小鼠颞叶癫痫慢性期CA3区损伤对齿状回神经再生的影响

Effect of cell loss in the CA3 area on hippocampal neurogenesis in chronically epileptic mice

目的明确小鼠颞叶癫痫慢性期CA3区细胞丢失是否影响齿状回神经元新生。方法 Pilocarpine诱导制作小鼠颞叶癫痫模型,在慢性期(诱导2月后)采用BrdU标记齿状回颗粒细胞下层(subgranular zone,SGZ)新生细胞,尼氏染色将标本分为CA3区细胞部分丢失(Ⅰ型)和严重丢失(Ⅱ型)组。BrdU+NeuN免疫荧光双标染色观察新生细胞向神经元的分化,DCX和BrdU免疫荧光染色观察两组动物齿状回细胞增殖和新生细胞的存活。结果与Ⅱ型组动物比较,Ⅰ型组动物齿状回SGZ和颗粒细胞层(granule cell layer,GCL)BrdU+NeuN双标细胞数量明显增多(P<0.05),但双标细胞占BrdU免疫阳性细胞总量的比例在两组之间无统计学差异(P>0.05);Ⅰ型和Ⅱ型组动物齿状回SGZ区DCX免疫阳性神经元数量无显著性差异(P>0.05);BrdU标记6周后,Ⅰ型组动物齿状回存活的BrdU免疫阳性细胞数量较Ⅱ型组明显增多(P<0.05)。结论小鼠颞叶癫痫慢性期CA3区损伤通过影响新生细胞的存活而降低了海马齿状回神经元新生。

Objective To study the influence of cell loss in the CA3 area on hippocampal neurogenesis in mice with temporal lobe epilepsy .Methods Newly born cells in the subgranular zone （SGZ ） of dentate gyrus were labeled by the proliferation marker bromodeoxyuridine （BrdU ） at 2 months after pilocarpine‐induced status epilepticus .Double labeling of BrdU＋ NeuN was carried out to compare neuronal differentiation between type Ⅰand Ⅱ mice ,which represented partial cell loss and almost complete cell loss in the CA 3 area ,respectively .DCX and BrdU single staining were made to analyze the proliferation of progenitor cells in SGZ and the survival of the newly born cells .Results When compared with that of the type Ⅱ mice ,the number of double labeled cells of BrdU＋NeuN in the subgranular zone‐granule cell layer （SGZ‐GCL） in the type Ⅰ mice increased significantly （ P〈0 .05） .However ,the percentages of double labeled cells in all the BrdU ＋ cells were found to be similar between the two groups （P〉0 .05） .No significant difference in the number of DCX ＋ cells in SGZ was found between the typeⅠ and Ⅱ mice （P〉0 .05） .At 6 weeks after BrdU labeling ,more remaining BrdU＋ cells were found in the SGZ‐GCL in the type Ⅰ mice when compared with their counterparts in the type Ⅱ mice （P〈0 .05） .Conclusion The cell loss in the CA3 area of pilocarpine‐induced epileptic mice contributes to the declined hippocampal neurogenesis by exerting negative effects on the survival of newly born cells .