Neuroprotective Role of Transgenic PAF-Acetylhydrolase II in Mouse Models of Focal Cerebral Ischemia
Neuroprotective Role of Transgenic PAF-Acetylhydrolase II in Mouse Models of Focal Cerebral Ischemia
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DOI：
10.1161/01.str.0000257981.09329.d2
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发表时间：
2007-03
期刊：
影响因子：
8.3
通讯作者：
K. Umemura;I. Kato;Y. Hirashima;Y. Ishii;Takao Inoue;J. Aoki;N. Kono;T. Oya;N. Hayashi
中科院分区：
文献类型：
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作者：
K. Umemura;I. Kato;Y. Hirashima;Y. Ishii;Takao Inoue;J. Aoki;N. Kono;T. Oya;N. Hayashi
背景和目的：血小板活化因子（PAF）和氧化不饱和游离脂肪酸被认为加重了缺血后脑的神经元损伤。Ⅱ型PAF-乙酰水解酶（PAF-AH Ⅱ）不仅能通过其水解PAF的活性终止PAF的信号传导，而且还能保护细胞免受氧化应激。我们研究了PAF-AH II是否可以拯救脑神经元对抗缺血性损伤。方法-转基因小鼠过度表达人PAF-AH II的神经元和酶的表达进行了生化和组织化学检查。使小鼠经受短暂的大脑中动脉闭塞60分钟，随后再灌注24小时。TTC染色检测梗死灶，TUNEL荧光染色检测细胞凋亡。结果：Western blot和酶活性分析表明转基因小鼠脑中存在PAF-AH Ⅱ的过表达。在免疫组化中，在整个中枢神经系统中发现人PAF-AH II表达，特别是在新皮质、海马和基底神经节的神经元中。转基因小鼠的神经功能缺损评分、脑水肿指数和相对梗死体积（分别为1.30±0.72、1.12±0.04和14.0± 7.7%）均显著低于野生型小鼠（分别为2.56±0.93、1.23±0.12和31.9± 9.7%）（P<0.05）。转基因小鼠（皮质，5.2±3.3%;海马，3.4±7.0%）中凋亡细胞的数量也显著（P<0.001）低于野生型小鼠（皮质，41.1±16.9%;海马，58.9±15.3%）。结论：这些结果表明，PAF-AH II对缺血性损伤有很强的神经保护作用，并提示这种酶在脑缺血中的临床应用的可能性。
Background and Purpose— Platelet-activating factor (PAF) and oxidized unsaturated free fatty acids have been postulated to aggravate neuronal damage in the postischemic brain. Type II PAF-acetylhydrolase (PAF-AH II) not only terminates signals by PAF by its PAF-hydrolyzing activity but also protects cells against oxidative stress. We examined whether PAF-AH II can rescue cerebral neurons against ischemic insults. Methods— Transgenic mice overexpressing human PAF-AH II in neurons were generated and enzyme expressions were examined biochemically and histochemically. The mice were subjected to 60 minutes of transient middle cerebral artery occlusion followed by reperfusion for 24 hours. The infarction and apoptosis were estimated by TTC staining and fluorescence TUNEL staining, respectively. Results— Overexpression of PAF-AH II was found in brains of transgenic mice by Western blot and enzymatic activity analyses. In immunohistochemistry, human PAF-AH II expression was found throughout the central nervous system, especially in neurons of neocortex, hippocampus, and basal ganglia. The neurological deficit scores, cerebral edema index, and relative infarction volume were all significantly (P<0.05) lower in transgenic mice (1.30±0.72, 1.12±0.04, and 14.0±7.7%, respectively) than in wild-type mice (2.56±0.93, 1.23±0.12, and 31.9±9.7%, respectively). Percentages of apoptotic cells were also significantly (P<0.001) lower in transgenic mice (cortex, 5.2±3.3%; hippocampus, 3.4±7.0%) than in wild-type mice (cortex, 41.1±16.9%; hippocampus, 58.9±15.3%). Conclusions— These results indicate that PAF-AH II exerts strong neuroprotective effects against ischemic injury and suggest a possibility for clinical use of this enzyme in cerebral ischemia.