模拟不同海拔高住低练对大鼠心肌VEGF和HSP70的影响

Effects of Simulated Living High-Training Low on the Myocardial VEGF and HSP70 of Rats

目的:探讨模拟不同海拔高住低练对大鼠心肌保护性蛋白热休克蛋白70(HSP70)和血管内皮生长因子(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)、14.5%O2低氧暴露组(14.5%O2LH)、12.7%O2低氧暴露组(12.7O2LH)、常氧训练组(TL)、14.5%O2高住低练组(14.5%O2LiLo)、12.7%O2高住低练组(12.7%O2HiLo),每组8只。采用20.9%、14.5%和12.7%三种氧浓度暴露和运动强度逐渐递增的高住低练模型,两LH组每天在低压氧舱中放置22 h后2 h舱外常氧生活,两HiLo组每天在低压氧舱中放置22 h后常氧生活1 h,再常氧训练1 h,所有进行低氧暴露的动物每周实验6天;TL组和两HiLo组进行一次5～10 min跑台适应性训练(速度为16 m/min,坡度为0)后,每天训练速度为35m/min,运动时间从30 min至60 min递增,每3天增加5 min,每天训练1次,每周6天,共4周。实验方案结束后24 h,麻醉大鼠取大鼠心尖肌组织,采用免疫组织化学技术检测VEGF和HSP70表达。结果:(1)与C组比较,14.5%O2LH组、TL组和12.7%O2的HiLo组VEGF阳性物质表达量显著增加(Ρ<0.05),12.7%O2LH组增加不显著(Ρ>0.05),而14.5%O2HiLo组表达量增加非常显著(Ρ<0.01);14.5%O2LH组VEGF阳性物质表达量较12.7%O2LH组显著增加(Ρ<0.05),12.7%O2HiLo组比14.5%O2HiLo组显著降低(Ρ<0.05),14.5%O2HiLo组VEGF阳性物质表达量较14.5%O2LH组显著增加(Ρ<0.05)。(2)与C组相比较,14.5%O2LH组、14.5%O2和12.7%O2两HiLo组HSP70阳性物质表达量增加(Ρ<0.05),12.7%O2LH组表达最明显,而TL组增加不显著(Ρ>0.05);14.5%O2LH和HiLo两组HSP70阳性物质表达量分别比12.7%O2LH和HiLo两组显著降低(Ρ<0.05),而两LH组HSP70阳性物质表达量分别与两HiLo组相比无显著性差异(Ρ>0.05)。结论:单纯低氧暴露、常氧运动及高住低练三种应激因素均诱导细胞保护性蛋白VEGF和HSP70表达;14.5%O2HiLo组的VEGF表达最显著,而12.7%O2LH组的HSP70表达最显著。

Objective In this paper, we study the expression of myocardial vascular endothelialgrowth factor （VEGF） and heat shock protein 70 （HSP70） of the rats under the simulated hypoxictraining at different altitudes. Methods Forty eight SD rats were randomly and equally divided into 6 groups： group C （normoxic control） , group 14.5%O2LH （ 14.5%O2 exposure for 22 hours and 2 hours in normoxic chamber） , group 12.7%O2LH （ 12.7% 02 exposure for 22 hours and 2 hours in nor- moxic chamber） , group TL （normoxic training） , group 14.5%O2HiLo （14.5%O2 living-high andtraining-low, staying in 14.5%O2 chamber for 22 hours and 1 hour in normoxic chamber, and then nor- moxic training for another 1 hour） and group 12.7%O2HiLo （ 12.7%O2 living-high and training-low, staying in 12.7%%O2 chamber for 22 hours and 1 hour in normoxic chamber, and then normoxic train- ing for another 1 hour） . All animals were exposed to hypoxia 6 days a week. Group TL, and groups14.5%O2HiLo and 12.7%O2HiLo started training on a treadmill for 5- 10 min （ 16m/min, 0° slope） , then increased the duration 10 min per day till 60 rain at the speed of 35 m/min, six days per week for a total of 4 weeks. The apical ventricle was taken for determination of the expression of HSP70 andVEGF 24 hours after the completion of the experiment. Results （ 1 ） The expression of VEGF-positive material in group 14.5%O2LH, group TL and group 12.7%O2 HiLo increased more significantly than in group C （P 〈 0.05） , especially in group 14.5%O2HiLo （P 〈 0.01 ） , and remained unchanged in group 12.7% O2LH （P 〉 0.05 ） . As compared to group 12.7%O2LH, the expression of VEGF-positivematerial in group 14.5%O2LH increased significantly （P 〈 0.05）, and in group 12.7%O2HiLo was sig- nificantly lower than in group 14.5%O2HiLo （P 〈 0.05 ） . The expression of VEGF-positive material in group 14.5% O2HiLo increased more significantly than in group 14.5%O2LH （P 〈 0.05） . （2） As compared with group C, the expression of HSP70-positive material increased in groups 14.5%O2LH,12.7%O2 and 14.5%O2HiLo （P 〈 0.05） , especially in group 12.7%O2LH, while in group TL in- creased insignificantly （P 〉 0.05） . The expression of HSP70-positive material in groups 14.5%O2LH and 14.5%O2HiLo was respectively lower than in groups 12.7%O2LH and 12.7%O2HiLo （P 〈 0.05） . However, the expression of HSP70-positive material were no significantly different from respectivegroups of LH and HiLo （P 〉 0.05 ） . Conclusion All of the hypoxic exposure, normoxic exercise, and HiLo could induce the increases in the expressions of VEGF and HSP70; the VEGF in group 4.5%O2HiLo and HSP70 in group 12.7%O2LH were expressed most significantly.