姜黄素和亮氨酸对免疫应激大鼠骨骼肌蛋白质降解的缓解效应

EFFECTS OF CURCUMIN AND LEUCINE ON SKELETAL MUSCLE PROTEOLYSIS IN RATS EXPOSED TO IMMUNE CHALLENGE

目的探索姜黄素和亮氨酸对免疫应激大鼠骨骼肌蛋白质降解的缓解效应及可能机制。方法体质量190~220g的SD大鼠40只,按体质量相近原则均分为正常、应激、姜黄素添加（1.5%姜黄素）、亮氨酸添加（3%亮氨酸）和联合添加（1.5%姜黄素＋3%亮氨酸）共5组。除正常组外,其余4组均通过腹腔注射LPS 50μg/kg诱导免疫应激,大鼠饲喂3w后宰杀取样。结果免疫应激导致大鼠生长速度降低,肝急性期蛋白、血清白细胞数量和炎性因子IL-1含量显著上升（P〈0.05）,日粮添加姜黄素可缓解上述负面效应;免疫应激导致大鼠骨骼肌肌纤维密度和直径减小,蛋白质降解速率显著增加,添加姜黄素和亮氨酸均能显著抑制肌肉蛋白质降解（P〈0.05）,且显著下调NF-κB和泛素连接酶基因MAFbx和Mu RF1表达水平（P〈0.05）。结论姜黄素和亮氨酸均能通过抑制炎性因子分泌及泛素-蛋白酶体关键分子表达,缓解免疫应激大鼠骨骼肌蛋白质降解。

Objective To evaluate the effects of curcumin and leucine on lipopolysaccharide（LPS）-induced skeletal muscle atrophy in rats. Methods Forty male mice were divided into five groups： control（Con）, LPS-challenged（LPS）, Curcumin-diet group（1.5% Cur）, leucine- diet group（3% Leu）, co- diet group（CL）. Rats in control group were injected with saline, and others were injected with LPS（50 μg/kg）. Results Compared with the controls, LPS challenge decreased body weight gain, and significantly elevated concentrations of serum IL-1, and hepatic acute phase protein（P〈0.05）. Additionally, LPS-challenge significantly increased the muscle protein degradation rate, resulting in decreased density and diameter of muscle fibers（P〈0.05）. However, these negative effects of LPS were alleviated by 3 week dietary curcumin and leucine supplementation. The dietary supplementation also down-regulated NF-κB, MAFbx and Mu RF1 expressions in the muscle（P〈0.05）. Conclusion Both curcumin and leucine can alleviate LPS-induced skeletal muscle degradation through down-regulation of cytokine secretion and protein degradation in rats.