Effects of dopamine agonists and antagonists on gastric acid secretion and stress responses in rats.

The dopamine agonists and promoters bromocriptine, bupropion, and p-hydroxymethylphenidate (a peripherally acting methylphenidate analog) reduced basal gastric acid secretion in rats, while the dopamine antagonists haloperidol, pimozide and metoclopramide augmented gastric acid output. Stress ulcer formation and plasma corticosterone levels were markedly reduced by l-dopa given either intraperitoneally or intracerebroventricularly as well as by intraperitoneally administered p-hydroxymethylphenidate. Domperidone, a peripheral dopamine receptor blocker, produced variable effects on stress responses, indicating a wider spectrum of action than hitherto realized for this compound. The results strongly support a role for both central and peripheral dopaminergic activity in reducing the pathological consequences of exposure to stress.