Distinct effects of d-amphetamine and phencyclidine on the social behaviour of rats.

d-Amphetamine and phencyclidine (PCP) can induce a model psychosis in humans that resembles schizophrenia. Both drugs reproduce the positive symptoms of schizophrenia, but apparently only PCP mimics the negative symptoms. The purpose of this study was to determine the pharmacological profiles of d-amphetamine and PCP in the social interaction test, and to determine if they have disruptive effects on social behaviour in rats that may be comparable to the social isolation characteristic of negative symptoms. Acute and subchronic (daily for 5 days) administration of d-amphetamine (0.7-22µmol/kg) produced stereotyped behaviour at dosages of 10.4µmol/kg and upwards without any consistent effects on social behaviour. In contrast, acute and subchronic PCP (0.9-29µmol/kg) produced dose-dependent increases in stereotyped behaviour and ataxia as well as dose-dependent reductions in the social behaviour at dosages of 3.6µmol/kg and upwards. Thus, d-amphetamine and PCP had distinct effects on the social behaviour of rats. Both drugs produced stereotyped behaviour and locomotor hyperactivity, but only PCP dose-dependently disrupted social behaviour. This raises the possibility that PCP-induced social isolation in rats corresponds to the social isolation reported in humans under the influence of PCP, and that it can be used as an animal model of negative symptoms.