发育鼠反复惊厥脑损伤后海马神经元可塑性研究

Hippocamus neuroplasticity in immature rats following recurrent seizure injury

目的观察幼鼠反复惊厥后海马组织病理学改变,探讨幼鼠急性损伤后神经元的可塑性。方法用戊四氮(pentylenetetrazol,PTZ)对生后10d(P10)Wistar。鼠反复腹腔注射5 d,制成反复惊厥模型,设生理盐水对照组;采用硫堇染色对CA1、CA3、DG及门区神经元进行细胞计数;免疫组化技术检测惊厥发作24h后NF-κB的表达;Timm组织化学染色观察苔藓纤维发芽并评分。结果①海马CA1、CA3区神经元计数实验组与对照比较差异无统计学意义(P>0．05),齿状回DG区颗粒细胞数实验组(23．25±3．05)较对照组(16．25±1．58)增多(P<0．05)。②海马CA1、CA3及DG区NF-κB光密度值较对照组高(P<0．05)。⑨实验组CA3区苔藓纤维发芽评分(1．50±0．92)明显高于对照组(0．25±0．46,P<0．01)。结论幼鼠急性惊厥性脑损伤后海马齿状同颗粒细胞增生、苔藓纤维发芽是发育脑急性损伤神经可塑性的有力佐证,其中NF-κB表达增加起一定作用。

Objectives To observe histopathological changes thus understanding the neuroplasticity in immature rat hippocampus following recurrent seizure injury. Methods Rats at postnatal day 10 in = 48） were divided into 2 groups： the control group in = 18） treated daily with normal saline for ,5 consecutive days, and experimental group in = 30） treated with daily administration of pentylenetetrazol （PTE） for 5 consecutive days to induce recurrent convulsions. The neurons in dentate granule area, CA1, CA3, as well as in hilar were stained with thionin and counted to study the profile of necrosis and apoptosis. Timm＇ s method of silver sulfide staining was adopted to observe the mossy fiber sprouting two weeks after the last spell of seizures. Expression of NF-κB was examined by immunohistochemistry at 24 hours after the last spell of seizures. Results Cell counting of CA1, CA3 and hilar neurons demonstrated no differences from that of the controls （P 〉 0.05）, whereas neurons in dentate granule increased significantly with comparison to control （23.25 ± 3.06 vs 16.25 ± 1.58, P 〈 0.05） . More expression of NF-κB was observed in CA1, CA3 and dentate granule cells 24 hours later after PTZ-kindling than that of the controls （P 〈 0.05）. The mossy fiber sprouting in the CA3 was significantly increased in the neonatal rats in experimental group comparing with that of the controls （1.50 ± 0.92 vs 0.25 ± 0.46, P 〈 0.01 ）. Conclusions No cell loss was seen in hippocampus of neonatal rats after recurrent kindling. The high expression of NF-κB could be putatively one of the important molecular bases underlying the special resistance of the neurons in premature brain to the epileptic cerebral lesions. Neurons of dentate granule increased significantly after recurrent seizures, which seemed to be the initial mechanism for mossy fiber sprouting in immature rats.