To investigate the effect of miR-186-5p regulation of the silent information regulator 1/peroxisome proliferator-activated receptor γ coactivator-1α/fibronectin type Ⅲ domain-containing protein 5 (SIRT1/PGC-1α/FNDC5) pathway on the neurological function of mice with ischemic stroke (IS).

An IS mouse model was established using the middle cerebral artery occlusion (MCAO) method, and mice were divided into five groups: model group, negative control group, miR-186-5p inhibitor group, edaravone group, and miR-186-5p inhibitor + SIRT1 inhibitor (EX527) group, with 10 mice in each group. Additionally, 10 mice were used as a sham operation group, undergoing the same procedures as the IS model group except for the absence of filament insertion. The neurological function was evaluated using the Longa scoring system; the condition of nerve injury was observed by hematoxylin-eosin and Nissl staining; the expression of neuron-specific nuclear protein (NeuN) and ionized calcium-binding adapter molecule 1 (Iba-1) was analyzed by immunofluorescence; the expression levels of miR-186-5p and Sirt1 mRNA were detected by reverse transcription polymerase chain reaction; the expression levels of proteins related to the SIRT1/PGC-1α/FNDC5 pathway were detected by Western blotting; and the targeting relationship was verified by dual-luciferase reporter assay. The independent samples t-test was used to compare the measurement data between the two groups; one-way ANOVA was used to compare the measurement data among multiple groups, and the SNK-q test was used for further pairwise comparisons.

The Longa scores of the miR-186-5p inhibitor group, the edaravone group, the miR-186-5p inhibitor + EX527 group, the negative control group, the model group, and the sham operation group were 0.86±0.10, 0.82±0.10, 1.85±0.22, 2.09±0.23, 2.15±0.26, and 0±0, respectively; the relative expression levels of SIRT1 protein were 0.77±0.08, 0.81±0.09, 0.49±0.05, 0.51±0.06, 0.48±0.05, and 0.85±0.10, respectively; the relative expression levels of PGC-1α protein were 0.51±0.06, 0.59±0.06, 0.33±0.04, 0.29±0.03, 0.24±0.03, and 0.61±0.07, respectively; the relative expression levels of FNDC5 protein were 1.11±0.12, 1.18±0.12, 0.71±0.08, 0.69±0.08, 0.61±0.07, and 1.24±0.13, respectively. The differences in the above indicators between the miR-186-5p inhibitor group and the negative control group were statistically significant (q=22.519, 11.070, 13.688, 12.921; all P＜0.001). The differences in the above indicators between the miR-186-5p inhibitor + EX527 group and the miR-186-5p inhibitor group were also statistically significant (q=18.125, 11.921, 11.199, 12.305; all P＜0.001). The number of NeuN-positive cells, the relative expression level of Sirt1 mRNA, and the number of nerve cells in the model group were significantly lower than those in the sham operation group, and the number of Iba-1-positive cells and the relative expression level of miR-186-5p in the model group were significantly higher than those in the sham operation group (all P＜0.05). The number of NeuN-positive cells, the relative expression level of Sirt1 mRNA, and the number of nerve cells in the miR-186-5p inhibitor group and the edaravone group were significantly higher than those in the negative control group, while the number of Iba-1-positive cells and the expression level of miR-186-5p were significantly lower than those in the negative control group (all P＜0.05). The number of NeuN-positive cells, the relative expression level of Sirt1 mRNA, and the number of nerve cells in the miR-186-5p inhibitor + EX527 group were significantly lower than those in the miR-186-5p inhibitor group, while the number of Iba-1-positive cells was significantly higher than that in the miR-186-5p inhibitor group (all P＜0.05).

Inhibition of miR-186-5p expression improves neurological function in IS mice, and the underlying mechanism is associated with targeted regulation of the SIRT1/PGC-1α/FNDC5 signaling pathway.