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. N(G)-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.