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目的探讨颞叶癫痫(TLE)海马出芽苔藓纤维(MF)突触的超微结构特征在其发病机制中的作用以及神经轴突诱向因子 netrin-1表达与 MF 突触重建的关系。方法锂-匹罗卡品诱导大鼠 TLE,Timm 组化染色标记出芽 MF 突触末端,在电镜下观察新生突触的超微结构特征。用原位杂交方法检测 netrin-1在大鼠海马的表达。结果出芽 MF 突触主要是轴棘型非对称性突触,偶可看到出芽轴突和兴奋性颗粒细胞体形成突触联系。癫痫状态(SE)后7d,在海马齿状回颗粒细胞层可见netrin-1 mRNA 表达上调,并持续至 SE 后28d。其表达的时空顺序和海马 MF 出芽以及突触重组相一致。结论出芽 MF 突触的超微结构特性支持重组突触形成重复的兴奋性环路;神经轴突诱向因子 netrin-1在出芽 MF 的靶向性生长和突触重组过程中可能起重要作用。
Objective To investigate the ultrastructural features of mtDNA synapses in the temporal lobe epilepsy (TLE) hippocampus and its relationship with the pathogenesis of MF and the relationship between netrin-1 and MF synaptic remodeling. Methods The L-pilocarpine-induced TLE and Timm staining marked the synaptic terminals of MF, and the ultrastructural features of the synapses were observed under electron microscope. In situ hybridization was used to detect the expression of netrin-1 in rat hippocampus. Results Sprouting MF synapses are mainly axial spines asymmetric synapses, even see budding axons and excitatory granulosa cell synaptic connections. Seven days after epilepticus (SE), netrin-1 mRNA was up-regulated in the granular layer of dentate gyrus in the hippocampus and continued until 28 days after SE. The spatiotemporal order of expression is consistent with MF sprouting in hippocampus and synaptic reorganization. Conclusions The ultrastructure of sprouting MF synapse supports the formation of repetitive excitatory loops by recombinant synapses. Netrin-1, a neurotrophic factor, may play an important role in the targeted growth and synaptic reorganization of sprouting MF.