Estradiol replacement attenuates stress‐induced pressor response by regulating renin‐angiotensin system in ovariectomized rats

Abstract

We examined whether chronic estrogen replacement has suppressive effects on psychological stress‐induced pressor response by attenuating renin‐angiotensin system (RAS) in ovariectomized rats. Female Wistar rats aged 9 wk were ovariectomized. After 4 wk, the rats were assigned either to a placebo‐treated (Pla) group or a group treated with 17β‐estradiol (E2) subcutaneously implanted with either pellet. Two wk later, they were implanted with radiotelemetry devices for blood pressure (BP) and heart rate (HR) measurements, and the half of them were denervated renally. These rats underwent cage‐switch stress 2 wk after the operation. The stress elevated the BP and HR rapidly and continuously both in the Pla and E2 groups. However, these responses to the stress were attenuated significantly in the E2 group compared with the Pla group. An angiotensin II type 1 receptor blocker, losartan, abolished the difference in the BP response to the stress between the two groups. In addition, the stress induced elevation of plasma renin activity and angiotensin II concentration only in the Pla group, but not in the E2 group. Furthermore, the renal sympathetic nerve denervation attenuated the pressor response in the Pla group. These results suggest that estradiol replacement attenuates psychological stress‐induced pressor response by suppressing RAS activation in ovariectomized rats.