姜黄素对糖尿病大鼠心肌自噬,凋亡及AMPK-mTOR信号通路的影响

目的:基于心脏组织AMPK/mTOR信号通路、自噬和凋亡来探讨姜黄素(curcumin，Cur)对糖尿病大鼠心脏损伤的保护作用。方法:50只雄性SD大鼠被随机分为3组:正常对照组(Con，n=10)给予正常饮食以及等量生理盐水腹腔注射;糖尿病模型组(DM，n=40)大鼠给予高糖高脂饮食联合连续5 d腹腔注射链脲佐菌素(streptozocin，STZ) (35 mg·kg^-1·d^-1)，给药组(Cur+DM)，部分糖尿病大鼠(n=20)在其饮用水中给予Cur(300 mg·kg^-1·d^-1)进行干预16周。HE染色观察大鼠心脏组织形态改变;透射电镜观察大鼠心脏组织粒体形态变化;TUNEL染色，免疫组织化学和蛋白印迹等方法检测心脏组织自噬、凋亡，AMPK/mTOR信号通路等相关蛋白的表达情况。结果:与正常对照组相比，糖尿病模型组大鼠心肌肥大，线粒体嵴稀疏、断裂，自噬及相关蛋白表达水平下降(P<0.05)，细胞凋亡及相关蛋白表达水平显著增加(P<0.05)，P-AMPK/AMPK蛋白表达水平降低(P<0.05)而P-mTOR/mTOR增加(P<0.05)。与糖尿病模型组比较，给药组大鼠心肌肥大水平和线粒体断裂程度减轻，自噬及相关蛋白表达水平增加(P<0.05)，细胞凋亡及相关蛋白表达水平减轻(P<0.05)，P-AMPK/AMPK蛋白表达水平增加(P<0.05)，而P-mTOR/mTOR减少(P<0.05)。结论:姜黄素可能通过活化AMPK/mTOR信号通路增强糖尿病大鼠心脏组织自噬水平，减轻心脏组织细胞凋亡，从而改善糖尿病大鼠心脏损伤。

Effects of curcumin on autophagy,apoptosis and AMPK/mTOR signaling pathway in the heart of diabetic rats

OBJECTIVE To investigate the protective effects of curcumin (Cur) on the cardiac injury of diabetic rats based to AMPK/mTOR signaling pathway,autophagy and apoptotic cell death.METHODS 50 male Sprague Dawley (SD) rats were randomly divided into 3 groups:normal control group (Con group) were fed with normal diet and ip injected with equivalent volume of citrate buffer,diabetic model group (DM group) were fed with high fat diet for 4 weeks before receiving intraperitoneal (ip) injections of Streptozocin (STZ,35 mg·kg^-1) for five consecutive days,and partial diabetic rats,which were orally administrated with Cur (300 mg·kg^-1·d^-1) for 16 weeks,served as administrated group (DM+Cur group). Histopathological changes of heart tissues were observed by hematoxylin-eosin (HE) staining and Transmission electron microscopy (TEM) were used to evaluate the pathological changes of mitochondria in the hearts tissues of rats; TdT-mediated dUTP nick end labeling (TUNEL) staining was used to measure cell apoptosis,immunohistochemistry (IHC) and western blot were used to detect the protein expression.RESULTS Compared with Con group,the levels of myocardial hypertrophy and apoptosis were increased (P<0.05),the mitochondrial cristae were sparse and fractured,the level of autophagy was decreased (P<0.05),the protein expression of P-AMPK/AMPK decreased (P<0.05),while P-mTOR/mTOR increased (P<0.05) in DM group. After the intervention of Cur,compared with DM group,the levels of myocardial hypertrophy,apoptosis and mitochondrial rupture were alleviated (P<0.05) in myocardial tissue,the phosphorylation of AMPK was increased (P<0.05),while mTOR decreased (P<0.05).CONCLUSION Cur may trigger autophagy to alleviate apoptosis in the heart tissues of diabetic rats through activating AMPK/mTOR signaling pathway,and ameliorate diabetic cardiomyopathy.