The effect of bromocriptine on basal and histamine-stimulated gastric acid secretion in anesthetized rats

Introduction: The protective and antisecretory effects of dopamine agonists on the stomach have been already reported, but the effect of bromocriptine (D2 dopamine agonist) on histamine stimulated gastric acid secretion (GAS) needs to be investigated. Methods: For gastric sampling, animals were anesthetized and a polyethylen tube was introduced into the stomach through esophagus. A cannula was also inserted into the pyloroduodenal junction and passed up into the stomach. Results: Our data showed that administration of bromocriptine (2 mg/kg), 60 minutes before histamine infusion, did not affect basal acid secretion but significantly reduced histamine-induced GAS (P<0.01). Also, simultaneous application of bromocriptine and histamine-infusion (0.8 mg/100g/h) had no effect on histamine-stimulated gastric acid secretion. The inhibitory effect of bromocriptine on GAS did not change by sulpiride, a D2 dopamine antagonist. Plasma glucose level was constant in our experimental conditions. Conclusion: Based on our data, we concluded that inhibitory effect of bromocriptine (2 mg/kg) on histamine stimulated acid output was probably mediated by non dopaminergic receptors or unknown subtypes of D2 receptors which are not sensitive to sulpiride.