戊四氮点燃模型大鼠海马苔藓纤维出芽与Cdk5／p35表达的动态变化

Hippocampal mossy fiber sprouting and Cdk5/p35 expressions in the pentylenetetrazole kindling rat model

目的:动态观察细胞周期素依赖性激酶5(cyclin-dependent kinase 5,Cdk5)和调节亚基p35在戊四氮(pentylenetetrazole,PTZ)致痫大鼠海马各区的表达变化,及其与苔藓纤维出芽(mossy fiber sprouting,MFS)的关系,以探讨其在癫痫发病机制中的作用。方法:SD雄性成年大鼠120只,随机分为PTZ组和对照组;PTZ组分为PTZ第1次注射后3 d、1周、2周、4周、6周共5个亚组,每亚组12只,对照组随机分为5个亚组,与PTZ组各时间点对应。以上各亚组再分2个小组,每小组6只大鼠,分别进行(1)免疫组织化学和原位杂交,检测各时间点Cdk5与p35蛋白和mRNA在海马CA1和CA3区、齿状回颗粒细胞层和门区的表达;(2)Timm染色并评分。结果:PTZ组大鼠上述各区Cdk5和p35 mRNA在第3天时表达即有明显上调(P<0.01),第4周仍维持在较高水平,第6周时基本恢复到对照组水平;各区Cdk5和p35蛋白表达从第3天起即上调(P<0.01),第2周时最强,其后下调,至第6周接近或达到对照组水平。PTZ组CA3区在点燃前MFS评分1～4分,点燃后MFS评分4～5分。MFS的变化趋势与Cdk5和p35的表达一致。结论:海马Cdk5/p35的表达变化可能参与苔藓纤维出芽,从而促进癫痫的发生。

Objective To observe the expression of cyclin-dependent kinase 5 （Cdk5） and p35 in rats＇ hippocampus during pentetrazole kindling process and their relation with mossy fiber sprouting （ MFS ） , and to investigate the role of Cdk5/p35 in epileptogenesis. Methods Altogether 120 healthy male SD rats were randomly divided into a control group and a pentylenetetrazole （PTZ） treated group. The epileptic models were established by the injection of PTZ intraperitoneally while the control rats were injected with an equal dose of saline. At the 3 rd day, 1 st week, 2nd week,4th week, and gyms, and the sum of dentate histochemistry, 6th week after daily injection, Timm staining was performed in area CA3 and dentate mRNA and protein of Cdk5 and p35 were analyzed in the hilus and stratum granulogyrus and area CA1 and CA3 of hippocampus, by in situ hybridization and immunorespectively. Results The expression levels of Cdk5 and p35 mRNA were significantly higher in the PTZ treated subgroups of the 3 rd day, 1 st week, 2 nd week, and 4th week than those in the controls. Thereafter, the expression decreased to the level of controls. The expression level of Cdk5 and p35 protein increased from the 3rd day to 2nd week, and then gradually decreased to the level of the controls. Timm scores for PTZ groups were 1 - 4 before kindling and 4-5 after kindling in area CA3. Conclusion Change of Cdk5/p35 expression in the hippocampus may play a role in epileptogenesis by influencing the process of mossy fiber sprouting.