The effect of estrogen on blood pressure regulation during psychological stress and its mechanism

(1)雌激素通过内皮型一氧化氮合酶(ENOS)的过度表达减弱心理应激诱导的大鼠升压反应。遥测系统显示，在自由活动的大鼠中，雌性(F)组比雄性(M)组对笼式转换应激的升压反应有抑制趋势。此外，与安慰剂治疗组(P)相比，去卵巢雌激素治疗(E)组大鼠对笼子转换和束缚应激的反应显著减弱。但预先给予一氧化氮合酶抑制剂后，应激性升压反应在P组和E组之间的差异缩小。E组肠系膜eNOS表达明显高于M组和P组。这些结果表明，雌激素可以减弱心理应激诱导的大鼠升压反应，肠系膜eNOS的过度表达可以解释其作用机制。(2)女性月经周期对精神应激的升压反应取决于血浆雌二醇水平。年轻女性月经周期(M)和排卵前(O)的静息血压(BP)没有差异。颜色词测试(CWT)引起的收缩压(SBP)和舒张压(DBF)升高在O期较M期略有升高，但未见明显减弱。此外，静息血浆去甲肾上腺素(NE)在O期升高，CWT引起的升高在O期趋于减弱。此外，绝经后妇女(PM)的静息DBF高于YW。在CWT期间，PM组的DBP显著高于YW组，并持续到恢复期的约15分钟。这些发现表明，雌激素可能会减弱由精神压力引起的女性DBP升高。

We obtained the following results on the effect of estrogen on stress-induced pressor responses and its mechanism.(1)Estrogen attenuates pressor responses induced by psychological stresses through endothelial nitric oxide synthase(eNOS) overexpression in rats.Pressor response to the cage-switch stress tended to be suppressed in the female (F) group compared with the male (M) group in free moving rats using the telemetry system. Furthermore, these responses to the cage-switch and restraint stresses were attenuated significantly in the ovariectomized estrogen-treated (E) group compared with the placebo-treated (P) group. However, pretreatment of NOS inhibitor diminished the difference of the stress-induced pressor response between the P and E groups. Moreover, the expression of eNOS in the mesentery enhanced significantly in the E group compared with the M and P groups. These results suggest that estrogen attenuates psychological stress-induced pressor responses and the mesenteric eNOS overexpression could explain the mechanism for its effect in rats.(2)Pressor response to mental stress varies during menstrual cycle depending on plasma estradiol levels in women.The resting blood pressure(BP) was not different between the menstrual (M) and the pre-ovulatory (O) phases of menstrual cycle in young women(YW). The elevations of systolic BP(SBP) and diastolic BP(DBF) induced by the Color Word Test(CWT) were slightly, but not significantly attenuated in O-phase compared with M-phase. In addition, the resting plasma norepinephrine(NE) was higher in O-phase, and its CWT-induced elevation tended to be attenuated in O-phase. Furthermore, the resting DBF was higher in postmenopausal women(PM) than YW. The significant and immediate elevation of DBP during the CWT was greater in PM than in YW and continued until about 15 min of the recovery period. These findings suggest that estrogen may attenuate the DBP elevations induced by the mental stress in women.