The Effect And Preliminary Mechanism Of Heat Acclimatization On Radiation Damage Combined With Heat And Humid Environment

Object To investigate the effect of heat acdimatization(HA) on y radiation irradiated mice combined heat and humid environment(HHE), and probe into the methods and preliminary mechanism to alleviate radiation damage on HHE. Methods 1. Ninety male mice were randomly divided into 3 groups, room temperature(RT) group, HHE group and heat acclimatization(HA) group. The HA group mice were exposed to repeated bouts of HHE (2h at 36C) every day for 2 weeks, and then after all being irradiated by y radiation at the dosage of 6.5 Gy, the RT mice put into RT environment immediately, the HHE and HA mice were treated with HHE after 2h along with the RT mice. The survival index was then obtained by calculating the death rate within 30 days. 2After being irradiated by Co-60r radiation at the dosage of median lethal dose in 30 days(LD50/30,6.5 Gy), the blood , spleen and thymus of all RT, HHE and HA groups were examiner at the day post-irradiation 8h,l,3,7 and 16 days respectively. The HSP70 in blood , spleen vs body weight ratio(SVBWR), thymus vs body weight ratio(TVBWR) were analyzed in order to find out the mechanism of changes in HHE. Result 1 compared to the mice treated with RT, there is a distinguish difference between the death rate, average survival time and the met-survival time when the mice were treated with HHE 2h after being irradiated by y radiation(P<0.05), but the survival index of HA mice enhanced, compared with RT and HHE mice. 2 The atrophy of spleen and thymus was more serious in the mice treated with RT than HHE, but not HA, and then SVBWR, TVBWR have approximate sequel; 3 The content of HSP70 from the blood in the different groups increased at different time period after radiation, which was compared with normal control group. At day 1 after radiation, the increasing ratio of the heat group and HHE groupwas most in all of the groups. At day 3 and 7, the content of HSP70 in the groups of HA, HHE and RT significantly increased, and reached the highest level at day 7. The content of HSP70 of the heat group decreased, but was still higher than normal level. Though the expression of HSP70 in all groups was dropped at day 16, it was higher than normal level. Conclusions HHE aggravated the radiation damage and increase the death rate, but HA could alleviate the radiation injury aggravated by HHE. One of the mechanisms may be the enhancement of HSP70 in body before mice being irradiated by r radiation.