KMUP-3防止高糖引起之心肌細胞傷害及改善糖尿病大鼠之心臟功能

KMUP-3 Prevents High Glucose-Induced Cardiomyocytes Injury and Improves Cardiac Functions in Diabetes Rats

洪振庭(Chen-Ting Hung)

指導教授 ： 葉竹來

高雄醫學大學/醫學院/醫學系藥理學科碩士班/碩士(2015年)

摘要

糖尿病心肌病變，常見的併發症有高血壓、高血糖和心室肥厚，這些併發症皆是導致心臟衰竭的主要原因。先前，已有研究報告指出，糖尿病會導致心肌細胞凋亡作用和抑制自噬作用，而細胞自噬和細胞凋亡作用之間的關係在糖尿病心肌病變的發病機制中扮演著重要角色。本實驗最近的研究指出，KMUP-3在心肌細胞中能誘導細胞自噬作用。因此，我們進一步研究KMUP-3是否能夠促使細胞自噬作用產生來預防高血糖引起之心肌損傷並且改善糖尿病大鼠心臟功能。在本篇研究中，取用初生鼠之心肌細胞來模仿高血糖狀態。將心肌細胞培養在葡萄糖濃度為30 mM的細胞培養液中再加入濃度為1到10 M的KMUP-3。糖尿病大鼠動物模式誘導方式為給予65mg/kg劑量的鏈脲佐菌素（Strptozotocin, STZ）進行誘導。KMUP-3則以腹腔注射方式給予1 mg/ kg的劑量。心臟功能評估是由小動物超音波儀器檢測。經由MTT試驗，發現KMUP-3治療能有效減少高糖誘導的心肌細胞死亡。另外，KMUP-3也可以抑制高糖誘導的心肌細胞凋亡，與促細胞存活蛋白Bcl-2的表現量增加，並且降低促細胞凋亡蛋白Bax與cleaved caspase-3的表現量有關。微管相關蛋白I輕鏈3-Ⅱ（LC3-II）是細胞自噬關鍵蛋白。 KMUP-3以時間依賴性明顯增強LC3-II的表現量和促使AMPK蛋白的磷酸化。正如預期，KMUP-3的前處理具劑量依賴性並增強高糖誘導的LC3-II、Atg7和磷酸化AMPK蛋白之表現量。在糖尿病大鼠動物模式中，其縮短分率（FS）、射血分率（EF）及左心室收縮功能的指數明顯下降。跟糖尿病組別相比較，給予KMUP-3的組別其心臟功能指數能有效改善。總而言之，KMUP-3透過誘導細胞自噬作用減少高糖誘導之心肌細胞的細胞凋亡。這些結果顯示，KMUP-3在糖尿病心肌病變的治療中具有巨大的潛力。

關鍵字

細胞自噬 ； 糖尿病大鼠

並列摘要

Diabetes cardiomyopathy, a common disease occurring hypertension, hyperglycemia and ventricle hypertrophy in diabetes patients, is a major complication leads to heart failure. Recently, studies have reported that diabetes induced cardiomyocyte apoptosis and suppressed cardiac autophagy, showing that the relationship between the autophagy and apoptotic cell death pathways plays an important role in the pathogenesis of diabetic cardiomyopathy. Our recent studies indicated that KMUP-3 can induce autophagy in cardiomyocytes. Therefore, we further investigated whether KMUP-3’s promotion of autophagy activity can prevent high glucose (HG)-induce cardiac injury and improve cardiac functions in diabetes mellitus (DM) rats.
In this study, we mimicked hyperglycemia condition in neonatal rat (1-3 day) cardiomyocytes with HG model. Cardiomyocytes were incubated in 30 mM HG in the presence or absence of KMUP-3 (1 to 10 M). An experimental diabetic rat model was induced by 65 mg/kg of streptozoticin (STZ). KMUP-3 was intraperitoneally injected at a dose of 1 mg/kg. Cardiac functions were evaluated by serial echocardiography. We found that KMUP-3 treatment attenuated HG-induced cell death by MTT assay. Additionally, KMUP-3 also inhibited HG-induced apoptosis, with associated increase of Bcl-2 protein, and decrease of Bax protein and caspase-3 cleavage. Microtubule-associated protein I light chain 3-II (LC3-II) is the key protein associated with autophagy. KMUP-3 significantly enhanced production of LC3-II and phosphorylation of AMPK in a time-dependent manner. As expected, KMUP-3 pretreatment dose-dependently reduced the HG-induced decrease of LC3-II, Atg7, and phosphor-AMPK expression. Fractional shortening (FS) and ejection fraction (EF), the index of left ventricular systolic function, were significantly decreased in DM group. Then compared with DM group, these changes were attenuated when diabetic rats were treated with KMUP-3 (P<0.05).
In summary, KMUP-3 attenuates HG-induced cardiomyocytes apoptosis by inducing autophagy. These findings suggest that KMUP-3 may have great therapeutic potential in the treatment of diabetic cardiomyopathy.

並列關鍵字

Autophagy ； Diabetes mellitus rats

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