中文摘要：

目的探讨不同时间窗的延迟亚低温（MHT）治疗对颅脑创伤（TBI）大鼠脑组织Bcl-2、Bax和Caspase-3蛋白表达的影响。方法36只清洁级成年雄性SD大鼠随机均分为常温治疗（NT）组、MHT15min组、MHT2h组及MHT4h组。采用电子可控性皮质损伤装置制备大鼠TBI模型，造模完成后NT组给予常温（37℃）维持6h，3个亚低温组分别于TBI后15min、2h、4h给予低温（33.0±1.0）℃维持6h。3d后对各组大鼠进行改良神经功能缺损评分（mNSS），HE染色观察海马CA1区组织病理学变化，免疫组化染色和Westernblot检测Bcl-2、Bax和Caspase-3蛋白表达情况。结果各组大鼠表现为不同程度的神经行为缺陷，与NT组相比，3个亚低温组mNSS评分均降低（P<0.01）。HE染色结果显示3个亚低温组神经细胞结构较规则、排列相对整齐，神经元坏死数量减少，核碎裂、溶解现象减轻。与NT组相比，3个亚低温组均能上调Bcl-2表达，下调Bax和Caspase-3表达（P<0.05）。以上实验结果均显示MHT15min组疗效优于MHT2h组，而MHT2h组和MHT4h组疗效相当。结论恰当地延迟亚低温治疗在一定程度上能够抑制神经细胞凋亡，缓解脑损伤进展。

英文摘要：

Objective To explore the effects of delayed mild hypothermia(MHT)in different time windows on the expressions of Bcl-2,Bax and Caspase-3in brain tissue of model rats with traumatic brain injury(TBI).Methods Thirtysix clean adult male SD rats were randomly divided into NT group(normal temperature),MHT15min group,MHT2h group and MHT4h group.TBI rat model was established by electronical controlled cortical injury device.The rats in the NT groupwere treated with normothermia(37℃)and the rats in the three hypothermia groups were implemented with low temperature(33.0±1.0)℃at15min,2h and4h for6h respectively after establishment of TBI model.The modified neurological senerity scores(mNSS),morphological changes in hippocampal CA1areas,immunohistochemical staining and Western blot assay forBcl-2,Bax and Caspase-3were compared3days after TBI between the four groups.Results The neurological behavioral deficits were found in each group.Compared with the NT group,the mNSS were decreased in the three hypothermia groups(P<0.01).The results of HE staining showed that the structure of neurons was regular and arranged neatly,and the numberof neurons decreased with alleviated nuclear fragmentation and dissolution in hypothermia groups.Compared with the NTgroup,the expression of Bcl-2was upregulated,and the expressions of Bax and Caspase-3were downregulated in three hypothermia groups(P<0.05).The above experimental results were superior in MHT15min group to MHT2h group,andthe therapeutic effect in MHT2h group was similar to MHT4h group.Conclusion The proper delayed mild hypothermia SDStreatmentcould inhibit neuronal apoptosis and alleviate brain damage.