Krajewski S, Mai J K, Krajewska M, Sikorska M, Mossakowski M J, Reed J C
La Jolla Cancer Research Foundation, Oncogene and Tumor Suppressor Gene Program, California 92037, USA.
J Neurosci. 1995 Oct;15(10):6364-76. doi: 10.1523/JNEUROSCI.15-10-06364.1995.
The patterns of expression of the bcl-2, bax, and bci-X genes were examined immunohistochemically in neurons of the adult rat brain before and after 10 min of global ischemia induced by transient cardiac arrest. High levels of the cell death promoting protein Bax and concomitant low levels of the apoptosis-blocking protein Bcl-2 were found in some populations of neurons that are particularly sensitive to cell death induced by transient global ischemia, such as the CA1 sector of the hippocampus and the Purkinje cells of the cerebellum. Moreover, within 0.5 to 3 hr after an ischemic episode, immunostaining for Bax was markedly increased within neurons with morphological features of degeneration in many regions of the brain. Use of a two-color staining method for simultaneous analysis of Bax protein and in situ detection of DNA-strand breaks revealed high levels of Bax immunoreactivity in many neurons undergoing apoptosis. Postischemic elevations in Bax protein levels in the hippocampus, cortex, and cerebellum were also demonstrated by immunoblotting. At early times after transient ischemia, regulation of Bcl-2 and Bcl-x protein levels varied among neuronal subpopulations, but from 3 hr on, those neurons with morphological evidence of degeneration uniformly contained reduced levels of Bci-2 and particularly Bci-X immunoreactivity. The findings suggest that differential expression of some members of the bcl-2 gene family may play an important role in determining the relative sensitivity of neuronal subpopulations to ischemia and that postischemic alterations in the expression of bax, bcl-2, and bcl-x may contribute to the delayed neuronal cell death that occurs during the repurfusion phase after a transient ischemic episode.
采用免疫组织化学方法，检测了成年大鼠全脑缺血10分钟（由短暂性心脏停搏引起）前后bcl-2、bax和bcl-X基因的表达模式。在一些对短暂性全脑缺血诱导的细胞死亡特别敏感的神经元群体中，发现促细胞死亡蛋白Bax水平较高，而凋亡抑制蛋白Bcl-2水平较低，如海马体的CA1区和小脑的浦肯野细胞。此外，在缺血发作后0.5至3小时内，大脑许多区域具有变性形态特征的神经元内，Bax免疫染色明显增加。采用双色染色法同时分析Bax蛋白和原位检测DNA链断裂，发现在许多正在发生凋亡的神经元中Bax免疫反应性较高。免疫印迹法也证实了海马体、皮质和小脑中缺血后Bax蛋白水平升高。短暂性缺血后的早期，Bcl-2和Bcl-x蛋白水平在神经元亚群中的调节有所不同，但从3小时起，那些具有变性形态学证据的神经元中，Bcl-2水平普遍降低，尤其是Bcl-X免疫反应性降低。这些发现表明，bcl-2基因家族某些成员的差异表达可能在决定神经元亚群对缺血的相对敏感性方面起重要作用，并且缺血后bax、bcl-2和bcl-x表达的改变可能导致短暂性缺血发作后再灌注期发生的延迟性神经元细胞死亡。
