ISOLATION REARING OF RATS PRODUCES A DEFICIT IN PREPULSE INHIBITION OF ACOUSTIC STARTLE SIMILAR TO THAT IN SCHIZOPHRENIA

Schizophrenic patients exhibit deficits in the prepulse inhibition of startle, an operational measure of the sensorimotor gating deficits th at are theorized to contribute to cognitive disorganization. In rats, the activation of mesolimbic dopamine (DA) disrupts prepulse inhibitio n, providing a useful model of the similar deficits in sensorimotor ga ting in schizophrenic patients. Rats reared in isolation exhibit neuro chemical and behavioral abnormalities suggestive of hyperactivity in m esolimbic DA systems. In the present studies, rats reared in social gr oups or in isolation were tested in startle response paradigms using 1 20 or 105 dB acoustic pulses, some of which were preceded (100 msec) b y prepulses that were 2, 4, 8, or 16 dB above the 65 dB background. Is olation-reared animals were hyperreactive only in response to the init lal few startle stimuli. The amount of prepulse inhibition was decreas ed significantly in isolation-reared animals, particularly when midran ge 8 dB prepulses were used. A subsequent study replicated the effect of isolation rearing on prepulse inhibition and suggested that the def icit in sensorimotor gating exhibited by isolation-reared animals may be normalized by the administration of the DA antagonist raclopride (0 .05 mg/kg). Hence, isolation rearing provides a nonpharmacological way to induce in rats a deficit in sensorimotor gating that is exhibited by schizophrenic patients.