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目的探讨热习服对小鼠热射病脑损伤的保护作用。方法以C57小鼠分别建立热习服和热射病模型,实验分为对照组(CON组)、热习服组(HA组)、热射病组(HS组)、热习服后再接受热应激组(HA+HS组)。观察各组小鼠一般行为学表现、肛温变化、脑组织含水量及死亡率。HE染色观察病理改变,TUNEL染色观察神经元凋亡情况,透射电镜观察神经元形态改变。结果在43℃环境中暴露120min后,HS组肛温升高至(42.8±0.83)℃,死亡率为33%,脑组织含水量为(82.6±12.7)%;HA+HS组肛温升至(40.0±0.67)℃,未有动物死亡,脑组织含水量为(77.8±12.1)%,以上指标两组间差异具有统计学意义(P<0.01或P<0.05)。组织病理观察可见HS组脑组织细胞肿胀,胞质疏松,染色质边集,核明显固缩,内质网短小分散,排列紊乱,线粒体明显增大,线粒体DNA固缩,空泡化等,并有大量神经元凋亡,HA+HS组亦可见类似病理变化及神经元凋亡,但病变程度明显轻于HS组,而对照(CON)组及单纯热习服(HA)组以上指标均无明显变化。结论热射病可导致小鼠脑组织水肿,脑组织结构改变,神经元凋亡增加,对中枢神经系统功能损伤严重。热习服预处理可减轻脑损伤,具有明显的保护作用。
Objective To investigate the protective effect of heat acclimation on brain injury induced by heat stroke in mice. Methods C57 mice were randomly divided into control group (CON group), HA group (HA group), HS group (HS group) Heat stress group (HA + HS group). The mice in each group were observed in general behavior, rectal temperature changes, brain water content and mortality. Pathological changes were observed by HE staining. Neuronal apoptosis was observed by TUNEL staining. Morphological changes of neurons were observed by transmission electron microscopy. Results The rectal temperature increased to (42.8 ± 0.83) ℃ in HS group after 120min exposure at 43 ℃, the mortality rate was 33% and the water content in brain tissue was (82.6 ± 12.7)%. The rectal temperature increased in HA + HS group (40.0 ± 0.67) ℃. No animal died, and the water content of brain tissue was (77.8 ± 12.1)%. There was significant difference between the above two indexes (P <0.01 or P <0.05). Histopathological examination showed that the brain tissue of HS group was swollen, with loose cytoplasm, chromatin margination, obvious shrinkage of nucleus, short disintegration of endoplasmic reticulum, disordered arrangement of mitochondria, mitochondrial DNA shrinkage and vacuolization in HS group A large number of neurons apoptosis, HA + HS group also showed similar pathological changes and neuronal apoptosis, but the lesion was significantly lighter than the HS group, while the control group (CON) and hyperthermia (HA) group of the above indicators were not obvious change. Conclusion Heat-jet disease can cause edema in brain tissue, change of brain tissue structure, increase of neuron apoptosis and severe damage to the central nervous system. Heat preconditioning can reduce brain injury, with obvious protective effect.