Diazepam in the ventral striatum dissociates dopamine-dependent and dopamine-independent place conditioning

We have previously shown that diazepam blocks both the formation and the ex pression of amphetamine-induced conditioned place preference (CPP), bur has no effect on the CPP induced by morphine. Because diazepam reducer dopamin e activity in the nucleus accumbens, three experiments were conducted in or der to investigate whether diazepam selectively blocks the expression of pl ace conditioning dependent on mesolimbic dopamine. The first experiment fou nd that systemic diazepam blocked the expression of conditioned place avers ion induced by the kappa-receptor agonist U50-488. The second and third exp eriments demonstrated that intra-cranial injections of diazepam in the nucl eus accumbens blocked the expression of amphetamine CPP but not of morphine CPP. It is concluded that diazepam interferes with mesolimbic dopamine-dep endent motivational effects of drugs. NeuroReport 11:2553-2557 (C) 2000 Lip pincott Williams & Wilkins.