CAJ | 학술논문

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。
목적：탐토선식보충량안산대증령소치골격기위축적영향급가능궤제。방법：13월령웅성ICR소서근거체중수궤분위보충량안산（Leu）、보충병안산（Ala）이급공백대조조（NC）,Leu화Ala조분별재사료중첨가5%비례량안산화3.4%비례병안산8주,NC조사위보통사료。말차급식후금식17h처사소서,편휴식혈당의검측혈당;ELISA법검측혈청이도소、IGF-1;분광광도법검측혈뇨소담;안기산분석의검측혈장유리안기산보;HE염색관찰기섬유괄응성급병이성개변;BCA법정량단백후,Western Blotting법검측Ub、Atrogin-1、MuRF-1급MHCⅡ적단백표체。결과：여NC조화Ala조소서상비,첨가5%량안산（Leu조）미현저영향소서체중、채식량,혈당、이도소수평여IGF-1무현저변화,혈뇨소담수평현저하강;혈장유리량안산함량승고이병안산、감안산화곡안산함량하강;비장백기습중/체중비치、기섬유횡절면적급직경균표현출증장적추세,단증폭병불현저;골격기섬유원형화、핵중심화병변현저감소;비장백기총단백함량、MHCⅡ단백표체현저증가,이Ub、Atrogin-1급MuRF-1적단백표체균현저하강。Ala조여NC조소서상비각지표차이균무통계학의의。결론：량안산능구삭약노년전기소서골격기위축,기궤제가능여량안산대범소-단백매체계통적억제유관。
Objective： To investigate the effect of leucine supplementation on muscle atrophy induced by ageing and preliminarily analyzes the possible mechanism. Methods： Thirteen-month- old male ICR mice were randomly divided into dietary leucine supplementation （ Leu）, alanine supplementation （Ala） and normal control group （NC） by body weight. Mice in leucine （Leu） and alanine （Ala） supplementation group were treated with normal chow diet supplemented with 5 % leucine and 3.4 % alanine respectively for 8 weeks, while normal control group were fed with normal diet. Seventeen hours of fasting after the last feeding, mice were sacrificed. The blood glucose was determined with a portable blood glucose meter. The level of BUN was detected by using spectrophotometry. The profile of plasma free amino acids was detected with an amino acids analyzer. The serum insulin and IGF-1 concentration were determined by ELISA. The skeletal muscle morphology was observed by using hematoxylin and eosin staining. The protein expression of Ub, Atrogin-1, MuRF-1 as well as MHC Ⅱ was detected by the method of Western blotting after BCA protein assay. Results：Compared with both NC and Ala group, the results showed that, leucine supplementation （Leu） did not change the level of body weight, food intake, blood glucose, serum insulin and IGF-1, while the level of BUN was significantly elevated;The content of plasma leucine was increased, content of alanine, glutamic acid and glycine were all depressed significantly. Although the wet ratio of wet white gastrocnemius muscle to body weight, cross-sectional area and diameter of fibers were not influenced significantly by leucine supplementation, still showed a tendency to increase. The incidence of rounded and central nucleus fibers was reduced. Moreover, total protein content, the protein expression of MHC Ⅱ were both elevated, while the expression of Uh, Atrogin-1 and MuRF-1 in white gastrocnemius muscle were significantly depressed. There weren＇t statistically significant differences of all parameters between mice in NC and Ala group. Conclusion.. Leucine supplementation significantly attenuates skeletal muscle atrophy in pre-senile mice, which may be correlated with inhibiting the activity of ubiquitin-proteasome system.