膳食补充亮氨酸可通过抑制泛素-蛋白酶体削弱增龄小鼠骨骼肌萎缩

发布时间：2019-06-07 07:59

【摘要】：目的:探讨膳食补充亮氨酸对增龄所致骨骼肌萎缩的影响及可能机制。方法:13月龄雄性ICR小鼠根据体重随机分为补充亮氨酸(Leu)、补充丙氨酸(Ala)以及空白对照组(NC),Leu和Ala组分别在饲料中添加5%比例亮氨酸和3.4%比例丙氨酸8周,NC组饲喂普通饲料。末次给食后禁食17h处死小鼠,便携式血糖仪检测血糖;ELISA法检测血清胰岛素、IGF-1;分光光度法检测血尿素氮;氨基酸分析仪检测血浆游离氨基酸谱;HE染色观察肌纤维适应性及病理性改变;BCA法定量蛋白后,Western Blotting法检测Ub、Atrogin-1、MuRF-1及MHCⅡ的蛋白表达。结果:与NC组和Ala组小鼠相比,添加5%亮氨酸(Leu组)未显著影响小鼠体重、采食量,血糖、胰岛素水平与IGF-1无显著变化,血尿素氮水平显著下降;血浆游离亮氨酸含量升高而丙氨酸、甘氨酸和谷氨酸含量下降;腓肠白肌湿重/体重比值、肌纤维横截面积及直径均表现出增长的趋势,但增幅并不显著;骨骼肌纤维圆形化、核中心化病变显著减少;腓肠白肌总蛋白含量、MHCⅡ蛋白表达显著增加,而Ub、Atrogin-1及MuRF-1的蛋白表达均显著下降。Ala组与NC组小鼠相比各指标差异均无统计学意义。结论:亮氨酸能够削弱老年前期小鼠骨骼肌萎缩,其机制可能与亮氨酸对泛素-蛋白酶体系统的抑制有关。
[Abstract]:Objective: to investigate the effect of dietary Leucine supplementation on skeletal muscle atrophy induced by aging and its possible mechanism. Methods: 13 month old male ICR mice were randomly divided into Leucine (Leu), supplemented with alanine (Ala) and blank control group (NC), according to body weight. Leu and Ala groups were fed with 5% Leucine and 3.4% alanine respectively for 8 weeks, and NC group was fed with common feed. The mice were killed after fasting for 17 hours after the last administration, blood glucose was measured by portable blood glucose meter, serum insulin was detected by ELISA, blood urea nitrogen was detected by IGF-1; spectrophotometry, and plasma free amino acid spectrum was detected by amino acid analyzer. The adaptability and pathological changes of muscle fibers were observed by HE staining, and the protein expression of Ub,Atrogin-1,MuRF-1 and MHCII was detected by, Western Blotting after quantitative protein by BCA. Results: compared with NC group and Ala group, adding 5% Leucine (Leu group) had no significant effect on body weight, feed intake, blood glucose, insulin level and IGF-1, but blood urea nitrogen level decreased significantly. The content of plasma free Leucine increased while the contents of alanine, glycine and glutamic acid decreased, the wet weight / body weight ratio of sural white muscle, the cross section area and diameter of muscle fiber increased, but the increase was not significant. The fibers of skeletal muscle were circular and the lesions of nucleus centralization were significantly reduced. The total protein content of sural white muscle and the expression of MuRF-1 II protein increased significantly, while the protein expression of Ub,Atrogin-1 and MuRF-1 decreased significantly. There was no significant difference between Ala group and NC group. Conclusion: Leucine can weaken skeletal muscle atrophy in presenile mice, and its mechanism may be related to the inhibition of ubiquitin proteasome system by Leucine.
【作者单位】：井冈山大学体育学院;武汉体育学院研究生院;北京体育大学运动人体科学学院;成都体育学院;成都大学体育学院;保山学院体育学院;
【基金】：江西省科技厅自然科学基金青年项目(20142BAB215048) 四川省教育厅自然科学科研项目(13ZB0073)
【分类号】：R151.45

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