Centrally administered vasopressin antagonizes pentobarbital-induced narcosis and depression of hippocampal cholinergic activity

Intracerebroventricular (ICV) microinjection of arginine vasopressin (AVP) to pentobarbital-anesthetized rats produced shortening of the duration of narcosis. This analeptic effect was blocked by atropine, indicating the central cholinergic nature of the response. AVP also increased hippocampal sodium-dependent high affinity choline uptake activity that had been depressed by the barbiturate. The AVP analeptic effect was blocked by pretreatment with a V-1 (vasopressor), but not a V-2 (antidiuretic), vasopressin receptor antagonist. These results suggest that ICV AVP produces its analeptic effect by interacting with central V-1 receptors to activate a hippocampal cholinergic arousal system. The cholinergic arousal effect may be a factor in the memory enhancing property of AVP.