Effect of estrogen on cardiovascular responses to psychological stress in rats

据报道，雌激素具有心血管保护作用，但这些作用的机制尚未明确。我们研究了自由活动大鼠应激诱导的心血管反应的性别差异以及雌激素对这些反应的影响。此外，我们评估了雌激素对促肾上腺皮质激素释放激素（CRH）在应激诱导的心血管反应中的作用。实验采用雄性大鼠(M)、正常雌性大鼠（NF）、去卵巢+安慰剂组(P)和去卵巢+雌激素组(E)四组。换笼应激诱导心理应激。将大鼠置于新环境后，血压和心率显著升高。与M组相比，NF组血压升高明显降低。卵巢切除术降低了血压对应激反应的性别差异。1 .与第1天相比，M组在每天重复60 min的换笼应激过程中，第2天和第3天的血压升高明显减弱，而NF组则没有。与P组相比，E组在换笼和约束应激时血压反应明显受到抑制。2 . E组小鼠血浆去甲肾上腺素应激反应明显减弱。非应激NF组、P组和E组大鼠脑室内注射CRF-41 （10 μg）可使血压和心率升高。但3组间差异无统计学意义。体外注射CRH-41受体拮抗剂a-螺旋CRH（9-41）对三组雌性大鼠应激性高血压均无减轻作用。这些结果表明雌激素可能通过抑制雌性大鼠交感神经张力的激活来影响应激时的血压调节。NF组和E组对这些应力具有更强抵抗力的机制有待进一步研究。少

Estrogens are reported to have cardiovascular protective effects, but the mechanisms underlying these effects are not well defined. We investigated the sex difference in stress-induced cardiovascular responses and the effect of estrogen on these responses in free-moving adult rats. Furthermore, we assessed the central role of estrogen on the effect of corticotrophin-releasing hormone (CRH) in stress-induced cardiovascular responses.Four groups of rats, which consisted of male (M), normal female (NF), ovariectomized+placebo-treated (P) and ovariectomized+estrogen-treated (E) groups, were used in this experiment.1. Psychological stress was induced by cage-switch stress. After rats were placed in the novel environment, blood pressure and heart rate significantly increased. Blood pressure elevation was attenuated significantly in the NF group compared with the M group. Ovariectomy diminished the sex difference of blood pressure response to the stress.2. In the M group blood pressure elevat … More ion during cage-switch stress, which was repeated 60 min daily, was weakened on the 2nd and the 3rd days compared with the 1st day, but not in the NF group.2. The blood pressure responses were suppressed significantly in the E group compared with the P group during cage-switch and restraint stress. The plasma norepinephrine response induced by cage-switch stress was attenuated significantly in the E group.3. In unstressed NF, P and E group rats, the intracerebroventricular (I.C.V.) injection of CRF-41 (10 μg) increased blood pressure and heart rate. However, there were no significant differences between 3 groups.4. The I.C.V.injection of a-helical CRH (9-41), a CRH-41 receptor antagonist, did not attenuated the stress-induced hypertension in the 3 groups of female rats.These results suggest that estrogen may influence blood pressure regulation during stress in suppressing the activation of a sympathetic nervous tone in female rat. The mechanisms responsible for the greater resistance to these stresses in the NF and E group should be investigated further. Less