In vivo release of dopamine in the nucleus accumbens of the rat: modulation by cholecystokinin.

We observed that the release of endogenous dopamine (DA), induced by perfusion of a 55 mM K+-containing buffer in the nucleus accumbens, was Ca2+-dependent and confined to a local region. We also demonstrated that the sulphated form of cholecystokinin octapeptide, but not the unsulphated form, suppressed this stimulated release of dopamine in a concentration-dependent manner. This suggests that cholecystokinin may act as a functional antagonist to dopamine within this structure.