Chronic domperidone fails to increase striatal spiperone binding sites despite hyperprolactinemia: comparison with chronic haloperidol.

Mice were administered the dopaminergic antagonists haloperidol or domperidone in their drinking water for 2 or 21 days. Serum prolactin levels and striatal 3H-spiperone-binding sites (D-2 receptors) were compared to vehicle-treated controls. While only domperidone elevated serum prolactin levels, only haloperidol increased the density of striatal 3H-spiperone-binding site. The failure of domperidone, a potent D-2 receptor antagonist, to increase striatal receptor number is attributed to its poor penetration of the blood-brain barrier. These results indicate that peripheral effects of neuroleptic drugs, including prolactin elevation, are not sufficient for the development of dopaminergic supersensitivity in the central nervous system.