Thymoquinone ameliorates symptoms of Parkinson's disease in a 6-OHDA rat model by downregulation of miR-204-3p.

microRNAs (miRNAs) play a significant role in the pathophysiology of Parkinson's disease. In this study, we evaluated the neuroprotective effect of thymoquinone on the expression profiles of miRNA and cognitive functions in the 6-hydroxydopamine (6-OHDA)-induced Parkinson's model. Male adult Wistar albino rats (200-230 g, n  = 36) were randomly assigned to six groups: Sham, thymoquinone (10 mg/kg, p.o.), 6-OHDA, 6-OHDA + thymoquinone (10 mg/kg), 6-OHDA + thymoquinone (20 mg/kg), and 6-OHDA + thymoquinone (50 mg/kg). Behavioral changes were detected using the open field and the elevated plus maze tests. The mature 728 miRNA expressions were evaluated by miRNA microarray (GeneChip miRNA 4.0). Ten miRNAs were selected (rno-miR-212-5p, rno-miR-146b-5p, rno-miR-150-5p, rno-miR-29b-2-5p, rno-miR-126a-3p, rno-miR-187-3p, rno-miR-34a-5p, rno-miR-181d-5p, rno-miR-204-3p, and rno-miR-30c-2-3p) and confirmed by real-time PCR. Striatum samples were stained with hematoxylin-eosin to determine the effect of dopaminergic lesions. One-way ANOVA test and independent sample t -test were used for statistical analyses. rno-miR-204-3p was upregulated at 6-OHDA and downregulated at the 50 mg/kg dose of thymoquinone. In conclusion, thymoquinone at a dose of 50 mg/kg ameliorates symptoms of Parkinson's disease in a 6-OHDA rat model by downregulation of miR-204-3p. Also, the results showed that thymoquinone can improve locomotor activity and willing exploration and decreased anxiety. Therefore, thymoquinone can be used as a therapeutic agent.

Downregulatory effect of miR-342-3p on epileptogenesis in the PTZ-kindling model.

BACKGROUND: Epileptogenesis is a process that results in neurons firing abnormally, causing seizures. Increasing evidence has shown that miRNAs expressed in the epileptic hippocampus are involved in epileptogenesis. We demonstrated the expression changes of miRNAs that may be effective in epileptogenesis in silico analysis in the kindling model created with Pentylenetetrazole (PTZ). Thus, we aimed to identify the target genes responsible for epileptogenesis. METHODS AND RESULTS: Fifteen male Wistar-albino rats (200-230 g) were randomly divided into two groups control (n = 6) and PTZ (n = 9). The control group received 0.5 ml saline, and the PTZ group (35 mg/kg i.p.) intraperitoneally (i.p.) (11 times, every other day) to induce tonic-clonic seizures. Seizures were observed and scored 30 min after PTZ injection. After the last dose of PTZ (75 mg/kg) administration, the hippocampus tissues of the rats were removed by anesthesia. Analysis of miRNAs was performed with the Affymetrix gene chip miRNA sequence (728 miRNA) and confirmed by the Real-Time Polymerase Chain Reaction (Real-Time PCR) method (29 miRNAs). We evaluated the expression change of the target gene of miRNA, whose expression change was detected using in silico analysis, by q-RT PCR. Eight miRNAs with changes in expression were detected. Of these miRNAs, miR-342-p was downregulated in the PTZ group and was statistically significant (p < 0.005). Ultimately, we determined that the target gene of miR-342-p is a metabotropic glutamate receptor 2 (GRM2) and that GRM2 expression is upregulated. CONCLUSIONS: Downregulation of miR-342-3p in the PTZ kindling model may result in the upregulation of GRM2.

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. rno-miR-182 and rno-miR-27b-3p 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.