低肌糖原含量促进运动诱导大鼠骨骼肌IL-6基因转录的可能信号通路

Low Muscle Glycogen Facilitates the Signal Pathway of Exercise-induced IL-6 Gene Transcription in Skeletal Muscle of Rats

目的:探讨低肌糖原含量促进运动诱导的骨骼肌白细胞介素6(interleukin-6,IL-6)基因转录的增加与核转录因子κB(Nuclear factor kappa B,NF-κB)及p38丝裂原激活的蛋白激酶(Mitogen-activated protein kinase,p38MAPK)信号通路激活的关系。方法:空白对照组(n=8)大鼠不运动,其余80只大鼠分为正常肌糖原组和低肌糖原组两大组,每组40只,先进行2 h跑台运动(消耗肌糖原),运动后24 h内采取不同膳食干预,低肌糖原组大鼠运动后6 h喂食低糖饲料,正常肌糖原组运动后即刻喂食标准饲料,这样运动24 h后低肌糖原组大鼠肌糖原含量与空白对照组相比显著降低(P<0.05),而正常肌糖原组大鼠肌糖原含量与空白对照组相比无显著性差异(P>0.05)。然后两个大组进行定量负荷运动,分别于运动前、运动30 min即刻、运动2 h即刻、运动2 h后恢复3 h和恢复6 h宰杀大鼠取材,测定血清IL-6蛋白含量、肌糖原含量、骨骼肌NF-κB及p38MAPK蛋白含量和骨骼肌IL-6 mRNA水平。结果:与运动前相比,低肌糖原组和正常肌糖原组大鼠运动2h即刻骨骼肌IL-6 mRNA水平、骨骼肌核磷酸化NF-κB蛋白含量、骨骼肌核磷酸化p38MAPK蛋白含量均显著上升(P<0.05)。与运动2 h即刻相比,低肌糖原组与正常肌糖原组运动后3 h及运动后6 h骨骼肌IL-6 mRNA水平增加,骨骼肌核磷酸化p38MAPK蛋白含量下降,而骨骼肌核磷酸化NF-κB蛋白含量运动后3 h上升,运动6 h后下降。运动2 h即刻、运动2 h后3 h及运动2 h后6 h,低肌糖原组与正常肌糖原组上述三指标均有显著性差异(P<0.05)。结论:低肌糖原含量促进运动引起的骨骼肌IL-6基因转录增加可能是通过激活NF-κB和p38MAPK信号通路实现的。

Objective The purpose of the study was to investigate the relation of exercise-induced facilitation of interleukin-6（IL-6）gene transcription to the activation of nuclear factor kappa B（NF-κB）and mitogen p38MAPK signal pathway.Methods Rats in blank control group（n = 8）did not exercise,and the other 80 rats underwent 2-hour exercise to deplete the glycogen in skeletal muscle,and then were divided into low glycogen group（fed with low carbohydrates 6 hours after the exercise）and normal glycogen group（fed with standard forage 6 hours after the exercise）.As a result,the content of muscle glycogen in low glycogen group was significantly lower than that in the blank control group（P 0.05）24 hours after the exercise,while the content of muscle glycogen in normal glycogen group was not significantly different from that in the blank control group（P 0.05）.Finally,the rats in normal glycogen group and low glycogen group performed an exercise with fixed load.All rats were slaughtered in batch before exercise,immediately after 30-minute and 2-hour exercise,and 3 hours and 6 hours after the 2-hour exercise.The levels of serum IL-6,skeletal muscle glycogen,NF-κB,p38MAPK and the expression level of IL-6 mRNA were determined.Results The level of IL-6 mRNA and the content of nuclear phospho-NF-κB and phospho-p38MAPK in the skeletal muscle in low glycogen group and normal glycogen group elevated significantly（P 0.05）2 hours after exercise.The level of IL-6 mRNA in low glycogen group and normal glycogen group increased,nuclear phispho-p38MAPK decreased 3 hours and 6 hours after 2-hour exercise as compared with that immediately after the exercise,whereas the nuclear phispho-NF-κB increased 3 hours after 2-hour exercise and decreased 6 hours after the exercise.The level of IL-6 mRNA,nuclear phispho-p38MAPK and nuclear phispho-NF-κB immediately after 2-hour exercise,and 3 and 6 hours after the exercise revealed significant differences between low glycogen group and normal glycogen group（P 0.05）.Conclusion The decreased low muscle glycogen stimulated exercise-induced IL-6 gene transcription possibly through the activation of NF-κB and p38MAPK signal pathway.