皮质发育障碍大鼠小脑回形态学和海马苔藓纤维发芽的研究

目的 探讨液氮损伤诱导局灶性皮质发育障碍大鼠海马形态学及苔藓纤维发芽的情况。方法 实验随机分为正常对照组、假手术组和液氮损伤组，建立局灶性皮质发育障碍动物模型，察看其行为改变；采用常规HE染色、Nissl染色和Timm’s硫化银组织化学方法染色，肉眼和光镜下观察大鼠脑皮质形态变化，光镜下评估海马苔藓纤维发芽情况，各组数据取苔藓纤维发芽评分，采用非参数秩和Kruskal—Wallis H检验，组间两两比较用Nemenyi法。结果 液氮损伤组大鼠行为轻微改变，鼠脑嘴尾方向形成了一小的脑回，同侧海马CA3区有苔藓纤维发芽．而正常对照组和假手术组却没有。结论 幼鼠早期液氮损伤可导致小脑回形成及海马CA3区苔藓纤维发芽。小脑回周围异常兴奋性突触环路和海马CA3区苔藓纤维发芽形成推测是局灶性皮质发育障碍导致癫痫发生的重要机制。

Microgyrus morphology and hippocampal mossy fiber sprouting in rats with focal cortical dysplasia

Objective To find out microgyrus morphology and hippocampal mossy fiber sprouting in adult rat with cortical dysplasia induced by focal liquid nitrogen injury. Methods 30 newborn Wistar rats were randomly but evenly into 3 groups: control group, sham-operated group, liquid nitrogen injury group. A copper probe of diameter 1 mm was cooled with liquid nitrogen and put for 8 seconds on the exposed calvarium above the primary parietal cortex in the third group that was narcotic under a low temperature. Freeze-lesioned and sham-operated and normal rats were feed to survive for 16-18 weeks. We observed the microgyrus morphology change with naked eyes and under a light microscope, and assessed the hippocampal mossy fiber sprouting after HE staining, Nissl staining and Timm's histochemical method. The comparisons between every two groups were performed with Nemenyi method. Results All freeze-lesioned rats displayed typical cortical malformations consisting of a longitudinal microgyrus. There are mossy fiber sprouting in hippocampal CA3 region ipsilaterally, but no mossy fiber sprouting in sham-operated or normal rats (nonparametric Kruskal-Wallis H test and Nemenyi test). Conclusion Neonatal liquid nitrogen injury could result in mossy fiber sprouting in hippocampal CA3 region and microgyrus. The study provides important mechanisms of epileptogenicity because of mossy fiber sprouting in hippocampal CA3 region and hyperexcitability of the cortical synapse network adjacent to the experimental microgyrus.