第一型糖尿病(Type 1 diabetes mellitus，Type 1 DM)高血糖誘發的惡病質會增加肌肉蛋白質異化作用，造成骨骼肌肉萎縮。先前文獻證實，疾病相關惡病質造成的骨骼肌肉萎縮與增加泛素-蛋白酶體途徑 （Ubiquitin-proteasome pathway，UPP）、自噬作用-溶酶體途徑（Autophagy-lysosome pathway，ALP）有密切關係。草莓葉富含高含量維生素C及多酚、類黃酮、單寧等植化素。過去研究證實，草莓葉萃取物可以改善心血管疾病、癌症及糖尿病腎病變。本實驗目的為評估草莓葉水萃物對改善高血糖所造成的肌肉萎縮之功效。C57BL/6J小鼠於實驗第一週餵食高脂飲食兩週後，第三週利用streptozotocin（STZ，50 mg/kg）腹腔注射，連續五天，待一週後小鼠血糖值大於200 mg/dl則於實驗第五週灌食小鼠滅菌水或草莓葉水萃物（500 mg/kg）每週三次，連續兩週後犧牲。研究結果顯示，相較於糖尿病高血糖小鼠，補充草莓葉水萃物可抑制紅血球及血漿MDA與Tumor necrosis factor alpha濃度，增加腓腸肌內Superoxide dismutase 2、Catalase及GSH reductase與Nuclear factor erythroid-2-related factor蛋白質表現量，減少p38 Mitogen-activated protein kinase (p38MAPK)磷酸化及Myostatin (Mstn)表現。餵食草莓葉水萃物也可降低糖尿病高血糖小鼠腓腸肌Atrogin 1/MAFbx、Muscle RING finger protein 1、Ubiquitination與Microtubule-associated protein 1A/1B-light chain 3表現外，並減少轉錄因子Forkhead transcription factor 1 (FoxO1)、Nuclear factor-kappa B (NF-κB)、Signal transducer and activator of transcription 3 (STAT3)及CCAAT/enhancer binding protein-δ (C/EBP-δ)核蛋白質表現，與延緩Myosin heavy chain (MyHC)蛋白質流失。綜合以上可知補充草莓葉水萃物可透過減少p38 MAPK、Mstn及ROS與促發炎物質，使FoxO1、NF-κB、STAT3及C/EBP-δ無法進入細胞核，降低UPP及ALP相關分子表現，同時提高抗氧化酵素蛋白的表現，減少體內發炎反應並改善糖尿病惡病質引起的肌肉萎縮。
Hyperglycemia of Type 1 diabetes mellitus（type 1 DM）induced cachexia can increase protein catabolism and cause skeletal muscle atrophy. Previous studied show cachexia related disease intensify skeletal muscle protein catabolism by up-regulation of ubiquitin-proteasome pathway and autophagy-lysosome pathway which play an important role in cachexia induced muscle atrophy. Strawberry leaves are rich in vitamin C and phytochemicals, such as polyphenol, flavonoid, tannic. Previous studies have showed that strawberry leaf extracts have therapeutic values in treatments of cardiovascular diseases, cancer and diabetic nephropathy. In the present study we assessed the inhibitory effect of strawberry leaf extract on skeletal muscle atrophy induced by DM cachexia. C57BL/6J mice were fed with high fat diet（HFD）in Experiment first week and the third week injected with streptozotocin（STZ,50 mg/kg）continued five days to induced hyperglycemia and then mice were fed with water or strawberry leaf aqueous extract（500 mg/kg）three times a week, continuous period for two weeks than sacrificed. Compare with DM mice, supplementation with strawberry leaf aqueous extract not olny inhibited the concentration of tumor necrosis factor alpha and MDA in blood and phosphoylated p38 Mitogen-activated protein kinases (p38MAPK) and myostatin (mstn)expression in gastrocnemius but also increase the expression of antioxidant enzymes such as superoxide dismutase 2、catalase、GSH reductase and nuclear Nrf2 protein in gastrocnemius. Moreover, supplementation with strawberry leaf aqueous extract decrease diabetic cachexia-induced expression of Atrogin-1/MAFbx、Muscle RING finger protein 1、Ubiquitination and Microtubule-associated protein 1A/1B-light chain 3 protein expression as well as Forkhead transcription factor 1 (FoxO1), Nucler factor-kappa B,Signal transducer (NFκB), activator of transcription 3 (STAT3) and CCAAT/enhancer binding protein-δ nuclear protein (C/EBP-δ)and myosin heavy chain (MyHC) protein depletion. The data suggested that strawberry leaf aqueous extract supplementation could via decrease p38 MAPK、mstn ROS and proinflammatory cytokines to blocked FoxO1、NF-κB、STAT3 and C/EBP-δ into muclear, reduce UPP and ALP related molecules expressed ,in addition enhance antioxidant enzymes expressed, reduce inflammation and useful for improveing the muscle atrophy in diabetic cachexia.
