Effect of gonadectomy on the development of diabetes mellitus, hypertension, and albuminuria in the rat model.

Spontaneously hypertensive rats (SHR) given streptozotocin (STZ) neonatally developed genetic hypertension and overt hyperglycemia after the onset of puberty. In the present study, gonadectomy was performed before puberty in both males and females of this animal model. Orchidectomy suppressed the development of hypertension in vehicle-treated and STZ-treated SHR (systolic blood pressure at 11 weeks of age: 209 +/- 5 mm Hg in the intact vehicle group v 187 +/- 6 mm Hg in the orchidectomized vehicle group, P < .01; 211 +/- 14 mm Hg in the intact STZ group v 182 +/- 4 mm Hg in the orchidectomized STZ group, P < .001). Furthermore, orchidectomy ameliorated the development of overt hyperglycemia in STZ-treated SHR (nonfasting plasma glucose at 12 weeks of age: 22.1 +/- 0.7 mmol/L in the intact group v 16.1 +/- 2.4 mmol/L in the orchidectomized group, P < .05). On the other hand, orchidectomy did not affect glucose tolerance in vehicle-treated SHR, but attenuated the insulin response to an oral glucose load (P < .05). Orchidectomy significantly decreased urinary albumin excretion and kidney weight in both the vehicle and the STZ groups. Ovariectomy significantly increased body weight gain irrespective of STZ treatment. However, ovariectomy had no effect on hypertension, hyperglycemia, albuminuria, or kidney weight in either vehicle or STZ groups. This study demonstrated that gonadectomy had protective effects against development of hypertension, hyperglycemia, and albuminuria in males but not in females. This suggests that sex hormones may be important as a link between diabetes mellitus and hypertension in males.