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

摘要

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2h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 (NFκB) 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 phisphop38MAPK 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 phisphoNF-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.