Oxytocin modulates psychotomimetic-induced deficits in sensorimotor gating

Oxytocin plays an important role in the regulation of normal cognitive func tions and behaviors, which are disturbed in schizophrenia. Several, studies suggest that oxytocinergic function is abnormal in schizophrenia patients. Thus, oxytocin may be involved in the pathophysiology associated with this disorder. This study investigated the regulatory effects of oxytocin on de ficits in prepulse inhibition (PPI) associated with schizophrenia. Prepulse inhibition (PPH) is an operational measure of sensorimotor gating which ca n be measured across many species. PPI is the normal suppression of the sta rtle reflex when the intense startling stimulus ("pulse") is immediately pr eceded by a weaker stimulus ("prepulse"). Subcutaneously administered oxyto cin (0.04-1.0 mg/kg) dose-dependently restored PPI that had been reduced in rats by dizocilpine, a non-competitive NMDA antagonist, and by amphetamine , an indirect dopamine agonist. Oxytocin did not produce a significant effe ct on baseline PPI or PPI decreased by the direct dopamine agonist, apomorp hine. The underlying startle response amplitude was also not significantly altered by oxytocin. These results suggest that oxytocin may play an import ant role in the modulation of dopaminergic and glutamatergic regulation of PPI, and that it may act as a novel endogenous antipsychotic.