不同时间离心运动对大鼠比目鱼肌和趾长伸肌损伤的影响及炎性机制研究

Effects of different amounts of eccentric exercise on soleus and extensor digitorum longus muscle injury in rats and its inflammatory mechanism

目的通过不同时间的离心运动,复制大鼠骨骼肌损伤模型,观察不同离心运动时间对大鼠比目鱼肌和趾长伸肌的炎性基因表达水平的影响。方法雄性Wister大鼠随机分为3组:安静对照组(A组)、一次离心运动损伤组(1T组)、一周离心运动损伤组(1 W组),每组8只。采用动物跑台运动,下坡跑(离心运动),跑台坡度-16°。1 W组先进行1周适应性训练,再进行1周正式训练。1T组进行1周适应性训练,再进行一次大强度离心运动。最后一次训练结束后24 h,所有大鼠过夜禁食12 h后,称重,腹腔麻醉,取材。结果与A组相比,1T组和1W组大鼠血清CK、LDH水平均显著升高(P<0.05或P<0.01);1 W组大鼠血清CK、LDH水平显著低于1T组(P<0.05或P<0.01)。A组大鼠的比目鱼肌和趾长伸肌TLR4 mRNA、MyD88 mRNA、NF-κB mRNA、NLRP3 mRNA、TNF-αmRNA、IL-1βmRNA表达水平无差异(P>0.05),比目鱼肌中毛细血管数量多于趾长伸肌。1T组大鼠比目鱼肌TLR4 mRNA、MyD88 mRNA、NF-κB mRNA、NLRP3 mRNA、TNF-αmRNA、IL-1βmRNA表达水平显著高于A组大鼠比目鱼肌(P<0.01),比目鱼肌细胞间有稍许炎症浸润,细胞间间隙增大;1T组大鼠的趾长伸肌TLR4 mRNA、IL-1βmRNA表达水平显著高于A组大鼠的趾长伸肌(P<0.01),1T组大鼠的趾长伸肌MyD88 mRNA、NF-κB mRNA、NLRP3 mRNA表达显著低于1T组大鼠的比目鱼肌(P<0.01)。1 W组大鼠的比目鱼肌TLR4 mRNA、MyD88mRNA、NLRP3 mRNA表达水平显著高于A组大鼠的比目鱼肌(P<0.01),TLR4 mRNA表达水平显著低于1T组大鼠的比目鱼肌(P<0.05);1 W组大鼠的趾长伸肌TLR4 mRNA表达水平显著高于A组大鼠的趾长伸肌(P<0.01),MyD88 mRNA、NLRP3 mRNA表达水平显著低于1 W组大鼠的比目鱼肌(P<0.01);与A组相比,1T组大鼠的比目鱼肌和趾长伸肌的显微结构变化不大。结论一次离心运动和一周离心运动对大鼠骨骼肌均造成了一定程度的损伤与炎症,这可能与离心运动激活了骨骼肌TLR4/MyD88相关信号通路有关;与一周离心运动相比,一次大强度离心运动对大鼠骨骼肌造成的损伤更严重,炎症因子的表达水平更高,且大鼠比目鱼肌的损伤程度比趾长伸肌更大。

Objective To establish a skeletal muscle injury rat model using different amounts of eccentric exercise,and to observe the effects of the model on the expression of inflammatory genes in soleus and extensor digitorum longus muscles.Methods Male Wister rats were randomly divided into three groups:quiet control group(group A),onetime centrifugal exercise injury group(1 Tgroup),and one-week centrifugal exercise injury group(1 W group).The rats used the animal treadmill to run downhill(centrifugal movement),and the gradient of the treadmill was-16°.The 1 W group first received one week of adaptive training followed by one week of formal training.One week of adaptive training was given to the 1 T group followed by one session of intensive centrifugal exercise.Twenty-four hours after the last training,all rats were fasted overnight for 12 hours,then weighed,anesthetized and sampled.Results Compared with group A,the serum creatine kinase and lactate dehydrogenase levels of rats in the 1 T and 1 W groups were significantly higher(P<0.05 or P<0.01)and the serum CK and LDH levels of rats in the 1 W group were significantly lower than those in the 1 T group(P<0.05 or P<0.01).There was no difference in mRNA levels of TLR4,MyD88,NF-κB,NLRP3,TNF-α,or IL-1βbetween soleus and extensor digitorum longus muscles in group A(P>0.05).The number of capillaries in the soleus was greater than that in the extensor digitorum longus in group A.The mRNA levels of TLR4,MyD88,NF-κB,NLRP3,TNF-αand IL-1βin the soleus of the 1 T group were significantly higher than those in the soleus of group A(P<0.01).There was a small amount of inflammatory cell infiltration between the soleus muscle cells,and the intercellular space was increased.The mRNA levels of TLR4 and IL-1βin the extensor digitorum longus in the 1 T group were significantly higher than those in group A(P<0.01),and the mRNA levels of MyD88,NF-κB and NLRP3 in the extensor digitorum longus were significantly lower than those in the soleus in the 1 T group(P<0.01).The mRNA levels of TLR4,MyD88 and NLRP3 in the soleus of the 1 T group were significantly higher than those of group A(P<0.01),and the level of TLR4 mRNA was significantly lower than that of the 1 T group(P<0.05).The level of TLR4 mRNA in the extensor digitorum longus in the 1 W group was significantly higher than that in group A(P<0.01),and the mRNA levels of My D88 and NLRP3 were significantly lower than those in the soleus in the 1 W group(P<0.01).The microstructure of soleus and extensor digitorum longus muscles in the 1 W group was little changed.Conclusions One-time eccentric exercise and one week eccentric exercise can cause a certain degree of injury and inflammation in skeletal muscle of rats,which may be related to the activation of TLR4/My D88-related signaling stimulated by eccentric exercise.Compared with one week of centrifugation,one time high-intensity centrifugation caused more serious damage to skeletal muscle and higher expression of inflammatory factors.The degree of injury in the soleus of rats was greater than that in the extensor digitorum longus.