Central noradrenergic inhibition of gastric motility in rats.

The roles of central noradrenergic mechanisms in the regulation of gastric motility were investigated in urethane-anesthetized rats in whom an intragastric balloon had been placed. Noradrenaline 100 nmol administered intracerebroventricularly (i.c.v.) significantly decreased spontaneous contractions of the stomach and this decrease in gastric motility was not observed in bilaterally vagotomized animals. Intracisternally administered (i.c.) noradrenaline (10 nmol) induced a decrease in gastric motility comparable to that elicited by noradrenaline 100 nmol i.c.v. Phentolamine 10 nmol i.c. but not the same dose of propranolol i.c. significantly antagonized the noradrenaline (10 nmol)-induced inhibition of gastric motility. These results suggest that alpha-adrenoceptor-mediated noradrenergic mechanisms in the brain stem are involved in the inhibitory regulation of gastric motility.