摘要
目的 探讨脑创伤后bax和bcl xL 在mRNA和蛋白水平的变化规律及其与神经细胞凋亡发生、发展的关系。方法 在液压脑损伤模型中 ,应用逆转录聚合酶链反应、免疫组化分别检测大鼠脑创伤后不同时程bax和bcl xL 的表达 ;采用凋亡原位末端标记、电镜超微结构、DNA凝胶电泳观察脑创伤后细胞凋亡的形态和生化特征。结果 伤后 6h ,bcl xL mRNA下调 [伤侧半球为对侧的 (6 7.42± 7.5 4) % ],bcl xL 蛋白水平下降 [伤侧为对侧的 (85 .85± 5 .72 ) % ]。伤后 3d ,bcl xL mRNA和bcl xL 蛋白表达分别为对侧的 (39.97± 3.6 1) %和 (5 7.5 0± 6 .2 1) % ;baxmRNA和bax蛋白分别为对侧半球的 (2 0 3.95± 17.5 3) %和 (189.0 2± 7.2 3) %。伤后bax/bcl xL 比率升高比细胞凋亡提前出现 ,早期由于bcl xL 的表达下降 ,后期主要是由于bax的升高所致。结论 细胞凋亡及其调节基因的表达间具有一致性 ;脑创伤对bax和bcl xL 的调节发生在转录水平以前的某一环节。bax/bcl xL 平衡体系的维持或紊乱影响脑创伤后神经细胞生存或死亡。
Objective To investigate the alterations of bcl 2 gene family in rat brain and the molecular mechanism of neuronal apoptosis following traumatic brain injury. Methods Male Sprague Dawley rats were subjected to lateral fluid percussion brain injury (FPI) of moderate severity. bax and bcl x L mRNA and protein expression were detected by RT PCR and immunohistochemistry. In addition to morphological evidence of apoptosis, TUNEL histochemistry was used to identify DNA fragmentation in situ under both light and electron microscope, whereas characteristic internucleosomal DNA fragmentation of apoptosis was demonstrated by DNA gel electrophoresis.Results bcl x L mRNA and protein decreased in the ipsilateral hemisphere to the impact site as early as 6 h post injury (67.42±7.54% and 85.85±5.72% respectively). The decrease in bcl x L mRNA and protein preceded apoptosis which was observed at 12 h post injury. And this was the main cause of up regulation of the ratio of bax to bcl x L in the acute period(minutes to hours) follwoing lateral fluid percussion brain injury. bax mRNA and protein were observed to rise slowly, doubling at 3 d post injury, returned to sham level slowly. The delayed cell death (days～weeks) may be associated with the up regulation of pro apoptotic gene bax.Conclusion The expression of bcl x L and bax coincides with apoptosis following TBI. The regulation of bax and bcl x L by TBI occurs at a point before transduction. The balance of bax/bcl x L ratio determines assuine or death of neurocytes following FPI.
出处
《上海医学》
CAS
CSCD
北大核心
2001年第7期403-406,共4页
Shanghai Medical Journal
基金
军队九五指令性课题 :颅脑战创伤脑保护的基础与应用研究 ( 96L0 3 6)
