Place preference induced by nucleus accumbens amphetamine is impaired by antagonists of ERK or p38 MAP kinases in rats

The nucleus accumbens (NAc) plays a role in conditioned place preference (CPP). The authors tested the hypothesis that inhibition of mitogen-activated protein kinases (MAPKs) would inhibit NAc-amphetamine-produced CPP. Results confirmed that NAc amphetamine increased levels of the MAPK extracellular signal-regulated kinase (ERK). In CPP studies, NAc injections (0.5 microl per side) of the ERK inhibitor PD98059 (1.0-2.5 microg) or the p38 kinase inhibitor SB203580 (15-500 ng) dose dependently impaired CPP. The c-Jun-N-terminal kinase (JNK) inhibitor SP600125 (1.0-2.5 microg) failed to block the CPP effect. The drugs did not block amphetamine-induced motor activity. Results suggest that ERK and p38, but not JNK, MAPKs may be necessary for the establishment of NAc amphetamine-produced CPP and may also mediate other forms of reward-related learning dependent on NAc.