| Heat shock proteins ,instrinsic protecting proteins, are considered to play an essential role in protecting cells or organism from stress and preparing them to survive disturbed environment. HSP70 overexpression induced by heat stress can provide thermotolerance. This induced cellular adaptions which enable the cells or organism to better deal with futher exercise challenge. Previous studies have demonstrated that one bout of exercise is able to increase HSP70 content which depending on exercise intensity and time.The purpose of this study was to observe the HSP70 change of after an acute exercise, and HSP70 change postexercise after previous hyperthermic treatment. At the same time we examined the changes of superoxide dismutase (SOD), Malonldehyde (MDA),nitrous oxide (NO),Blood lactic acid (BLA) and analyzed protection of HSP70 overexpression induced by hyperthermic pretreatment.Adult (3 months old ) SD rats were divided into eight groups: normothermic sedentary (Norm sed) ,normothermic exercise Oh (Norm Exe Oh), normothermic exercise 3h(Norm Exe 3h), normothermic exercise24h (Norm Exe 24h),heat stress sedentary (Heat Sed), heat stress exercise Oh (Heat Exe Oh), heat stress exercise 3h (Heat Exe 3h), heat stress exercise 24h (Heat Exe 24h).The rats were heated until the rectal temperature reached 42℃ for 15 min.Then the rats of Heat Sed were at rest under the normal temperature for 24h. Norm sed and Heat Sed were killed immediately, Norm Exe and Heat Exe ran on a treadmill for one hour . The rats were killed at Oh, 3h, 24h after exercise, quadriceps femories were sampled to analyze HSP70,SOD,MDA,NO. Blood was sampled immediately for BLA after exercise.The results were as follows:(1) HSP70 expression increased significantly at 24h after hyperthermic pretreatment.It is conclude that HSP70 overexpression can be induced by heat stress.(2) HSP70 content remained unchanged immediately postexercise for Norm sed, compared with Norm sed,HSP70 content increased significantly immediately, postexercise in Heat Sed, After 3h,HSP70 content both increased significantly and it returned to the basal level at 24h,but the Heat Sed is still higher than Norm sed, We concluded that HSP70 can express more easely after heat stress.(3) SOD activity in quadriceps femories elevated significantly immediately after an acute exercise. Its activity decreased after 3h and returned the basal level at 24h. There were significant difference between Norm sed and Heat Sed. It is conclude that HSP70 overexpression induced by hyperthermic treatment is able to enhance SOD activity in quadriceps femories. MDA content increased immediately postexercise. Its content decreased after 3h and returned the basal level at 24h. Compared with Norm sed , the MDA is eliminated more easily in Heat Sed. We concluded that HSP70 is probably involved in eliminating free radicals.(4) Heat stress and exercise can accumulate the expression of HSP70 which improve the tolerance of organism further.(5) There was significant change of NO content in quadriceps femories at 24h after heat stress. This demonstrated NO can be induced by hyperthermic pretreatment. We found NO content increased significantly immediately and increased respectively from rest at 3h after exercise. It returned the basal level at 24h. Compared with HSP70, trend is similar. This result demonstrates that NO may play an essential role in inducing HSP70.
|
PDF Full Text Request