泛素羧基末端水解酶-1在重症中暑小鼠脑损伤组织中的表达

Expression of ubiquitin C-terminal hydrolase-L1 and heatstroke-induced brain injury in mice

目的泛素羧基末端水解酶-1(ubiquitin C-terminal hydrolase-L1,UCH-L1)表达异常对脑损伤的诊断及预后有一定价值。文中通过制备热打击中暑动物模型,探讨重症中暑脑组织和血清中UCH-L1水平的变化及意义。方法 BALB/c小鼠按随机数字法分为对照组和热打击组,对照组始终置于常温(25.0±0.5)℃,相对湿度(35±5)%环境下,热打击组置于仿真高温气候舱内,舱内温度(35.5±0.5)℃,相对湿度(60±5)%,记录小鼠直肠温度(Tc),当热打击小鼠Tc达42℃移置(25.0±0.5)℃、(35±5)%相对湿度环境下,复温分为0、6、12、24 h 4个时间点;分离中暑动物脑组织行HE染色,显微镜下观察并行脑组织神经元神经病理损伤评分;ELISA法检测中暑动物血清及脑组织中UCH-L1表达水平;Western blot和免疫组化法检测中暑动物脑组织中UCH-L1表达水平。结果小鼠经热打击后,随着复温时间延长(6、12、24 h),神经元肿胀、排列紊乱,细胞皱缩,核固缩深染细胞数不断增多,神经病理损伤评分明显增高,分别为(2.78±0.71)、(3.21±0.56)和(3.36±0.63)分,与对照组的(0.43±0.10)分比较的差异有统计学意义(P均<0.01);ELISA检测血清和脑组织中UCH-L1水平,发现随着复温时间延长其表达增高,与对照组相比差异有统计学意义(P<0.05);Western blot检测结果表明热打击后脑组织中UCH-L1表达逐渐增多,与对照组相比差异有统计学意义(P<0.01);免疫组化法检测发现,热打击组脑组织中UCH-L1表达逐渐增多,表现为神经元细胞质中淡棕色染色逐渐增强。结论重症中暑导致的脑损伤呈时间依赖性加重,血清及脑组织中UCH-L1表达异常增高可作为重症中暑脑损伤程度标志物。

Objective The abnormal expression of ubiquitin C-terminal hydrolase-L1（ UCH-L1） has an important role in the diagnosis and prognosis of brain damage. This study was to investigate the changes of UCH-L1 in the serum and brain tissue in the mouse model of heat stress. Methods Twelve BALB/c mice were randomly divided into a control and a heat stress group of equal number,the former placed at a temperature of（ 25. 0 ± 0. 5） ℃ and a relative humidity of（ 35 ± 5） % and the latter in a simulated incubator at（ 35. 5 ± 0. 5） ℃ and a relative humidity of（ 60 ± 5） %. When the rectal temperature reached 42 ℃,the animals were removed from the incubator and cooled at an ambient temperature of（ 25. 0 ± 0. 5） ℃ and a humidity of（ 35 ± 5） % for 0,6,12,and 24 h. Then the brain tissues of all the animals were harvested for HE staining,evaluation of neuronal injury under the light microscope,measurement of the UCH-L1 levels in the serum and brain tissue by ELISA,Western blot,and immunohistochemistry,respectively.Results With the prolonged exposure to heat,the mice exhibited swollen and disorderly arranged neurons, shrunken cells, and contracted and deeply stained nuclei,with significantly higher scores on nerve pathological injury evaluation at 6,12,and 24 h（ 2. 78 ±0. 71,3. 21 ± 0. 56,and 3. 36 ± 0. 63） than the control mice（ 0. 43± 0. 10）（ P〈0. 05）. ELISA showed remarkably elevated levels of UCH-L1 in the serum（ F = 147. 7,P = 0. 05） and brain tissue（ F =145. 7,P = 0. 05） in the heat stress group as compared with the control,and Western blot also revealed a markedly higher expression of UCH-L1 in the brain tissue in the former group than in the latter（ F = 261. 2,P = 0. 01）. Immunohistochemistry manifested that,with the prolonged exposure to heat,the UCH-L1 expression in the brain tissue was characterized by gradually increased light brown of the neurons at staining. Conclusion Severe heatstroke causes brain injury in a time-dependent manner,and the abnormally elevated levels of UCH-L1 in the serum and brain tissue can be a marker of heatstroke-induced brain injury.