Pentylenetetrazole-induced kindling rat model: miR-182 and miR-27b-3p mediated neuroprotective effect of thymoquinone in the hippocampus.

Objectives: Epilepsy is a neurological disease that pathologically affects brain functions. The epileptic hippocampus has modified microRNA(miRNA) levels. Therefore, we aimed to evaluate the neuroprotective effect of thymoquinone (TQ) in PTZ-induced epilepsy and to demonstrate the overlap between miRNA and mRNA expression profiles.

Methods: Male adult Wistar albino rats (200-230 g, n = 20) were divided into three groups as control (n = 6), PTZ (n = 7), and TQ + PTZ (n = 7). The PTZ kindling model was created by injecting PTZ in sub convulsive doses to rats on days 1, 3, 5, 8, 10, 12, 15, 17, 19, 22, and 24 of the study into animals. Clonic and tonic seizures were induced by injecting a convulsive dose of PTZ on day 26 of the study. Rats in the TQ+PTZ group were treated by oral gavage with a 20 mg/kg TQ 2 h before each PTZ injection. The rats in the control group were treated with 0.5 ml saline. Seizure severity was evaluated with the Racine scale. The genes and signaling pathways targeted by miRNAs were determined by bioinformatics analysis.

Results: In the rat hippocampus, mature 728 miRNAs were analyzed by microarray and the nine miRNA were verified by quantitative Real-Time PCR. and were up-regulated in the PTZ group and down-regulated in the TQ + PTZ group.

Discussion: In the PTZ kindling epilepsy model, the expression of these two miRNAs was regulated by TQ and exerted a neuroprotective effect by controlling the activities of target genes.