Environmental animal models for sensorimotor gating deficiencies in schizophrenia: a review

Rationale: In schizophrenia research, the study of animal models has receiv ed considerable attention in the past 20 years. The value of animal models in preclinical research is widely recognised, largely because they can prov ide precious knowledge regarding the neurobiology of schizophrenia and can also be used for developing antipsychotic drugs. Prepulse inhibition (PPI; reduction in startle reflex induced by a prestimulus) is impaired in schizo phrenic patients, a finding that has been associated with a loss of sensori motor gating abilities. In rats, the schizophrenic-like PPI deficit can be induced by pharmacological or surgical manipulations targeting mainly the c ortico-meso-limbic circuitry. Objectives: The literature was critically rev iewed in an effort to determine the robustness and the relevance for schizo phrenia of another category of animal models, based purely on manipulations of the social environment, that encompasses the neurodevelopmental hypothe sis of schizophrenia. Specifically, we focused our attention on the long-te rm effects of such environmental models on sensorimotor gating processes as assessed in the PPI paradigm, with an attempt to evaluate their face, pred ictive and construct validity. Results: Our review of the literature leads to the conclusion that social deprivation performed directly after weaning (similar to 21 days of age) is more likely to be a relevant model for PPI i mpairments in schizophrenia than pre-weaning manipulations. Conclusions: Al though the robustness of such environmental models requires further study, these animal models offer the advantage of avoiding invasive manipulations, which allows for a variety of anatomical, electrophysiological, neuroendoc rine or neurochemical investigations in the absence of confounding pharmaco logical or surgical effects.