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，但这些作用背后的机制尚未很好地确定。我们研究了应激诱导的心血管反应的性别差异以及雌激素对自由活动成年大鼠这些反应的影响。此外，我们还评估了雌激素在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中枢作用。本实验使用了四组大鼠，包括雄性(M)、正常雌性(NF)、去卵巢+安慰剂治疗(P)和去卵巢+雌激素治疗(E)组。笼式开关应激可诱发心理应激。将大鼠置于新的环境中后，血压和心率显著增加。与M组相比，NF组的血压升高明显减轻。结论：1.卵巢切除降低了血压对应激反应的性别差异。在M组中，血压升高…结果：1.笼式转换应激时，每天重复60min的离子在第2、3天较第1天有所减弱，但与第1天相比无明显差异。E组在笼式转换和束缚应激时的血压反应明显低于P组。E组大鼠血浆去甲肾上腺素反应明显减弱。在非应激组，大鼠的脑室内(I.C.V.)注射促肾上腺皮质激素释放因子-41(10μg)可增加血压和心率。但3组间差异无统计学意义。侧脑室注射CRH-41受体拮抗剂α-螺旋CRH(9-41)不能减轻3组雌性大鼠的应激性高血压。这些结果表明，雌激素可能通过抑制交感神经张力的激活而影响应激过程中的血压调节。NF组和E组对这些应力有更大的抵抗力的机制有待进一步研究。较少

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