Objective: To observe the expression of cyclin-dependent kinase 5 (Cdk5) and p35 in rat 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 3rd day, 1st week, 2nd week, 4th week, and 6th week after daily injection, Timm staining was performed in area CA3 and dentate gyrus, and the mRNA and protein of Cdk5 and p35 were analyzed in the hilus and stratum granulosum of dentate gyrus and area CA1 and CA3 of hippocampus, by in situ hybridization and immunohistochemistry, respectively.
Results: The expression levels of Cdk5 and p35 mRNA were significantly higher in the PTZ treated subgroups of the 3rd day, 1st week, 2nd 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 to approximately 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.