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 f ever may modulate the motor actions of exogenous AVP. Intracerebrovent ricular (icv) injection of interleukin-1alpha (IL-1alpha, 40 ng) elici ted 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 ea rlier) rats. At the end of the 2nd h, administration of AVP (1 pmol ic v), but not OT (10 pmol icv), significantly suppressed the febrile res ponse in OT-pretreated but not in saline-pretreated rats. In nonfebril e OT-pretreated rats, 10 but not 1 pmol of AVP (icv) caused a signific ant decrease in body temperature. In rats pretreated with IL-1alpha (4 0 ng icv) injection of AVP (100 pmol icv) induced enhanced motor respo nses. In summary, the ability of OT pretreatment to alter the febrile response to IL-1alpha and the antipyretic action of AVP suggests a rol e for this peptide in fever. Furthermore, the observation that fever p retreatment can lower the threshold for convulsive-like behavior evoke d 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.