Possible involvement of brain oxytocin in modulating vasopressin antipyretic action.

Experiments were undertaken to test whether oxytocin (OT) may modulate the antipyretic action of arginine vasopressin (AVP) and to determine whether the action of endogenously released OT and/or AVP evoked by fever may modulate the motor actions of exogenous AVP. Intracerebroventricular (icv) injection of interleukin-1 alpha (IL-1 alpha, 40 ng) elicited a significantly attenuated rise in body temperature during the 2nd h of the febrile responses in OT-pretreated (0.1-10 pmol icv, 24 h earlier) rats. At the end of the 2nd h, administration of AVP (1 pmol icv), but not OT (10 pmol icv), significantly suppressed the febrile response in OT-pretreated but not in saline-pretreated rats. In nonfebrile OT-pretreated rats, 10 but not 1 pmol of AVP (icv) caused a significant decrease in body temperature. In rats pretreated with IL-1 alpha (40 ng icv) injection of AVP (100 pmol icv) induced enhanced motor responses. In summary, the ability of OT pretreatment to alter the febrile response to IL-1 alpha and the antipyretic action of AVP suggests a role for this peptide in fever. Furthermore, the observation that fever pretreatment can lower the threshold for convulsive-like behavior evoked by subsequent exposure to AVP raises the possibility that central OT and/or AVP released during fever could play a role in the genesis of febrile convulsions.