高住低练对大鼠不同类型肌纤维HSP70和VEGF表达的影响

Effects of HSP70 and VEGF of the Original Muscle Fiber Type on Rats in Hypoxia Training

目的:研究模拟不同海拔高度高住低练对大鼠Ⅰ型肌纤维(比目鱼肌)和Ⅱ型肌纤维(腓肠肌)热休克蛋白70(HSP70)和血管生长因子(VEGF)表达的影响。方法:适应性喂养1周后,将48只SD大鼠按体重随机分为6组:常氧对照组(C组)、14.5%O2低氧暴露组(14.5%O2LH组)、12.7%O2低氧暴露组(12.7%O2LH组)、常氧训练组(TL组)、14.5%O2高住低练组(14.5%O2HiLo组)、12.7%O2高住低练组(12.7%O2HiLo组),每组8只。分别采用20.9%、14.5%和12.7%氧浓度的模拟高住低练模型,运动强度逐渐递增,实验共4周。采用免疫组织化学技术检测大鼠腓肠肌和比目鱼肌HSP70和VEGF的定位和半定量表达。结果:(1)与14.5%O2LH组相比,12.7%O2LH组腓肠肌和比目鱼肌HSP70阳性物质表达显著下降(Ρ<0.05,Ρ<0.01),而14.5%O2HiLo组和12.7%O2HiLo两组腓肠肌和比目鱼肌HSP70阳性物质表达与相应的两LH组变化相反;14.5%O2HiLo组腓肠肌HSP70表达显著低于14.5%O2LH组(Ρ<0.05),12.7%O2HiLo组却高于12.7%O2LH组(Ρ<0.05),两个LH组比目鱼肌HSP70表达分别显著高于两个HiLo组(Ρ<0.01)。(2)12.7%O2LH组腓肠肌VEGF阳性物质表达高于14.5%O2LH组(Ρ<0.05),14.5%O2HiLo组和12.7%O2HiLo组两组变化相似,但两HiLo组腓肠肌VEGF表达高于两LH组,氧浓度降低则VEGF表达增加更显著(Ρ<0.01);与C组相比,12.7%O2LH组、TL组和两HiLo组比目鱼肌VEGF阳性物质表达显著增加(Ρ<0.05),比目鱼肌VEGF表达整体趋势类似于腓肠肌。结论:单纯低氧暴露、运动或低氧运动应激/刺激原诱导HSP70和VEGF的表达具有肌纤维类型特异性,单纯低氧暴露比高住低练对HSP70表达的影响明显,而高住低练比单纯低氧暴露、运动对VEGF表达的影响大,Ⅰ型肌纤维(比目鱼肌)中HSP70和VEGF的表达显著高于Ⅱ型肌纤维(白腓肠肌);在Ⅱ型肌纤维中HSP70和VEGF之间存在协同效应,而在Ⅰ型肌纤维中未见。

Objective This paper attempts to study the expression of heat shock protein 70（HSP70） and vascular endothelial growth factor （VEGF）in various muscle fiber types of rats during the simulated hypoxia training at different altitudes. Methods Forty eight SD rats were randomly and equally divided into 6 groups：group C （normoxic control）,group 14.5%O2 LH （14.5%O2 exposure for 22 hours and in normoxic chamber for 2 hours）,group 12.7%O2 LH （12.7%O2 exposure for 22 hours and in normoxic chamber for 2 hours）, group TL （normoxic training）, group 14.5%O2 HiLo （living-high and training-low, staying in 14.5%O2 chamber for 22 hours and in normoxic chamber forl hour,and then normoxic training for another 1 hour）and group 12.7%O2 HiLo （living-high and training-low,staying in 12.7%% 02 chamber for 22 hours and in normoxic chamber for 1 hour,and then normoxic training for another 1 hour）. Incremental exercise was carried out for rats in group TL,group 14.5%O2 HiLo and group 12.7% 02 HiLo for 4 weeks. The expressions of HSPT0 and VEGF in type I muscle fiber （gastrocnemius）and in type II muscle fiber（soleus muscle）were tested with immunohistochemistry. Results 1 ）As compared with group 14.5%O2 LH, the expressions of HSP70 positive material in gastrocnemius decreased （P 〈 0.05）, and in soleus in group 12.7%O2 LH increased significantly （P 〈 0.01）;the expression of HSP70 in gastrocnemius and soleus muscle in groups 14.5%O2 HiLo and 12.7%O2 HiLo changed inversely. HSP70 in gastrocnemius in group 14.5%O2 HiLo was significant lower than in group 14.5%O2LH （P 〈 0.05）. HSP70 in group 12.7%O2 HiLo was higher than in group 12.7%O2 LH（P 〈 0.05）. At the same time,the expression of HSP70 in groups 14.5%O2 LH and 12.7%O2 LH in soleus muscle were significantly higher than in groups 14.5%O2 HiLo and 12.7%O2 HiLo （P 〈 0.01）. 2）The expression of VEGF positive material in gastrocnemius in group LH 12.7%O2 was higher than in group LH 14.5%O2 （P 〈 0.05）, and VEGF positive material in group 14.5%O2 HiLo was also higher than in group 12.7%O2 HiLo. However, the expression of VEGF in gastrocnemius in the two groups of HiLo were higher than in the two groups of LH, and the expression were more significant with increasing of oxygen concentration （P 〈 0.01 ）. Compared with group C, the expression of VEGF positive substances in soleus in the other groups increased significantly （P 〈 0.05）. The expression of VEGF in soleus changed similarly to the gastrocnemius. Conclusion The expressions of HSP70 and VEGF induced by hypoxia,normoxic training or living-high and training-low were highly specified to the muscle fiber types.