Abstract:Primary cultures of rat ventral mesencephalon were used to elucidate the role of chronic stimulation of dopamine (DA) D2autoreceptors in the development of fetal dopaminergic neurons in vitro. Cultured dopaminergic neurons, as visualized by tyrosine hydroxylase immunocytochemistry, became more differentiated in the course of cultivation time and exhibited specific high‐affinity uptake for [3H]DA. In rat striatal tissue, activation of D2receptors has been shown to inhibit the release of DA. Previously accumulated [3H]DA was released from the cultures upon depolarization in a Ca2+‐dependent manner. K+‐evoked [3H]DA release could be inhibited by the selective D2receptor agonists LY 171555 and N0437 in a concentration‐dependent manner. The inhibitory effects of LY 171555 and N0437 were antagonized by the selective DA D2receptor antagonist sulpiride. These observations are indicative for the expression of functional D2receptors in the cultures. Daily treatment of these cultures for 7 days with LY 171555 or sulpiride did not lead to any change in protein content, the number of tyrosine hydroxylase‐immunoreactive neurons, or the uptake capacity for [3H]DA. Our data demonstrate that chronic stimulation of DA D2receptors does not impair survival or differentiation of cultured fetal dopaminergi