Central alpha 2-adrenoceptor-mediated inhibition of gastric motility in rats.

We investigated the subtype of alpha-adrenoceptors participating in central noradrenergic inhibition of gastric motility in urethane-anesthetized rats. Noradrenaline at 10 nmole administered intracisternally (i.c.) significantly decreased gastric motility. Yohimbine at 10 nmole, i.c., but not the same dose of prazosin, abolished this noradrenaline-induced decrease in gastric motility. Clonidine at 10 nmole, i.c., but not phenylephrine at 20 nmole, significantly decreased gastric motility. These results suggest that alpha 2-adrenoceptor-mediated mechanisms in the brain stem are involved in noradrenergic inhibitory regulation of gastric motility.