Deficit of Kcnma1 mRNA expression in the dentate gyrus of epileptic rats

Abstract

Epileptogenesis in mesial temporal lobe epilepsy is determined by several factors including abnormalities in the expression and function of ion channels. Here, we report a long-lasting deficit in gene expression of Kcnma1 coding for the large-conductance calcium-activated potassium (BK, MaxiK) channel alpha-subunits after pilocarpine-induced status epilepticus. By using comparative real-time PCR, Taqman gene expression assays, and the delta-delta comparative threshold method we detected a significant reduction in Kcnma1 expression in microdissected dentate gyrus at different intervals after status epilepticus (24 h, 10 days, 1 month, and more than 2 months). BK channels are key regulators of neuronal excitability and transmitter release. Hence, defective Kcnma1 expression may play a critical role in the pathogenesis of mesial temporal lobe epilepsy.

Fig. 1

Analysis of Kcnma1 gene expression after pilocarpine-induced status epilepticus (SE). (a). Real-time RT-PCR analysis was performed for normalizing control gene (Gapdh) and targeted gene Kcnma1 using the ÄÄCT method. Amplification plots of triplicates are shown for representative experiments from four groups of pilocarpine-treated epileptic rats (amplification curve indicated by arrow) sacrificed at different time points after SE versus controls as follows: 24 h: A1, 10 days: A2; 1 month: A3 and more than 2 months, A4. ΔCT=CT_Control−CT_Epileptic for Kcnma1 at threshold, ÄRn, change in fuorescence. (b) Graph representation of relative changes in gene expression of Kcnma1 after pilocarpine-induced status epilepticus. Data presented as mean±SEM. Statistical analysis by ANOVA was significant P<0.001. Post-hoc least significant difference comparisons relative to controls, *P<0.05, **P<0.01, ***P<0.001.