MicroRNA-146a-5p Downregulates the Expression of P-Glycoprotein in Rats with Lithium-Pilocarpine-Induced Status Epilepticus

Increasing evidence supports that the efflux transporters, especially P-glycoprotein (P-gp), have vital roles on drug resistance in epilepsy. Overexpression of P-gp in the brain could reduce the anti-epileptic drugs (AEDs) concentration in the epileptogenic zone, resulting in drug resistance. Studies have demonstrated that recurrent seizures induce the expression of P-gp and status epilepticus (SE) could upregulate the expression of P-gp, resulting in drug resistance. MicroRNAs (miRNAs), as endogenous regulators, represent small regulatory RNA molecules that have been shown to act as negative regulators of gene expression in different biological processes. We investigated the impact of miR-146a-5p on the expression of P-gp in status epilepticus rat model. The expression of miR-146a-5p in rat cortex and hippocampus was measured by quantitative RT-PCR at 2 weeks after induction of SE. Meanwhile, we detected the expression of P-gp in the brain of SE rats using Western blotting and immunohistochemistry. Upregulation of miR-146a-5p and overexpression of P-gp were evident at 2 weeks after SE. Moreover, the expression of P-gp was downregulated by injection of miR-146a mimic into the hippocampus. We also detected the expression of interleukin-1 receptor associated protein kinases-1 (IRAK1) and tumor necrosis factor receptor-associated factor 6 (TRAF6) and nuclear factor-kappaB (NF-kappa B) p65 using Western blotting and immunohistochemistry, which indicated the expression of IRAK1, TRAF6 and NF-kappa B p-p65/p65 increased in the brain of SE rats, and overexpression of miR-146a-5p could downregulate the expression of IRAK1, TRAF6, NF-kappa B p-p65/p65 and P-gp. Our study indicated that miR-146a-5p may decrease the expression of P-gp in status epilepticus rats via NF-kappa B signaling pathway.