Influence of physiologic oscillation of estrogens on cerebral hemodynamics

The interactions between estrogens and the cerebrovascular system are complex and not fully understood. There are evidences suggesting that the hormones confer protection against cerebral ischemia. Our aim in this study was to investigate the effects of physiological variations of estradiol plasmatic concentration on cerebral hemodynamics. We investigated cerebrovascular reactivity to hypercapnia with transcranial Doppler ultrasonography and the breath-holding index method in the right middle cerebral artery of 20 young women during the menstrual and the ovulatory phase. Data were compared with those of 20 men matched for age. The mean value of the breath-holding index was significantly higher (p<0.001) in females during the ovulatory phase than in the menstrual phase. In men, values were similar to those of women during the menstrual phase. These results suggest that estrogens influence the adaptation capacity of the cerebrovascular system. The possible pathophysiological implications of the relationships between sex hormones and cerebral hemodynamics deserve further investigation.