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目的观察大鼠海马脑区缺血/再灌注后ephrinA3激活EphA4受体对海马CA1区神经元凋亡的影响。方法采用经典的四血管夹闭大脑缺血/再灌注模型,分别脑室内给予EphA4受体激动剂ephrinA3-Fc以及EphA4受体阻断剂EphA4-Fc,通过TUNEL染色观察在缺血/再灌注后6、24、48h各组海马神经元凋亡情况,同时检测Caspase 3的活性,以观察EphA4/ephrinA3系统活化与CA1区神经元凋亡的关系。结果侧脑室内给予激动剂ephrinA3-Fc后,Caspase 3的活性较单纯缺血/再灌注组有明显升高(2.76±0.15 vs 2.28±0.28,P<0.05;24h:2.24±0.24 vs 2.20±0.19,P<0.05;48h:2.04±0.44 vs 1.90±0.29,P<0.05),同时神经元的凋亡亦有增加(31.8±4.40%vs 26.33±5.32%,P<0.05;24h:25.50±4.03%vs 23.8±5.56%,P<0.05;48h:22.17±4.52%vs 19.0±4.34%,P<0.05)。侧脑室给予阻断剂EphA4-Fc后,Caspase 3的活性较单纯再灌注组降低(6h:1.73±0.30 vs 2.28±0.28,P<0.05;24h:1.52±0.26 vs 2.20±0.19,P<0.05;48h:1.43±0.23 vs 1.90±0.29,P<0.05),而神经元的凋亡亦明显减少(6h:17.5±4.97%vs 26.33±5.32%,P<0.05;24h:15.0±4.47%vs 23.8±5.56%,P<0.05;48h:12.0±3.46%vs 19.0±4.34%,P<0.05),提示ephrinA3-EphA4系统的活化可能参与了再灌注后神经元凋亡的发生。结论 EphA4的活化可能通过激活Caspase 3通路促进了缺血/再灌注后海马脑区神经元的凋亡,阻断EphA4的活化可以抑制Caspase 3的激活,减少海马脑区神经元的凋亡,从而发挥神经保护作用。
Objective To observe the effect of ephrinA3-activated EphA4 receptor on neuronal apoptosis in the hippocampal CA1 area after cerebral ischemia / reperfusion in the hippocampus. Methods The model of cerebral ischemia / reperfusion was established by a classic four-vessel occlusion model. EphA4 receptor agonist ephrinA3-Fc and EphA4 receptor antagonist EphA4-Fc were intraventricularly administered. The apoptosis of hippocampal neurons was detected at 6, 24 and 48 hours, and the activity of Caspase 3 was detected at the same time to observe the relationship between EphA4 / ephrinA3 activation and neuronal apoptosis in CA1 area. Results After intracerebroventricular injection of ephrinA3-Fc, the activity of Caspase 3 was significantly higher than that of ischemia / reperfusion group (2.76 ± 0.15 vs 2.28 ± 0.28, P <0.05; 24h: 2.24 ± 0.24 vs 2.20 ± 0.19 , P <0.05; 48h: 2.04 ± 0.44 vs 1.90 ± 0.29, P <0.05), meanwhile the apoptosis of neurons also increased (31.8 ± 4.40% vs 26.33 ± 5.32%, P <0.05; 24h: 25.50 ± 4.03% vs 23.8 ± 5.56%, P <0.05; 48h: 22.17 ± 4.52% vs 19.0 ± 4.34%, P <0.05). After intracerebroventricular administration of EphA4-Fc, the activity of Caspase 3 decreased compared with that of the reperfusion group (6h: 1.73 ± 0.30 vs 2.28 ± 0.28, P <0.05; 24h: 1.52 ± 0.26 vs 2.20 ± 0.19, P < 48h: 1.43 ± 0.23 vs 1.90 ± 0.29, P <0.05), while the apoptosis of neurons was also significantly reduced (6h: 17.5 ± 4.97% vs 26.33 ± 5.32%, P <0.05; 24h: 15.0 ± 4.47% vs 23.8 ± 5.56%, P <0.05; 48h: 12.0 ± 3.46% vs 19.0 ± 4.34%, P <0.05), suggesting that the activation of ephrinA3-EphA4 system may be involved in the neuronal apoptosis after reperfusion. Conclusion Activation of EphA4 may promote the apoptosis of neurons in the hippocampus after ischemia / reperfusion injury by activating the Caspase 3 pathway. Blocking the activation of EphA4 may inhibit the activation of Caspase 3 and decrease the apoptosis of neurons in the hippocampus. Play a neuroprotective effect.