癫痫大鼠海马出芽苔藓纤维突触的超微结构特征

目的:探讨匹罗卡品颞叶癫痫大鼠海马出芽苔藓纤维突触的超微结构特征及其在颞叶癫痫发病机制中的作用。方法:采用Timm组化染色标记出芽苔藓纤维突触末端,在电镜下观察新生突触的类型、比例、定位、以及突触后靶成分。结果:颞叶癫痫大鼠齿状回内分子层可见到银标记的突触末端,出芽苔藓纤维突触主要是轴棘型非对称性突触,其次是轴树型非对称性突触,偶可看到出芽轴突和颗粒细胞体形成突触联系。结论:轴棘型非对称性突触是颞叶癫痫大鼠海马出芽苔藓纤维突触的主要类型,出芽苔藓纤维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,而且形成的新的兴奋性环路可能在颞叶癫痫的发生与发展中起重要作用。

Ultrastmctural features of sprouted mossy fiber synapses in hippocampus of chronic temporal lobe epilepsy rats induced by pilocarpine

Objective: To characterize the ultrastructural features of sprouted mossy fiber synapses in hippocampus of pilocarpine-treated rats and its effects in the mechanism of chronic temporal lobe epilepsy. Methods: The sprouted mossy fiber synaptic terminals were labeled by Timm histochemistry and the types,number, location,postsynaptic target of new synapses were observed by electron microscopy. Results: The Timm method revealed dark silver granules in the inner molecular layer of chronic temporal lobe epilepsy rats induced by pilocarpine. The sprouted mossy fiber synapses in epileptic rats most commonly form asymmetric synapses with dendritic spines,less frequently with dendritic shafts ,and occasionally with granule cell somata. Conclusion: Axospinous asymmetric synapses are the most common type of synapse formed by sprouted mossy fiber terminals in temporal lobe epilepsy rats. The ultrastructural features of sprouted mossy fiber synapses support the viewpoint that the reorganization of synapses prominently involves formation of recurrent excitatory circuits, which probably play a important role in the mechanism of chronic temporal lobe epilepsy.