热习服对热射病小鼠中枢神经细胞自噬及凋亡的影响

Heat acclimation attenuates neuronal autophagy and apoptosis in heat stroke mice

目的探讨热习服对热射病小鼠中枢神经细胞自噬及凋亡的影响。方法 48只C57雄性小鼠分为正常对照(CON)组、热习服(HA)组、热射病(HS)组、热习服+热射病(HA+HS)组,分别建立热习服和热射病模型。观察比较各组动物脑组织含水量,脑切片HE染色观察病理学改变,FJB染色观察神经细胞变性情况,TUNEL染色标记凋亡神经细胞,免疫荧光标记自噬神经细胞,Western blot检测Caspase 3及LC3蛋白表达。结果在43℃环境中暴露120 min后,HA+HS组脑组织含水量为(78.54±0.25)%,显著低于HS组的(79.64±0.21)%,差异有统计学意义(P<0.05);脑组织病理学显示HS组细胞肿胀,胞质疏松,染色质边集,核明显固缩、破裂、溶解,细胞空泡化明显,神经元变性和凋亡加剧,HA+HS组细胞损伤程度明显减轻,神经元变性和凋亡减轻,Caspase-3蛋白表达明显下降(P<0.05);HA、HA+HS和HS组神经细胞自噬均明显增强,但与HS组相比,HA+HS组自噬程度下降,且LC3蛋白表达明显降低(P<0.05)。结论热习服对热射病小鼠脑损伤具有保护作用,并可减轻热射病导致的中枢神经细胞自噬及凋亡。

Objective To determine the effect of heat acclimation （HA） on the autophagy and apoptosis of cerebral neurons in mice after heat stroke （HS）. Methods A total of 48 C57 male mice were randomly divided into control （CON） group, HA group, HS group and HA ＋ HS group. After the establishment of HA and HS models, the brain water content was measured, pathological changes of the brain were observed by HE staining, neuronal degeneration was tested by Fluoro-Jade B （FJB） staining, neuronal apoptosis was detected by TUNEL staining and Western blotting, and the expression of Caspase 3 and LC3 was measured by immunofluoreseence assay and Western blotting. The results were compared among the groups. Results After exposure to 43 ℃ for 120 min, the brain water content was significantly lower in HA ＋ HS group than HS group [ （78.54 ± 0.25 ） % vs （ 79.64 ±0. 21 ） %, P 〈 0.05 ]. Pathological observation displayed swollen cells, rarefied cytoplasm, chromatin concentration and edge accumulation, nuclear pyknosis, rupture and dissolution, obviously cell vacuolation, and exacerbated neuronal degeneration and apoptosis in HS mice, but the damage degrees were milder in the HA ＋ HS mice with remarkably attenuated neuronal degeneration and apoptosis and decreased expression of Caspase 3 （P 〈 0.05 ）. Heat exposure elevated the autophagy in the HA, HA ＋ HS and HS groups, but the autophagy and LC3 expression were attenuated after HA preconditioning when compared with HS mice. Conclusion HA plays protective role in brain injury in HS-induced mice, and down-regulates the neuronal autophagy and apoptosis.