The expression of both amphetamine-conditioned place preference and pentylenetetrazol-conditioned place aversion is attenuated by the NMDA receptor antagonist (+/-)-CPP.

The present study addressed the ability of the NMDA receptor antagonist (+/-)-CPP ((+/-)-3-(2-carboxy-piperazine-4-yl)-propyl-1-phosphonic acid) to block the expression of amphetamine (AMPH)-conditioned place preference (CPP) or pentylenetetrazol (PTZ)-conditioned place aversion (CPA) in male Wistar rats. During a 4-day conditioning period, daily injections of AMPH (1.5 mg/kg, s.c.), PTZ (20 mg/kg, i.p.) and their vehicles were paired with two distinctive compartments of the shuttle box (balanced procedure). Rats pretreated with saline showed significant preference for the AMPH-paired or aversion of PTZ-paired compartments. Pretreatment with (+/-)-CPP (10-30 mg/kg, i.p.) dose-dependently blocked the expression of both CPP and CPA. These data suggest that NMDA receptors are implicated in the expression of conditioned behaviors.