CHRONIC TREATMENT WITH HALOPERIDOL DIMINISHES THE PHENCYCLIDINE-INDUCED SENSORIMOTOR GATING DEFICIT IN RATS

Prepulse inhibition is a model in which a weak subthreshold stimulus ( prepulse), presented to an individual before a strong stimulus (pulse) , inhibits a startle response to the latter. A deficit of prepulse inh ibition induced by dopaminomimetics and antagonists of NMDA receptors has been suggested as an animal model of the sensorimotor deficit in s chizophrenia. The aim of the present study was to examine the effect o f chronic treatment with the classic neuroleptic haloperidol on the di sruption of prepulse inhibition induced by the uncompetitive antagonis t of NMDA receptors phencyclidine (PCP, 5 mg/kg sc). Haloperidol in a dose of 1 mg/kg/day was given to rats in drinking water for 3 months. The PCP-induced reduction in prepulse inhibition was not reversed by s hort-term (4-day) haloperidol administration. In contrast, long-term t reatment with haloperidol (6 weeks or 3 months) diminished the PCP-ind uced effect. The present study suggests that the improvement in sensor imotor gating in the PCP model in rats by prolonged treatment with hal operidol may reflect its antipsychotic action.