Differential effects of acute amphetamine and phencyclidine treatment and withdrawal from repeated amphetamine or phencyclidine treatment on social interaction and social memory in rats

Although animal models based on amphetamine (AMPH) or phencyclidine (PCP) treatment have been used extensively to study the neurobiological and behavioral characteristics of schizophrenia, there are conflicting reports regarding their validity in modeling the negative symptoms and cognitive deficits of schizophrenia. The present study examined how acute AMPH or PCP treatment (Experiment 1) and withdrawal from repeated AMPH treatment (Experiment 2) or PCP treatment (Experiment 3) affects social behavior and social recognition memory in male Sprague-Dawley rats. Each subject was tested on two consecutive days. On the first day, the rats were tested four times (5 min/each) at 10-min intervals with the same partner rat (termed "AAAA" day). One day later, the rats were tested with the previous partner in the first three sessions and with a new partner rat in the final session (termed "AAAB" day). The results show that acute AMPH treatment (1.5 mg/kg, sc) significantly reduced the time spent on social interaction, but did not affect social recognition on the first day. Acute AMPH only disrupted social recognition on the second day of drug testing. In contrast, acute PCP treatment (2.0 mg/kg, sc) had no effect on time spent on social interaction, but did significantly disrupt social recognition on both days. Withdrawal from repeated AMPH (3.0 mg/kg/day for 7 days, ip) or PCP (5.0 mg/kg/twice daily for 7 days, ip) treatment did not affect social interaction or social recognition, indicating a lack of long-term detrimental effect of repeated AMPH or PCP treatment. These results suggest that acute AMPH treatment at a low dose (1.5 mg/kg) may be useful in modeling social withdrawal symptoms of schizophrenia, whereas acute PCP treatment at a similar dose range (2.0 mg/kg) may be useful in modeling the social cognitive deficit of schizophrenia.