Menopause Induced by Oophorectomy Reveals a Role of Ovarian Estrogen on the Maintenance of Pressure Homeostasis

Objectives: Following spontaneous menopause women show a greater increase in systolic and diastolic blood pressure than men of the same age. The aim of the present study was to assess the effect of acute ovarian hormone withdrawal and replacement on blood pressure and forearm blood flow.

Methods: We studied 18 fertile middle-aged normotensive women (48 +/- 1.5 years, range 46-51 years) 1 week prior and 1 month subsequent to bilateral oophorectomy by means of 24-h blood pressure monitoring and strain-gauge venous occlusion plethysmography. Eighteen subjects who had undergone hysterectomy with ovarian sparing, matched for age and biophysical characteristics, were used as a control group. All women were free from cardiovascular risk factors or disease.

Results: Oophorectomy increased the mean values of 24 h (P < 0.001), daytime (P < 0.05), and nighttime (P < 0.01) diastolic blood pressure and nighttime systolic blood pressure (P < 0.01). Blood pressure increase was associated with a rise in forearm vascular resistance (P < 0.01). No significant changes in either blood pressure or forearm vascular resistance values were observed in hysterectomized women. In 16 oophorectomized women a 3-month estrogen replacement therapy (ERT) (17beta-estradiol, 100 mcg/day by transdermal patches) brought blood pressure and forearm vascular resistance values to a level comparable to that recorded before intervention.

Conclusions: Surgically-induced menopause causes an increase in peripheral vascular resistance and blood pressure suggesting a role of ovarian hormones in the homeostatic pressure modulation. Recovery of the baseline condition after ERT suggests that the accelerated increase in blood pressure after menopause is due to ovarian and above all estrogen insufficiency.