Enhanced stereotypic behavior by chronic treatment with bromocriptine accompanies increase of D-1 receptor binding

Different effects of chronic treatment with bromocriptine (BRO) on D-1 and D-2 receptors in the rat were studied through behavioral observation and DA receptor binding assays. Chronic BRO led to enhancement of stereotypy to apomorphine (APO), at the same time it increased the density of D-1 receptor binding by 43% and decreased that of D-2 receptor binding by 21%. Our data suggest that BRO has different effects on D-1 and D-2 receptors and the behavioral hypersensitivity caused by BRO may be relevant to the proliferation of D-1 receptor.