MiR-106b-5p represses neuropathic pain by regulating P2X4 receptor in the spinal cord in mice

Background: P2X 4 receptor (P2X 4 R)-mediated spinal microglial activation makes a critical contribution to pathologically enhanced pain processing in the dorsal horn. It can be upregulated under conditions of neuropathic pain. However, the specific mechanism of pathogenesis and potential molecular targets has not yet been made explicit. MicroRNAs (miRNAs) are commonly recognized as indicators in neuropathic pain pathophysiology. Methods: : We established the pain model of spared nerve injury (SNI), and the 50% paw withdrawal thresholds (PWMTs) were used to assess behavior of mouse. MiRNA expression profiling was performed to detect differential expressed miRNA. The western-bolt and quantitative real time PCR to examine P2X4R and miRNA expression in the mouse. Dual-luciferase reporter assays confirmed the correlation between P2X4R and miRNA. Fluorescence in situ hybridization was used to show location between P2X4R and miRNA. Results: : In the present study, we found that P2X 4 R was up-regulated in the spinal dorsal horn of mice following spared nerve injury (SNI), and we identified 69 miRNAs (46 up-regulated and 23 down-regulated miRNAs) were differently expressed (fold change > 2, P < 0.05). P2X 4 R was a major target of miR-106b-5p (one of down-regulated miRNAs in SNI) with bioinformatics technology and quantitative real time PCR analysis validated the expressed change of miR-106b-5p, and dual-luciferase reporter assays confirmed the correlation between them. Fluorescence in situ hybridization showed that miR-106b-5p was co-localized with P2X 4 R in the spinal cord. Transfection with miR-106b-5p mimic on BV2 cells reversed the up-regulation of P2X 4 R induced by LPS. Moreover, miR-106b-5p overexpression significantly attenuated neuropathic pain induced by SNI, with decreased expression of P2X 4 R mRNA and protein in the spinal cord. Conclusion: Taken together, our results suggest that miR-106b-5p can serve as an important regulator of neuropathic pain development by targeting P2X 4 R.