Rats Reared in Social Isolation Show Schizophrenia-Like Changes in Auditory Gating

Abstract

Central sensory filtering processes can be demonstrated using a paired stimulus paradigm. Normal humans show a diminished vertex-recorded midlatency auditory-evoked potential to the second of paired clicks (0.5 s apart), a phenomenon termed auditory gating. Schizophrenics routinely fail to suppress the response to the second stimulus; thus, they do not gate. Previous animal studies of auditory gating have used psychotomimetic drug administration to induce a schizophrenia-like loss. However, a nonpharmacologic model of deficient gating would be advantageous. Isolation rearing of weanling rats produces impaired prepulse startle inhibition similar to that observed in schizophrenics. The present studied examined the effects of rearing status upon auditory gating. Male Sprague–Dawley rats raised in social isolation (ISO) were compared to socially raised rats (SOC). Across 10 baseline recording sessions, SOC rats showed substantial gating, while ISO rats failed to gate. Abnormal auditory gating is transiently normalized by nicotine, but not haloperidol, in schizophrenics. ISO rats given nicotine bitartrate showed gating in the normal range for 60 min. By contrast, haloperidol failed to normalize gating in ISO rats. Thus, isolation rearing of weanling rats appears to produce a stable schizophrenia-like gating deficiency that shows the same pattern of response to pharmacological interventions.