银杏叶提取物上调海马脑源性营养因子和神经肽2受体表达、增强突触重建而改善发育期癫痫大鼠认知功能的研究

目的 观察银杏叶提取物(EGb)对发育期点燃癫痫大鼠治疗前后学习记忆及脑组织海马中脑源性营养因子(BDNF)、神经肽2受体(NPY2R)、突触素P38、突触后致密蛋白95(PSD95)表达及突触超微结构的影响,探讨EGb改善认知功能的可能作用机制.方法 戊四氮(PTZ)诱导大鼠慢性点燃模型,Morris水迷宫观察干预治疗前后大鼠学习记忆变化,Western blot和免疫组化分别检测海马中BDNF、NPY2R、P38、PSD95蛋白的含量分布情况,电镜观察突触超微结构.结果 (1)Morris水迷宫测试结果显示PTZ点燃大鼠的潜伏期长于NS组(P<0.05),经EGb治疗后的大鼠潜伏期较点燃组明显下降(P<0.05).相应地点燃大鼠的跨越平台次数明显少于NS组(P<0.05),经EGb治疗后大鼠的跨越平台次数则多于相应的未治疗组(P<0.05).(2)点燃大鼠海马中BDNF蛋白含量明显高于NS组(P<0.05),EGb的治疗进一步提高了大鼠BDNF蛋白含量(P<0.05),BDNF免疫阳性细胞分布以皮质区最高,其次分别为海马CA3区、CA2区和DG.相应地点燃大鼠海马内NPY2R蛋白含量也显著高于NS组(P<0.05),但是,EGb的治疗可以降低大鼠的NPY2R蛋白含量(P<0.05),NPY2R免疫阳性细胞主要分布于海马DG区,皮质区次之.(3)点燃大鼠脑内P38和PSD95蛋白含量均低于NS组(P<0.05),EGb的治疗使得P38和PSD95表达量明显高于点燃组、甚至超过NS组(P<0.05).(4)在透射电镜下点燃大鼠海马神经元胞体固缩浓染,细胞水肿,突起膜发生断裂,突触前后膜结构模糊,突触小泡减少,突触后致密物变薄,而EGb的治疗可以减轻细胞水肿、致密物稍增厚.结论 EGb治疗后发育期癫痫大鼠海马BDNF、NPY2R、P38和PSD95表达增强,受损的突触结构得到改善,可能参与了EGb改善点燃大鼠的学习记忆过程.

Effects of extract of Ginkgo Bilob on cognitive function and expression of BDNF,NPY2R and synaptic reconstruction in juvenile rats with kindled seizure by pentylenetetrazol

Objective To observe effects of extract of Ginkgo Bilob(EGb)on cognitive function and expression of BDNF,NPY2R and synaptic reconstruction in juvenile rats with kindled seizure by pentylenetetrazol.Methods SD rats with postnatal 21 d were induced chronic kindling seizure by pentylenetetrazol(PTZ),then was given EGb 300 mg·kg-1·d-1 or placebo.Morris water maze was used to study the learning and memory in rats.BDNF,NPY2R,P38,PSD95 protein in hippocampus were detected by Western blot and immunohistochemical staining.Synaptic ultrastructure in hippocampus was surveyed by transmission electron microscopy(TEM).Results(1)Under Morris water maze the escape latency of rats with kindled seizure was longer than that in NS group(P<0.05),but decreased more shorter than kindled rats after EGb.The cross-platform times of kindled rats in maze were less than that of NS rats,and were improved after EGb.(2)The content of BDNF protein in hippocampus in kindled rats were higher than that in NS rats(P<0.05),but lower than that in rats with EGb treatment(P<0.05).BDNF immunoreactive cells were mainly distributed in the cortex followed by the hippocampal CA3,CA2 and DG areas.Proportionately,the hippocampal NPY2R protein in kindled rats were higher than that in NS,and increased significantly by EGb.NPY2R immunoreactive cells were mainly distributed in the hippocampal DG area,cortex.(3)P38 and PSD95 protein in kindled rats were lower than that in normal rats(P<0.05),but significantly raised after EGb treatment.(4)Under TEM,the hippocampal neurons of rats in P-A7 were seen cell body condensation,cell swelling,synaptic membrane rupture,blur of presynaptic and postsynaptic membrane,reduced synaptic vesicles,thinned postsynaptic density.But they were appreciably improved after EGb treatment.Conclusions Expression of BDNF,NPY2R,P38,and PSD95 in hippocampus of juvenile rat with chronic kindled seizure after EGb treatment had significantly changed.Impaired synaptic structure had been improved.The expression of BDNF,NPY2R and synaptic reconstruction may be involved in mechanism of EGb improving learning-memory in kindled juvenile rats.