Hormonal regulation of peripheral benzodiazepine binding sites in female rat adrenal Gland and kidney

The effect of hypophysectomy and hormonal replacement on the density of peripheral benzodiazepine binding sites (PBS) in rat adrenal gland and kidney was studied. In the adrenal gland, hypophysectomy caused a significant decrease of 3-fold in PBS density. In the kidney, in contrast, hypophysectomy did not affect PBS density. In the adrenal gland, adrenocorticotropic hormone (ACTH) administered to hypophysectomized rats caused a significant increase of more than 5-fold in PBS density compared to untreated hypophysectomized rats, and of more than 1.6-fold compared to intact rats. In contrast, the hormones pregnant mare serum gonadotropin (PMSG), diethylstilbestrol (DES), and hydrocortisone (HC), administered to hypophysectomized rats, failed to restore PBS density in the adrenal gland. In the kidney, HC administered to hypophysectomized rats caused an increase of 1.4-fold in PBS density compared to untreated hypophysectomized and intact rats. In contrast, the hormones ACTH, PMSG, and DES, administered to hypophysectomized rats, did not affect PBS density in the kidney. None of the hormones tested altered the equilibrium dissociation constant of PBS in either the adrenal gland or the kidney. These findings indicate that PBS density in rat adrenal gland and kidney is hormonally modulated.