长期大负荷训练大鼠不同类型骨骼肌HSP72表达

目的:训练和修复失衡导致了过度训练,近来研究表明,热休克蛋白72(HSP72)可能是较适合的过度训练监测指标,鉴此,本研究利用过度训练动物模型对其可行性进行初步探讨.方法:36只雄性2月龄SD大鼠被随机分成4组:对照组(n=4)和3个力竭性游泳训练组(n=8).训练组大鼠在第1、2周适应性游泳30min至2h,在第3周至第8周进行力竭性游泳训练.分别取第6、7、8周血样,测定血红蛋白、血清睾酮、血清皮质醇和血清肌酸激酶的浓度;取同侧比目鱼肌、腓肠肌红肌和腓肠肌白肌测定HSP72蛋白含量.结果:(1)过度训练常规指标的变化:4至6周力竭性游泳训练导致大鼠运动能力下降,安静时血红蛋白、血清睾酮和皮质醇浓度下降,肌酸激酶浓度增加,表明过度训练动物模型建立.(2)HSP72表达变化:与对照组HSP72表达(100%)相比,训练组第6、7、8周比目鱼肌HSP72表达分别减少2.6%、6.6%、33%;腓肠肌红肌HSP72表达显著增加(P<0.05),分别较对照组增加133%、214%、157%;腓肠肌白肌HSP72表达显著增加(P<0.001),分别较对照组增加410%、790%、1030%.三种类型骨骼肌HSP72表达的净增量均在第6周最高,随后逐周下降.HSP72表达变化早于激素浓度的变化.结论:长期超负荷训练导致的骨骼肌HSP72表达变化早于过度训练综合征.应激激素变化滞后于HSP72表达变化,提示骨骼肌HSP72表达变化可能关联着过度训练的外周机制,可以考虑骨骼肌HSP72作为过度训练的监测指标.

Prolonged Strenuous Exercise-induced HSP72 Expression in Skeletal Muscle of Rats

Objective This study was aimed to investigate the feasibility of heat shock protein (HSP72) for monitoring overtraining on animal module. Methods Thirty-six Sprague-Dawley male rats (2-month old) were assigned to either a sedentary control group (4 rats per group, 3 groups in total) or an exhaustive swimming group (8 rats per group, 3 groups in total). Rats swam 30 min to 2 hours per day in the 1st and 2nd week (wk) (6 days per wk), and swam to exhaustion in 3rd wk and 8th wk (once a day, 6 days per wk). In 6th wk, 7th wk, 8th wk, blood samples were collected separately to determine the concentrations of hemoglobin (Hb), serum creatine kinase (CK), serum testosterone (ST), the serum cortisol (SCort); Relative levels of HSP72 in the soleus (SOL), the red gastrocnemius muscle (RG), and the white gastrocnemius muscle (WG) were determined. Results (1) Four to six weeks exhaustive swimming resulted in significant decrease in performance and in Hb, ST, SCort levels and significant increase in CK level in all exercised rats. (2) In 6th wk, 7th wk, 8th wk, HSP72 levels in the soleus of trained groups decreased 2.6%, 6.6%, 33%, respectively; whereas in the red gastronemius increased 133%, 214%, 157%, respectively (P< 0.05);and in the white gastronemius increased 410%, 790%, 1030%, respectively (P< 0.001), as compared with that in sedentary control groups (100%). Maximal net increase in HSP72 levels of three types of skeletal muscle appeared in 6th wk, thereafter gradually decreased. The change in HSP72 levels was prior to the alteration of stress hormone levels. Conclusions These findings revealed that decreased HSP72 levels in skeletal muscle with prolonged strenuous exercise was prior to occurrence of overtraining syndrome.The change in stress hormonal levels lagged the alteration of HSP72 levels, and decrease in HSP72 levels may lead to alteration of stress hormonal levels. Change in HSP72 levels could be associated with peripheral mechanisms of overtraining, suggesting that HSP72 could act as a marker for monitoring overtraining.