Apoptosis-Suppressor Gene bcl-2 Expression after Traumatic Brain Injury in Rats
Apoptosis-Suppressor Gene bcl-2 Expression after Traumatic Brain Injury in Rats
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DOI：
10.1523/jneurosci.17-23-09172.1997
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发表时间：
1997-12
期刊：
影响因子：
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通讯作者：
R. Clark;J. Chen;Simon C Watkins;P. Kochanek;M. Chen;R. A. Stetler;J. E. Loeffert;S. H. Graham
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文献类型：
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作者：
R. Clark;J. Chen;Simon C Watkins;P. Kochanek;M. Chen;R. A. Stetler;J. E. Loeffert;S. H. Graham
实验性创伤性脑损伤（TBI）后神经元死亡具有凋亡和坏死双重特征。创伤周围皮层、海马和齿状回的神经元尤其脆弱。凋亡抑制基因bcl-2在缺血和癫痫诱导的损伤后的脑中被诱导，并且可能用于调节神经元死亡。本实验观察了大鼠脑外伤后bcl-2 mRNA和蛋白的表达。为了确定在具有凋亡证据的细胞中是否发生bcl-2蛋白表达，使用（1）抗bcl-2的抗体，（2）双苯甲酰亚胺染料进行三重标记研究以检查大体核形态，和（3）末端脱氧核苷酸转移酶介导的生物素-dUTP缺口末端标记（TUNEL）以评估DNA片段化。在6和24小时，bcl-2 mRNA在同侧创伤周围皮质、海马和齿状回中被诱导。到72小时，bcl-2 mRNA仅在皮质中检测到增加。在8、24、72和168小时，在同侧皮质和海马中诱导bcl-2蛋白。表达bcl-2蛋白的细胞包括创伤周围皮质、海马、门和齿状回的神经元。表达bcl-2的神经元大体核形态正常。此外，在表达bcl-2蛋白的神经元中很少看到DNA断裂的生化证据，其模式特征为凋亡或坏死（在观察到的TUNEL阳性细胞中，bcl-2与TUNEL共定位于0-2%）。这些数据表明，bcl-2可能在TBI后神经元死亡的调节中发挥重要作用，并且它们支持bcl-2作为诱导型神经保护基因的作用。
Neuronal death after experimental traumatic brain injury (TBI) has features of both apoptosis and necrosis. Neurons in the peritrauma cortex, hippocampus, and dentate gyrus are particularly vulnerable. The apoptosis-suppressor gene bcl-2 is induced in brain after ischemia and epilepsy-induced injury and may serve to regulate neuronal death. We studied expression of bcl-2 mRNA and protein after experimental TBI in rats. To determine whether bcl-2 protein expression occurred in cells with evidence of apoptosis, triple-labeling studies were performed using (1) antibody against bcl-2, (2) bis-benzimide dye to examine gross nuclear morphology, and (3) terminal deoxynucleotidyl transferase-mediated biotin-dUTP nick-end labeling (TUNEL) to assess for DNA fragmentation. At 6 and 24 hr,bcl-2 mRNA was induced in ipsilateral peritrauma cortex, hippocampus, and dentate gyrus. By 72 hr the increase inbcl-2 mRNA was detected only in cortex. bcl-2 protein was induced at 8, 24, 72, and 168 hr in ipsilateral cortex and hippocampus. Cells expressing bcl-2 protein included neurons in the peritrauma cortex, hippocampus, hilus, and dentate gyrus. The gross nuclear morphology of neurons expressing bcl-2 appeared normal. Furthermore, biochemical evidence of DNA fragmentation, in a pattern characteristic of either apoptosis or necrosis, was seldom seen in neurons expressing bcl-2 protein (bcl-2 colocalized with TUNEL in 0–2% of TUNEL-positive cells observed). These data suggest that bcl-2 may play an important role in the regulation of neuronal death after TBI, and they support a role for bcl-2 as an inducible neuroprotective gene.