THE EFFECTS OF SUBCUTANEOUS ADMINISTRATION OF ARGININE-8-VASOPRESSIN ON THE ELECTROENCEPHALOGRAM OF CONSCIOUS RATS ARE MEDIATED BY PERIPHERAL VASOPRESSIN V-1 RECEPTORS

The effects of subcutaneous (s.c.) administration of arginine-8 vasopr essin (AVP) were investigated on the electroencephalogram (EEG) of con scious rats, AVP (1 mcg/kg) had no effect on the EEG. However, AVP (5 and 10 mcg/kg) produced significant changes in the spectral power of t he EEG in a manner that was consistent with increase in level of arous al. Analogs of AVP which are virtually devoid of vasopressin V-1 recep tor agonist activity, desglycinamide-9-arginine-8 vasopressin (10 mcg/ kg, s.c.) and 1-deamino-8-D arginine-8-vasopressin (10 mcg/kg, s.c.), had no effect on the EEG. Pretreatment with 1-(beta-mercapto-beta,beta -cyclopentamethylene propionic acid) 2(O-methyl) tyrosine arginine-8 v asopressin (10 mcg/kg), a vasopressin V-1 receptor antagonist, abolish ed the effects of AVP (10 mcg/kg) on the EEG. As systemically administ ered AVP cannot cross the blood-brain barrier the present results indi cate that the effects of s.c. AVP on the EEG of conscious rats are med iated by peripheral vasopressin V-1 receptors.