Role of dopaminergic mechanisms in the central amygdalar nucleus in the regulation of stress-induced gastric ulcer formation in rats.

Microinjections (i/am) of dopamine (DA) antagonists, haloperidol or clozapine (1 and 5 micrograms) into the central amygdalar nucleus (CEA) produced dose-related aggravations in cold-restraint (3 h at 4 degrees C) stress-induced gastric ulcer formation in rats. On the other hand, DA (10 micrograms, i/am), its agonist, apomorphine (5 mg/kg, ip) and its precursor, l-Dopa (100 mg/kg, ip) significantly inhibited stress ulcerogenesis. Pretreatment of rats (i/am) with clozapine antagonized or reversed the gastric cytoprotective effects of DA, apomorphine and l-Dopa. The results indicate that the CEA is important for the observed gastric cytomodulatory effects of both centrally and peripherally administered dopaminergic agents during stressful experiences.