A differential dopamine receptor involvement during stress ulcer formation in rats

The involvement of dopaminergic (DA) receptors and their possible interactions were evaluated during stress ulcer formation in rats. The DA 1 antagonist SCH 23390 (0.025, 0.05, or 0.1 mg/kg) produced only marginal aggravations in gastric stress pathology when compared to vehicle controls. The DA 2 antagonist sulpiride (10 or 50 mg/kg) had dose-related effects. The lower dose aggrevated whereas the higher dose attenuated stress ulcerogenesis. The DA 2 agonist bromocryptine (2.5 or 5.0 mg/kg), however, attenuated gastric stress ulcers. Pretreatment of rats with the DA depletor α-methyl-para-tyrosine or the DA 1-antagonist SCH23390 clearly neutralized the stress ulcer-attenuating effects of bromocryptine. These results reaffirm a gastric cytoprotective role for DA and further suggest that DA 1-DA 2 receptor interactions are crucial during DAergic regulation of gastric mucosal integrity during stress.