MicroRNA-542-3p regulates P-glycoprotein expression in rat epilepsy via the toll-like receptor 4/Nuclear factor-kappa B signaling pathway.

Background: The function of microRNA-542-3p (miR-542-3p) in rat epilepsy is still unclear. Methods: The levels of miR-542-3p and toll-like receptor 4 (TLR4) were determined through quantitative real-time PCR. The protein levels were examined via the western blot analysis. The relationship between miR-542-3p and TLR4 was confirmed through luciferase assay. Pathological changes were analyzed via Hematoxylin-eosin (HE) and Nissl staining. Results: The rats and hippocampal cells were treated with kainic acid (KA) in vivo and in vitro. miR-542-3p was low in KA-treated rats, hippocampal cells and cerebrospinal fluid of patients with epilepsy. Further functional analysis showed that miR-542-3p overexpression inhibited KA-induced average seizure frequency, damage of hippocampal neuron and cell apoptosis, leading to the alleviation of the brain injury in epilepsy rats. miR-542-3p was determined to downregulate TLR4 expression. The relationship between miR-542-3p and TLR4 was confirmed. TLR4 knockdown reduced KA-induced nuclear factor-kappa B p65 (NF-kappa B p65), multidrug resistance 1 (MDR1), P-glycoprotein (P-gp) and apoptosis-associated protein levels. Further, for NF-kappa B p65, MDR1, P-gp and apoptosis-associated protein levels detection, miR-542-3p mimic showed a suppressive effect on these KA-induced protein levels, whereas TLR4 overexpression ameliorated the miR-542-3p-induced these protein levels in KA-treated epilepsy rats. Conclusion: We identified that miR-542-3p attenuated seizure-induced brain injury and the expression of P-gp in epilepsy rats through inhibiting TLR4/NF-kappa B signaling pathway, which might contribute to improved epilepsy therapy.