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 DA1 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 DA2 antagonist sulpiride (10 or 50 mg/kg) had dose-related effects. The lower dose aggravated whereas the higher dose attenuated stress ulcerogenesis. The DA2 agonist bromocriptine (2.5 or 5.0 mg/kg), however, attenuated gastric stress ulcers. Pretreatment of rats with the DA depletor alpha-methyl-para-tyrosine or the DA1-antagonist SCH23390 clearly neutralized the stress ulcer-attenuating effects of bromocriptine. These results reaffirm a gastric cytoprotective role for DA and further suggest that DA1-DA2 receptor interactions are crucial during DAergic regulation of gastric mucosal integrity during stress.