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Olanzapine and risperidone disrupt conditioned avoidance responding in phencyclidine-pretreated or amphetamine-pretreated rats by selectively weakening motivational salience of conditioned stimulus

Li, Ming; He, Wei; Mead, Alexa

doi: 10.1097/FBP.0b013e3283243008
Original Articles

The rat conditioned avoidance response model is a well-established preclinical behavioral model predictive of antipsychotic efficacy. All clinically approved antipsychotic drugs disrupt conditioned avoidance responding – a feature that distinguishes them from other psychotherapeutics. We previously showed that the typical antipsychotic drug haloperidol disrupts avoidance responding by progressively attenuating the motivational salience of the conditioned stimulus (CS) in normal rats. In this study, using two pharmacological rat models of schizophrenia [e.g. phencyclidine (PCP) or amphetamine sensitization], we examined whether atypicals such as olanzapine or risperidone disrupt avoidance responding through the same behavioral mechanism. Rats were first pretreated with PCP, amphetamine, or saline under one of two different injection schedules for either 1 or 3 weeks. They were then trained to acquire avoidance responding to two types of CS (CS1 and CS2) that differed in their ability to predict the occurrence of the unconditioned stimulus. Finally, rats were tested repeatedly under olanzapine (1.0 mg/kg, subcutaneously) or risperidone (0.33 mg/kg, subcutaneously) daily for 5 or 7 consecutive days. We found that repeated olanzapine or risperidone treatment produced a progressive across-session decline in avoidance responding to both CS1 and CS2. Olanzapine and risperidone disrupted the CS2 (a less salient CS) avoidance to a greater extent than the CS1 avoidance. Pretreatment with PCP and amphetamine did not affect the disruptive effect of olanzapine or risperidone on avoidance responding. On the basis of these findings, we suggest that the atypical drugs olanzapine and risperidone, like the typical drug haloperidol, also disrupt avoidance responding primarily by attenuating the motivational salience of the CS.

Department of Psychology, University of Nebraska-Lincoln, Lincoln, Nebraska, USA

Correspondence to Assistant Professor Ming Li, PhD, Department of Psychology, University of Nebraska-Lincoln, 238 Burnett Hall, Lincoln, NE 68588, USA


Received 29 August 2008 Accepted as revised 25 November 2008

© 2009 Lippincott Williams & Wilkins, Inc.