Place-aversion conditioned by phencyclidine in rats: development of tolerance and pharmacologic antagonism

The pharmacologic properties of phencyclidine were assessed in adult, male rats using a three-chambered, place-conditioning apparatus. Phencyclidine hydrochloride (PCP), at doses of 0.5 to 4 mg/kg, produced a dose-related place-aversion after three drug/environment pairings. During the place-conditioning procedure, 4 mg/kg of PCP significantly increased spontaneous locomotor activity compared to saline-control. Tolerance to PCP-induced place-aversion developed after four daily administrations of 4 mg/kg of PCP. d-Butaclamol, 0.4 mg/kg, given 1 min before each of the three conditioning-doses of PCP decreased the development of the place-aversion induced by PCP. 1-Butaclamol was without significant effect. Spiroperidol, 0.06 mg/kg, completely blocked the development of PCP place-aversion. Spiroperidol and the stereoisomers of butaclamol did not have significant place-conditioning activity when administered alone in the place-conditioning paradigm. The data suggest that PCP induces place-aversion in rats in the place-conditioning model, and that tolerance to this effect develops within 4 days. Furthermore, since d-butaclamol or spiroperidol, but not 1-butaclamol, antagonized this effect of PCP, PCP-induced place-aversion may be mediated in part by a dopaminergic mechanism.