Inhibition of the development of spontaneous hypertension in SH rats by gonadectomy or estradiol.

Young male and female rats that become spontaneously hypertensive when they mature were gonadectomized at 30 days of age while they were still normotensive. Gonadectomy retarded the usual steep ascent of blood pressure up to 120 days of age. Ovariectomized females "escaped" from this inhibiting effect, and blood pressure rose to severely high levels, i.e., 210 mm Hg, from 150 to 240 days. Treatment with testosterone or estradiol demonstrated that estradiol was particularly effective in inhibiting the usual rise in blood pressure in intact (sham-operated) or gonadectomized males and females. Although effectively lowering blood pressure, estradiol also caused increased pituitary and adrenal weights, hyperlipidemia, and increased circulating levels of corticosterone and DOC.