目的:通过线粒体质量控制(MQC)探讨茶多酚(TP)对老年2型糖尿病(T2DM)模型大鼠肌肉减少症的改善作用。
方法:将55只2月龄雄性SD大鼠随机分为对照组,老年模型组(老年,n=10)和衰老T2DM模子组(n=35)。老年T2DM模型组大鼠采用高糖高脂饮食喂养,每日腹腔注射50mg/kgD-半乳糖。4周后,老年2型糖尿病模型组大鼠一次性腹腔注射链脲佐菌素(STZ)30mg/kg。STZ注射2周后,将空腹血糖(FBG)≥16.7mmol/L定义为T2DM模型成功。当模型成功诱导时,30只模型大鼠随机分为老年T2DM组,300mg/kgTP治疗组(TP)和3mg/kg罗格列酮治疗组(RSG)根据FBG,每组10只大鼠。每组均给予50mg/kgD-半乳糖诱导衰老,高糖高脂喂养8周。实验结束时采用Westernblot检测模型组腓肠肌组织中P53蛋白的表达,高于对照组,表明老年T2DM模型成功建立。用血糖仪检测FBG,计算腓肠肌相对重量,用透射电镜(TEM)观察腓肠肌线粒体的微观结构,线粒体生物合成相关蛋白PGC-1α的表达,Westernblot检测腓肠肌线粒体动力学相关蛋白(OPA1、DRP1)和线粒体自噬相关蛋白(P62、LC3)。
结果:与对照组相比,Mod组的FBG水平和P53表达均升高(P&lt;0.01)。腓肠肌相对重量,PGC-1α的表达水平,OPA1和LC3II/LC3I比值降低(P<0.01)。P62和DRP1的表达水平显著升高(P<0.01)。线粒体数量减少,体积减少和大量的空泡化,无明显的自噬溶酶体和裂变融合。8周后,与Mod组相比,TP和RSG组腓肠肌线粒体数量,真空化,裂变和聚变得到了改善,自噬溶酶体明显增多。TP组P53、DRP1和P62的表达水平、FBG水平均明显降低(P<0.01,P<0.05)。OPA1和PGC-1α的表达水平,LC3II/LC3I比值和腓肠肌相对重量显著增加(P<0.05,P<0.01)。
结论:TP能改善老年2型糖尿病模型大鼠的肌少症,其机制与线粒体质量调控有关。
OBJECTIVE: To explore whether tea polyphenols(TP) improve sarcopenia in the aged type 2 diabetes(T2DM)model rats via mitochondrial quality control(MQC).
METHODS: A total of 55 2-month-old male SD rats were randomly divided into the control group(n=10), the aged model group(aged, n=10) and the aging T2DM model group(n=35). The aging T2DM model group rats were fed with high-sugar and high-fat diet and intraperitoneally injected with 50 mg/kg D-galactose daily. After 4 weeks, the aging T2DM model group rats were given a single intraperitoneal injection of 30 mg/kg streptozotocin(STZ). After STZ injection for 2 weeks, fasting blood glucose(FBG) ≥ 16.7 mmol/L was defined as successful T2DM model. When the model was successfully induced, the 30 model rats were randomly divided into aged T2DM group(Mod), 300 mg/kg TP teatment group(TP) and 3 mg/kg rosiglitazone treatment group(RSG) according to FBG, with 10 rats in each group. Each group was treated with 50 mg/kg D-galactose to induce senescence and fed with high glucose and fat for 8 weeks. Western blot was used to detect the expression of P53 protein in gastnemius muscle tissue of the model group at the end of the experiment, which was higher than that of the control group, indicating that the aging T2DM model was successfully established. FBG was detected by the blood glucose meter, gastnemius muscle relative weights was calculated, the microstructure of mitochondria of gastnemius muscle was observed by transmission electron microscope(TEM), the expression of mitochondrial biosynthesis-related proteins PGC-1α, mitochondrial dynamics-related proteins(OPA1, DRP1) and mitochondrial autophagy-related proteins(P62, LC3) in gastnemius muscle were detected by western blot.
RESULTS: Compared with the control group, the level of FBG and the expression of P53 in the Mod group were increased(P<0.01). The gastnemius muscle relative weights, the expression level of PGC-1α, OPA1 and the ratio of LC3II/LC3I were decreased(P<0.01). The expression level of P62 and DRP1 were significantly increased(P<0.01). The number of mitochondria decreased, the volume decreased and a large number of vacuolization, and there were no obvious autophagolysosomes and fission and fusion. After 8 weeks, compared with the Mod group, the number of mitochondria in the gastrocnemius of TP and RSG groups, vacuolization, fission and fusion were improved, and the autophagolysosomes was significantly increased. The expression levels of P53, DRP1 and P62, the level of FBG in the TP group were significantly decreased(P<0.01, P<0.05). The expression levels of OPA1 and PGC-1α, the ratios of LC3II/LC3I and gastnemius muscle relative weights were significantly increased(P<0.05, P<0.01).
CONCLUSIONS: TP can improve the sarcopenia in the aged T2DM model rats, and its mechanism is related to the regulation of mitochondrial quality control.