Estrogen Replacement Suppresses Pressor Response and Oxidative Stress Induced by Cage-switch Stress in Ovariectomized Rats

We examined the suppressive effects of estradiol on psychological stress–induced cardiovascular responses and oxidative stress in ovariectomized rats, both placebo‐treated (OVX+Pla) and estrogen‐treated (OVX+E2). The elevations in blood pressure and heart rate induced by cage‐switch stress were attenuated in the OVX+E2 as compared with the OVX+Pla group. NG‐nitro‐L‐arginine methyl ester, administered via drinking water, reduced the difference in these responses. Furthermore, this stress increased plasma nitrotyrosine and decreased plasma nitric oxide (NO) metabolites only in the OVX+Pla group. We demonstrated that estrogen replacement suppresses cardiovascular responses to psychological stress, at least in part by improving NO bioavailability in ovariectomized rats.