Nicotine applied into the dorsal motor nucleus of the vagus inhibits enhanced gastric acid output and mucosal blood flow in rats.

The effects of nicotine microinjected into several brain regions on the centrally elevated gastric acid output and mucosal blood flow (MBF) were examined in anesthetized rats. Intravenous administration of 2-deoxy-D-glucose (2-DG) induced increases in gastric acid output and MBF. These increases were inhibited dose dependently by nicotine microinjected into the dorsal motor nucleus of the vagus (NDV) but not into various hypothalamic regions. This effect of nicotine was abolished with concomitantly administered hexamethonium and was not observed in reserpine-pretreated animals. Electrical stimulation of the lateral hypothalamic area (LHA) induced an increase in gastric acid output. This increase was completely inhibited when nicotine was microinjected into the NDV 5 min before stimulation. This inhibitory effect of nicotine was abolished by concomitantly administered hexamethonium and by intraventricular pretreatment with phentolamine, but not with propranolol. These results suggest that activation of nicotinic receptors within the NDV releases noradrenaline and that there is a resultant inhibition of gastric acid output and MBF.