adrenoceptor antagonist--nadolol (10(-5) M), the selective beta3-adrenoceptor antagonist--L 748337 (10(-6) M) and the 5 HT1A receptor antagonist--NAN 190 (5 x 10(-6) M), none of them inhibited coronary vasodilation induced by D- and L-nebivolol. In summary, in the isolated guinea pig heart both D- and L-nebivolol act as coronary vasodilators. Coronary vasodilation induced by stereoisomers of nebivolol is mediated by endothelium-derived NO and does not depend on beta2, beta3 adrenoceptors or 5 HT1A receptors.