Sex hormones change adrenoceptors in blood vessels of the spontaneously hypertensive rat.

In this study we investigated how male sex hormones, which increase blood pressure in the spontaneously hypertensive rat (SHR), affect adrenergic receptors in the cardiovascular system. Testosterone treatment significantly increased blood pressure in male SHRs (P < 0.05). Testosterone treated male SHRs also showed a significant increase (P < 0.05) in total apparent numbers of alpha 1 adrenoceptors in tail artery preparations as compared to controls. Gonadectomy attenuated blood pressure and caused a decrease in the total apparent number of alpha 1 adrenoceptors in tail artery preparations (P < 0.05). Testosterone replacement therapy in these gonadectomized rats reversed this decrease in apparent number of alpha 1 adrenoceptors to control values. KD values for dihydroalprenolol, isoproterenol, prazosin and norepinephrine were not significantly different between treatment groups. These results indicate that sex hormones (androgens) modulate numbers of alpha 1 adrenoceptors in the cardiovascular system of the male SHR.