雌激素对低氧性肺动脉高压大鼠体内血管紧张素转换酶-血管紧张素Ⅱ-血管紧张素受体-1轴的影响

Effects of estrogen on ACE-AngⅡ-AT1 axis in ovariectomy and hypoxic pulmonary hypertensionrats

目的：探讨雌激素对低氧性肺动脉高压大鼠体内血管紧张素转换酶-血管紧张素Ⅱ-血管紧张素受体-1（ ACE-AngⅡ-AT1）轴的影响。方法将60只健康雌性SD大鼠按随机数字表法随机平分为6组：假手术组、单纯去势组、单纯低氧组、去势＋低氧组、去势＋雌激素组、去势＋低氧＋雌激素组。假手术组打开腹腔找到双侧卵巢后不做处理直接还纳缝合，单纯去势组行切除卵巢术，单纯低氧组持续低氧（24 h，8周），去势＋低氧组切除卵巢后持续低氧，去势＋雌激素组切除卵巢后每天给予雌激素20μg＆#183; kg -1皮下注射，去势＋低氧＋雌激素组切除卵巢后每天给予雌激素并且持续低氧。连续饲养8周，以建立低氧肺动脉高压模型。测量平均肺动脉压（ mPAP）后放血处死大鼠，观察右心室肥厚指数（ RVHI）、HE染色观察肺小动脉重塑情况。用放射免疫法、紫外分光光度法、Western印迹法、反转录PCR测定AngⅡ、ACE、AT1水平。结果单纯低氧组和去势＋低氧组大鼠肺小动脉管壁增厚管腔变窄明显， mPAP、RVHI 分别为（32.4＆#177;2.2） mmHg （1 mmHg ＝0.133 kPa ）、0.331＆#177;0.032和（37.9＆#177;1.6） mmHg、0.433＆#177;0.033，均显著高于假手术组的（12.6＆#177;1.8） mmHg、0.233＆#177;0.029（均P＜0.05）；去势＋低氧＋雌激素组上述改变较轻，mPAP[（26.1＆#177;1.4）mmHg]显著高于假手术组（P＜0.05），而RVHI （0.267＆#177;0.040）与假手术组差异无统计学意义（P＞0.05）。 ACE、AngⅡ、AT1表达水平在单纯去势组、单纯低氧组、去势＋低氧组均升高，且均显著高于假手术组（均P＜0.05），而去势＋雌激素组、去势＋低氧＋雌激素组上述指标表达水平变化不明显（均P＞0.05）。结论雌激素对低氧性肺动脉高压的干预作用可能部分是通过下调肺组织ACE和AT1受体的表达从而降低ACE-AngⅡ-AT1轴活性实现的。

Objective To explore the effects of estrogen （E2） on angiotensin converting enzymeangiotensin Ⅱ-angiotensin type 1 receptor （ACE-Aug Ⅱ-AT1 ） axis in hypoxie pulmonary hypertension rats. Methods A total of 60 healthy female Sprague-Dawdley （SD） rats were divided randomly into 6 groups （n = 10 each） of sham operation,pure ovariectomy （OVX） ,pure hypoxia, OVX ＋ hypoxia, OVX ＋ E2 and OVX ＋ hypoxia ＋ E2. Abdominal cavity was opened for sham operation group and bilateral ovaries were left intact without any other procedure. The pure OVX group underwent oophorectomy. The pure hypoxia group were placed into a low-oxygen environment （24 hour,8 weeks）. The OVX ＋ hypoxia group were placed into a low-oxygen environment after bilateral oophorectomy. The OVX ＋ E2 group received a subcutaneous injection of E2 （20 μg · kg^-1·d^-1 ） after bilateral oophoreetomy. The OVX ＋ hypoxia ＋ E2 group had an injection of E2 and was placed into a low-oxygen environment after bilateral oophoreetomy. The rats were feed continuously for 8 weeks to establish hypoxic pulmonary hypertension model. The mean pulmonary artery pressure （mPAP） was measured after bloodletting. Then right ventricle hypertrophy index （RVHI） andhematoxylin-eosin pulmonary artery remodeling （HPSR） were observed. And electron microscope was employed to observe pulmonary arteriolar ultrastructure. The methods of radio-immunity assay, ultraviolet spectroscopy, Western blot and reverse transcription PCR were used to measure the levels of CE, Ang U and AT1 in sera,lung and pulmonary artery. Results The vascular walls of pure hypoxia and OVX ＋ hypoxia groups became thickened and lumen narrowed, mPAP and RVHI were （ 32.4 ± 2. 2） mmHg （ 1 mmHg = 0. 133 kPa） ,0. 331 ±0. 032 and （37.9 ±1.6） mmHg,0. 433 ±0. 033. Both were significantly higher than those of Sham operation group （（12.6 ± 1.8） mmHg, 0.233 ±0.029） （both P 〈0.05）; the above parameters of OVX ＋ Hypoxia ＋ E2 group changed little. And mPAP （（ 26. 1 ±1. 4 ） mmHg ） was significantly higher than that in sham operation group （ P 〈 0.05 ） while the difference in RVHI between OVX ＋ Hypoxia ＋ E2 （0. 267 ± 0. 040） and sham operation groups had no statistical significance （ P 〉 0. 05）. Compared with Sham operation group, the expression levels of ACE, Ang Ⅱ and AT1 in pure OVX, pure hypoxia and OVX ＋ hypoxia groups rose markedly （ all P 〈 0. 05 ）. However, the OVX ＋ E2 and OVX ＋ hypoxia ＋ E2 groups had no obvious change （ all P 〉 0. 05）. Conclusion The intervention effect of E2 for hypoxic pulmonary hypertension may be partly mediated by the down-regulated expressions of ACE and AT1 in lung tissue resulting in the reduced activity of ACE-Ang Ⅱ -AT1 axis.