The effect of surgical castration of adult male Sprague-Dawley rats on peripheral and central benzodiazepine (BZ) receptors was studied. Following removal of the testes, a significant decrease in the ...density of peripheral BZ receptors (PBR) was observed in Cowper's glands (71%; P less than 0.005) and the adrenal (31%; P less than 0.01), but not in the heart. Administration of testosterone acetate (TA) prevented castration-induced PBR depletion. Orchiectomy per se, as well as TA administration to castrated rats, had no effect on central or peripheral BZ receptors in whole brain without the cerebellum. These results indicate the regulatory role of testosterone in the regulation of PBR in Cowper's glands and adrenal.
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.
