Oxytocin pretreatment enhances arginine vasopressin-induced motor disturbances and arginine vasopressin-induced phosphoinositol hydrolysis in rat septum: a cross-sensitization phenomenon.

The recent observation that the central oxytocin (OT) receptor has high affinity for both OT and arginine vasopressin (AVP) raises the possibility that it may be involved in some of the central actions of AVP. Repeated intracerebroventricular (icv) injections of AVP in rats evoke an unusual sensitization phenomenon in that a first exposure to the peptide enhances the sensitivity (sensitization) of the brain to a second exposure. This report investigates the possibility that the OT receptor may be involved in the mediation of the phenomenon of sensitization, using OT, a specific OT receptor agonist, [Thr4,Gly7]OT, and a specific OT receptor antagonist, d(CH2)5,[Tyr(Me)2,Thr4,Tyr-NH2(9)]OVT (compound 6; cpd 6), as well as a V1 AVP receptor antagonist, d(CH2)5Tyr(Me)AVP. Peptides were injected icv in conscious, adult male Sprague-Dawley rats.(ABSTRACT TRUNCATED AT 250 WORDS)