Development of Hypertension in Spontaneously Hypertensive Rats after Gonadectomy

Abstract
Male spontaneously hypertensive rats (SHR) were gonadectomized at an age of 5 weeks. Systolic blood pressure and heart rate were measured up till an age of 12 weeks in trained unanesthetized rats. The development of the hypertension and heart rate were not significantly affected by removal of the testes and epididymis or removal of the testes only. Kidney, adrenal and thymus weight did differ from the values in sham-operated rats. After the administration of secobarbital sodium, however, a significant lower blood pressure had been observed in gonadectomized rats compared with sham-operated rats. Significantly higher levels of secobarbital were detected in plasma and brain of gonadectomized SHR. It is concluded that gonadectomy does not effect blood pressure of SHR and that the previously reported retardation of development of hypertension in gonadectomized SHR is caused by the different effect of anesthesia on blood pressure of gonadectomized and sham-operated rats.