17β-雌二醇和2-甲氧基雌二醇对慢性低氧性肺动脉高压大鼠体内内皮素-1/一氧化氮体系的影响

Effects of 17 β-estradiol and 2-methoxyestradiol on Endothelin-1/Nitric Oxide Cascade in Experimental Rats With Hypoxic Pulmonary Hypertension

目的:探讨17β-雌二醇(E2)及2-甲氧基雌二醇(2ME)对慢性低氧性肺动脉高压大鼠体内内皮素-1(ET-1)/一氧化氮(NO)体系的影响。方法:雌性SD大鼠48只,按随机数字表法平均分为6组(各组n=8):假手术组、去势组、低氧组、去势+低氧组、去势+低氧+E2组、去势+低氧+2ME组。去势组行卵巢切除术;非去势组打开腹腔找到卵巢后不做处理直接还纳缝合。术后去势+低氧+E2组皮下注射E2[20μg/(kg·d)],去势+低氧+2ME组皮下注射2ME[240μg/(kg·d)],其他组皮下注射生理盐水(0.1 ml/d)。低氧组大鼠置于低氧箱内饲养,非低氧组大鼠呼吸正常空气。连续饲养8周以建立低氧性肺动脉高压模型。分别测定血清ET-1、NO水平、内皮型一氧化氮合酶(eNOS)活性及肺组织内皮素A受体(ET_AR)、内皮素B受体(ET_BR)、eNOS表达变化。结果:低氧组、去势+低氧组大鼠肺小动脉管壁增厚,管腔变窄明显,平均肺动脉压(mPAP)显著高于假手术组(P均<0.01);E2和2ME干预组大鼠上述形态学及mPAP改变相对较轻。与假手术组相比,去势组和低氧组血清ET-1和肺组织ET_AR mRNA及蛋白水平均明显升高,ET_BR mRNA及蛋白水平明显下降(P均<0.01);去势+低氧组以上指标变化更显著;E2和2ME干预后血清ET-1和肺组织ET_AR表达明显下降,但仍高于假手术组,同时ET_BR表达明显上升,但仍低于假手术组(P均<0.01);且去势+低氧+2ME组血清ET-1水平低于去势+低氧+E2组(P<0.05)。与假手术组相比,去势组肺组织eNOS蛋白水平明显下降(P<0.01);低氧组血清NO水平及肺组织eNOS蛋白水平明显下降(P<0.05或P<0.01);去势+低氧组血清NO水平、eNOS活性及肺组织eNOS mRNA和蛋白水平均明显下降(P均<0.01);去势+低氧+E2组和去势+低氧+2ME组上述指标较去势+低氧组均明显上升(P<0.05或P<0.01),但仍低于假手术组(P均<0.05)。结论:E2及2ME均能显著降低血清ET-1水平,减少肺组织ET_AR表达,增加ET_BR的表达,升高血清NO水平、eNOS活性及肺组织eNOS表达,通过改善ET-1/NO体系平衡部分逆转肺动脉高压。

Objective： To explore the effects of 17 β-estradiol（E2） and 2-methoxyestradiol（2ME） on endothelium-1/nitric oxide（ET-1/NO） cascade in experimental rats with hypoxic pulmonary hypertension. Methods： A total of 48 female SD rats were randomly divided into 6 groups：① Sham operation group,② Ovariectomy（OVX） group,③ Hypoxia group,④ OVX＋hypoxia group,⑤ OVX＋hypoxia＋E2 group, the rats received subcutaneous E2 at 20μg/（kg·d） and⑥ OVX＋hypoxia＋2ME group, the rats received subcutaneous 2ME at 240μg/（kg·d）. n=8 in each group. Blood levels of ET-1, NO, eNOS activity and the expressions of pulmonary tissue endothelium A receptor（ETAR）, ETBR and eNOS were compared among different groups.Results： Compared with Sham operation group, Hypoxia and OVX＋hypoxia groups showed small pulmonary artery thickening with lumen narrowing, increased mean pulmonary arterial pressure（mPAP）, all P〈0.01; the above morphological and m PAP changes were reduced by E2 and 2ME intervention. Compared with Sham operation group, OVX and Hypoxia groups had increased blood ET-1 and pulmonary mRNA, protein expressions of ETAR, decreased pulmonary ETBR, all P〈0.01; the above changes were more obvious in OVX＋hypoxia group; E2 and 2ME intervention reduced blood ET-1 and pulmonary ETAR expression, but they were still higher than Sham operation group, meanwhile, ETBR expression was elevated, but it was still lower than Sham operation group, all P〈0.01; blood ET-1 was lower in OVX＋hypoxia＋2ME group than OVX＋hypoxia＋E2 group, P〈0.05. Compared with Sham operation group, OVX group had decreased pulmonary eNOS protein expression, P〈0.01; Hypoxia group had decreased blood NO and pulmonary e NOS protein expression, P〈0.05 or P〈0.01; OVX＋hypoxia group had decreased blood NO, e NOS activity and decreased pulmonary mRNA and protein expressions of eNOS, all P〈0.01; E2 and 2ME intervention elevated the above indexes, P〈0.05 or P〈0.01, but they were still lower than Sham operation group, all P〈0.05.Conclusion： E2 and 2ME could decrease blood ET-1 and pulmonary ETAR expression, increase pulmonary ETBR expression; elevate blood NO, eNOS activity and pulmonary eNOS expression. E2 and 2ME may partially reverse pulmonary hypertension via improving ET-1/NO cascade in experimental rats.