Chronic phencyclidine treatment increases dendritic spine density in prefrontal cortex and nucleus accumbens neurons.

We examined whether repeated exposure to the noncompetitive NMDA receptor antagonist phencyclidine (PCP) produces enduring changes in dendritic structure in a manner similar to the stimulants cocaine and amphetamine. Adult rats were treated with i.p. injections of PCP (5 mg/kg) or saline, twice a day, for 5 consecutive days, for a total of 4 weeks. One month after the last injection, their brains were removed and processed for Golgi-Cox staining. Prior exposure to PCP increased dendritic spine density in the mPFC and NAcc core, but not in the parietal cortex. These findings, which are similar to those observed after chronic treatment with cocaine and amphetamine, raise the possibility that, despite differences in their mechanisms of action, PCP and stimulant drugs may induce some of their enduring effects via common processes.