黄芪甲苷通过诱导自噬减轻慢性间歇性低氧大鼠心脏损伤

目的 探讨黄芪甲苷（ASⅣ）对慢性间歇性缺氧（CIH）大鼠的心肌保护作用和机制。 方法 SD雄性大鼠24只，随机分为对照组、CIH组、CIH+ASⅣ组和ASⅣ组，每组6只。CIH大鼠循环给予氮气和氧气，使氧气含量在9%～21%间循环，每个循环3 min，每天上舱8 h，共35 d。CIH+ASⅣ组和ASⅣ组每天给予黄芪甲苷干预，对照组和CIH组采用等量生理盐水灌胃。超声心动图检测大鼠心脏左心室功能；HE染色和麦胚芽凝集素染色检测左心室心肌结构；TUNEL检测心肌细胞凋亡；比色法检测心肌组织匀浆的超氧化物歧化酶（SOD）活性和丙二醛(MDA)含量；Western blotting检测凋亡相关蛋白Bcl-2、Bax和自噬相关蛋白LC3、Beclin1、P62及哺乳动物雷帕霉素靶蛋白（mTOR）的表达水平。 结果 与对照组相比，CIH模型组大鼠左室射血分数（LVEF）及左心室收缩末期内径（LVIDs）降低，心肌纤维排列紊乱，心肌细胞增大，心肌细胞凋亡率增加，Bcl-2/Bax比率下降，SOD活性降低，MDA含量增加，Beclin1表达下降而P62表达上升，p-mTOR/mTOR比率升高。与CIH组相比，ASⅣ干预使LVEF和LVIDs上升，心肌纤维排列较整齐，心肌细胞无异常增大，心肌细胞凋亡率下降，Bcl-2/Bax比率增高，SOD活性增加，MDA水平下降，LC3 Ⅱ/Ⅰ比率增高，Beclin1表达增高而P62表达下降，p-mTOR/mTOR比率下降。 结论 ASⅣ可能通过抑制mTOR诱导自噬，从而减轻CIH间歇性低氧对大鼠心脏的损伤。

Astragaloside Ⅳ alleviating chronic intermittent hypoxia-induced cardiac injury by enhancing autophagy

Objective To investigate the protective effects of astragaloside Ⅳ（ASⅣ）on chronic intermittent hypoxia (CIH)-induced cardiac injury. Methods Twenty-four male adult Sprague Dawley rats were randomly assigned to control, CIH, CIH+ASⅣ, and ASⅣ group, 6 rats in each group. Circular nitrogen and oxygen were filled to make oxygen concentration change between 9%-21% for the CIH treated rats. The exposure cycle was repeated every 3 minutes, 8 hours/day for 35 days. ASⅣ was given by intragastric administration daily before intermittent hypoxia exposure in the CIH+ASⅣ group and ASⅣ group. The control group and CIH group were given normal saline of the same quantity. Echocardiography was used to analyse cardiac function. Myocardial structure was assessed by HE and wheat germ agglutinin staining. The apoptosis of cardiomyocytes was detected by TUNEL assay. The levels of superoxide dismutase (SOD) and malondialdehyde (MDA) in heart were detected by commercial kits. Western blotting was used to evaluate the levels of Bcl-2, Bax, LC3, Beclin1, P62, and mammalian target of rapamycin（mTOR）. Results In the CIH group, the left ventricular ejection fraction (LVEF) and left ventricular internal diameter at end-systole (LVIDs) were inhibited, the myocyte cells showed disordered arranged, enlarged diameters and higher apoptosis rate. The MDA content was significantly elevated and the SOD activity decreased in CIH group when compared with those of control. What’s more, the expression level of Beclin 1 decreased while the P62 expression and the p-mTOR/mTOR ratio increased in the CIH group. Compared with the model group, the LVEF, LVIDs, SOD activity, LC3Ⅱ/Ⅰ ratio, and Beclin1 expression of rats in the CIH+ASⅣ group increased. The cardiomyocytes in the rats of CIH+ASⅣ group showed normal arrangement and diameters. The apoptosis rate, MDA content, P62 expression and the p-mTOR/mTOR ratio decreased in the CIH+ASⅣ group when compared with the CIH group. Conclusion ASⅣ can alleviate CIH-induced cardiac injury by promoting autophagy via mTOR.