The development of behavioral sensitization to apomorphine is blocked by MK-801

The effects of the non-competitive NMDA receptor antagonist, MK-801 (dizocilpine), on the development of sensitization to the mixed dopamine receptor agonist, apomorphine were examined. Rats pretreated with MK-801 (0.25 mg/kg) prior to 2.0 mg/kg apomorphine failed to show a progressive sensitization to the activating effect of apomorphine across six preexposure sessions, nor did they show enhanced activity relative to control rats in response to 0.5 mg/kg apomorphine, given alone, during a subsequent test for sensitization. These results support the view that MK-801 interferes with long-term neural changes underlying sensitization to stimulant drugs.