The influence of dopamine agonists and antagonists on gastric lesions in mice.

The dopamine agonist bromocriptine and L-dopa significantly inhibited whereas dopamine antagonist haloperidol aggravated the gastric lesions induced by pylorus ligation in mice as found earlier for rats. Furthermore, the successful use of a dopamine antagonist alone for the induction of gastric lesions also in mice was demonstrated, since the gastric lesions were induced by a single dose of haloperidol without any additional noxious treatment. Bromocriptine successfully inhibited both the gastric lesion-potentiating as well as the gastric lesion-inducing effect of haloperidol.

Dopamine antagonists induce gastric lesions in rats.

Gastric lesions were provoked in all rats that had received intraperitoneally a single dose of the dopamine antagonists haloperidol, metoclopramide or domperidone 24 h before. Dose-dependence was demonstrated for haloperidol. This drug induced gastric lesions as early as 90 min after its application.

Preliminary investigations of the metabolism and pharmacological activity of beta-hydroxytryptamines in mammals.

beta-Hydroxytryptamine and beta-hydroxy-5-hydroxytryptamine were incubated with rat liver slices and oxidative deamination was established as the main route of metabolism: in both instances the corresponding indole-3-glycollic acids and indole-3-ethane diols were the major metabolites. However, the rates of deamination of beta-hydroxylated tryptamines, as measured manometrically, were found to be much slower than those of tryptamines nonhydroxylated in the side chain. The pharmacological activities of beta-hydroxylated tryptamines were tested in guinea-pigs on resistance of respiratory pathways, spontaneous respiration, electrocardiogram, blood pressure and isolated ileum, using tryptamine and 5-HT as reference substances.