[Effects of dopamine receptor agonists and antagonists on an experimental ulcer system induced by cysteamine in rats--dopaminergic mechanism vs pathogenesis of peptic ulceration].

The physiological roles of sympathetic nerve system in the stomach has been thought to be very important in the pathogenesis of peptic ulceration. The aim of this study was to examine the effects of dopamine receptor agonists and antagonists on gastric acid secretion and gastroduodenal ulcer formation induced by cysteamine injection in rats. Cysteamine was given by subcutaneous injection as 400mg/kg in doses. Dopamine was given by continuous iv infusion as 2, 4 and 8 micrograms/kg/min in doses. Domperidone regarded as antagonists of D2 receptor was given by continuous iv infusion as 2 micrograms/kg/min in doses. As a result of acid output measured during infusion of dopamine alone or dopamine with domperidone in non-vagotomized or vagotomized rats, increasing effects of dopamine on acid output were depended on dopaminergic mechanism, and decreasing effects of dopamine on acid output were depended on dopaminergic mechanism in rami vagus. As a result of duodenal and gastric ulcer index, ulcerogenicity of cysteamine in the stomach was concerned with dopaminergic mechanism more than that of in the duodenum. These results suggested that the pathogenesis of experimental ulcer induced by cysteamine injection was depended on dopamine receptor in the stomach.