Adrenal mitochondrial benzodiazepine receptors are sensitive to agents active at the dopamine receptor

Male rats were treated for 21 days with drugs known to affect prolactin secretion, in order to assess the effects of these drugs on mitochondrial benzodiazepine receptors (MBRs). Sulpiride, a selective dopamine D2 receptor antagonist and hyperprolactinemic agent, decreased MBR density in the adrenal gland (49%; P < 0.005), whereas metoclopramide, another dopamine antagonist with a preference for dopamine D2 receptors, increased adrenal gland MBR density (31%; P < 0.05). Bromocriptine, a specific dopamine agonist, increased MBR density in this organ (87%; P < 0.001). None of the three agents influenced kidney or testicular MBRs. These data indicate that the mechanism of organ-specific alterations in MBRs seems to be prolactin independent.