心肌自噬在异丙肾上腺素诱导心肌肥厚中的作用

The role of myocardial autophagy in isoproterenol-induced cardiac hypertrophy

目的探讨心肌自噬在异丙肾上腺素(ISO)诱导大鼠心肌肥厚中的作用。方法将29只大鼠随机分为3组:皮下联合腹腔注射生理盐水(Con)组9只、腹腔注射生理盐水联合皮下注射异丙肾上腺(ISO)组10只、腹腔注射雷帕霉素(RAP)联合皮下注射ISO(ISO+RAP)组10只。连续干预14d后,将Con组和ISO组存活大鼠(Con,n=9;ISO,n=8)行心脏超声检查左室壁厚度及左室射血分数(LVEF),再将各组大鼠腹腔注射过量的10%水合氯醛处死,摘除心脏,计算心脏体质量指数(HWI)。心肌组织病理切片行HE染色和Masson染色,Western blot检测p62表达和LC3Ⅱ/Ⅰ比值,透射电镜观察心肌组织自噬泡数量。结果与Con组比较,ISO组左室壁厚度和LVEF明显增加(P<0.01)。与Con组比较,ISO组和ISO+RAP组的HWI增大(P<0.01),且ISO+RAP组的HWI小于ISO组(P<0.01)。与Con组比较,ISO组心肌病理切片显示心肌组织病理性肥厚改变明显;而与ISO组比较,ISO+RAP组心肌组织病理性肥厚明显改善。与Con组比较,ISO组心肌组织LC3Ⅱ/Ⅰ比值下调,而p62表达上调,自噬泡数量明显减少(P<0.05);与ISO组比较,ISO+RAP组心肌组织LC3Ⅱ/Ⅰ比值上调,而p62表达下调,自噬泡数量明显增多(P<0.01)。结论上调心肌自噬活性可以逆转ISO诱导的病理性心肌肥厚。

Objective To explore the effects of myocardial autophagy on isoproterenol (ISO)- induced cardiac pathological hypertrophy in rats. Methods Twenty-nine SD rats were randomly divided into three groups: subcutaneous injection of normal saline combined with intraperitoneal injection of normal saline (Con, n=9) group, subcutaneous injection of normal saline combined with intraperitoneal injection of isoproterenol (ISO, n=10) group and subcutaneous injection of rapamycin (RAP) combined with intraperitoneal injection of ISO (ISO+RAP, n=10) group. After 14-days of continuous treatment, cardiac echocardiogram for left ventricular wall thicknesses and ejection fraction (LVEF) were carried out in Con group (n=9) and ISO group (n=8). Rats were executed by intraperitoneal injection of overdoes 10% chloral hydrate. Heart to body index (HWI) was calculated by heart weight/body weight. Cardiac pathologic alternation was observed by histological sections stained with hematoxylin and eosin (HE) and Masson. The expression of p62 and the ratio of LC3Ⅱ/Ⅰ were measured by Western blot assay. The number of autophagic vacuoles was detected by transmission electron microscopy. Results Compared with Con group, the left ventricular wall thickness and LVEF were significantly increased in ISO group (P<0.01). Compared with Con group, the HWI was increased in ISO group and ISO+RAP group (P<0.01). But the HWI was decreased in ISO+RAP group comparison with that of ISO group (P<0.01). Compared with Con group, the alternation of cardiac pathological hypertrophy was marked in ISO group. Moreover, compared with ISO group, cardiac pathological hypertrophy was improved in ISO+RAP group. Compared with Con group, the ratio of LC3Ⅱ/Ⅰwas down-regulated, the protein expression of p62 was up-regulated and the number of autophagic vesicles was significantly reduced in ISO group (P<0.01). However, compared with ISO group, the ratio of LC3Ⅱ/Ⅰwas up-regulated, the protein expression of p62 was down-regulated and the number of autophagic vesicles was significantly increased in ISO + RAP group (P<0.01). Conclusion The up-regulation of myocardial autophagy can reverse pathological hypertrophy induced by ISO.