Dual effects of intracerebroventricularly applied nicotine on gastric motility in rats.

Intracerebroventricularly (i. c. v.) administered nicotine induced a decrease followed by an increase in gastric motility in urethane-anesthetized rats. These effects of i. c. v. administered nicotine were antagonized by simultaneously i. c. v. administered hexamethonium. Both vagotomy and pretreatment with atropine abolished the increasing effect of i. c. v. administered nicotine. In vagotomized rats, i. c. v. administered nicotine did not cause any decrease in gastric motility after elevation by electrical stimulation of the vagus nerve. These results suggest that i. c. v. administered nicotine activates central nicotinic receptors and that the vagus nerve is involved in both the inhibitory and stimulatory effects of i. c. v. administered nicotine on gastric motility.