Convulsive and hypothermic effects of vasopressin in the brain of the rat.

Arginine vasopressin (AVP) was administered into the lateral cerebral ventricles of rats to assess its effects when given directly into the brain. AVP (1.0 microgram) caused an immediate sharp decrease in body temperature. Behaviorally, AVP caused short pauses of immobility and staring upon the first injection but the same dose caused myoclonic-myotonic convulsions upon the second injection 2 days later. Thereafter, as little as 10 ng of AVP caused seizures.