Department of Neurology, The Affiliated Jiangyin Hospital, Medical College of Southeast University, 163 Shoushan Road, Jiangyin 214400, Jiangsu Province, China.
Neurochem Int. 2011 Feb;58(2):224-33. doi: 10.1016/j.neuint.2010.12.008. Epub 2010 Dec 15.
Cerebral ischemia is a major cause of adult disability and death worldwide. Evidence suggests that Bax-dependent initiation and activation of intrinsic apoptotic pathways contribute to ischemic brain injury. We investigated the Bax-inhibiting peptide VPALR, designed from the rat Ku70-Bax inhibiting domain, on the apoptotic neuronal cell death and behavioral deficits following global cerebral ischemia. The pentapeptide was infused into the left lateral ventricle of the rat brain by intracerebroventricular (i.c.v.) injection 1 h after cerebral ischemia, and results showed that it highly permeated hippocampal neurons and bound to Bax protein in vivo. Post-treatment with VPALR reduced the delayed neuronal damage by approximately 78% compared to the non-treated ischemic control and scrambled peptide-treated rats. TUNEL analysis revealed that VPALR markedly reduced the ischemia-induced increase in apoptotic neuronal death in rat hippocampal CA1 region. VPALR post-treatment also significantly attenuated Bax activation and its mitochondrial translocation as compared with scrambled peptide-treated animals. Concomitantly, Bax-inhibiting peptide-treated rats showed reduced cytochrome c release from mitochondria to cytosol and reduced caspase-3 activation in response to cerebral ischemia, indicating that activation of the intrinsic apoptotic pathway was reduced. Furthermore, Bax-inhibiting peptide improved spatial learning and memory performance in the Morris water maze, which was seriously affected by global cerebral ischemia. In conclusion, Bax inhibition by cell-permeable pentapeptides reduced apoptotic neuronal injury in the hippocampal CA1 region and behavioral deficits following global ischemia. These results suggest that Bax is a potential target for pharmacological neuroprotection and that Bax-inhibiting peptide may be a promising neuroprotective strategy for cerebral ischemia.
脑缺血是全世界导致成人残疾和死亡的主要原因。有证据表明，Bax 依赖性起始和激活内在凋亡途径有助于缺血性脑损伤。我们研究了 Bax 抑制肽 VPALR，它是从大鼠 Ku70-Bax 抑制结构域设计而来的，用于研究全脑缺血后凋亡性神经元细胞死亡和行为缺陷。该五肽通过立体定向侧脑室注射（i.c.v.）在脑缺血后 1 小时注入大鼠脑内，结果表明它高度渗透到海马神经元中，并在体内与 Bax 蛋白结合。与未治疗的缺血对照和乱序肽治疗的大鼠相比，VPALR 后处理使迟发性神经元损伤减少了约 78%。TUNEL 分析显示，VPALR 显著减少了缺血诱导的大鼠海马 CA1 区凋亡性神经元死亡的增加。与乱序肽处理的动物相比，VPALR 后处理还显著减弱了 Bax 的激活及其向线粒体的易位。同时，Bax 抑制肽处理的大鼠在脑缺血后显示出从线粒体到细胞质的细胞色素 c 释放减少和 caspase-3 激活减少，表明内在凋亡途径的激活减少。此外，Bax 抑制肽改善了在 Morris 水迷宫中的空间学习和记忆表现，这受到全脑缺血的严重影响。总之，细胞通透性五肽通过抑制 Bax 减少了海马 CA1 区的凋亡性神经元损伤和全脑缺血后的行为缺陷。这些结果表明 Bax 是药理学神经保护的潜在靶点，Bax 抑制肽可能是脑缺血的一种有前途的神经保护策略。
