MiR-15a attenuates peripheral nerve injury-induced neuropathic pain by targeting AKT3 to regulate autophagy

Abstract

Objective: Aim of this study was to detect the expression of miR-15a in rats following chronic constriction injury (CCI) and to investigate the regulatory functions of miR-15a during neuropathic pain (NP) development.

Methods: CCI was performed in adult Sprague-Dawley rats to set up the rat model of neuropathic pain. MiR-15a agomir and scrambled control were delivered into the implanted catheter of rats. The mechanical allodynia and thermal hyperalgesia were assessed in both CCI- and sham-operated groups. Rat lumbar spinal cord tissues were harvested for mRNA and protein analyses. The primary spinal microglia were isolated from adult Sprague-Dawley rats and transfected with miR-15a mimics, scramble miRNA, miR-15a inhibitor or its corresponding negative control. Cell lysates were collected for mRNA and protein analyses.

Results: Compared to sham-operated group, the expression of miR-15a in CCI rats was significantly reduced, whereas neuroinflammation in spinal cord tissues was increased. Intrathecal administration of miR-15a agomir significantly attenuated CCI-induced NP and the levels of proinflammatory cytokines, including IL-6, IL-1β, and TNF-α. AKT3 was predicted and confirmed as a miR-15a-regulated gene. We further demonstrated that miR-15a overexpression downregulated the level of AKT3 in primary rat microglia and rat CCI model. Moreover, the upregulation of miR-15a induced the expressions of autophagy-associated proteins, suggesting that the regulation mechanism of miR-15a in NP development involves AKT3-mediated autophagy via inhibiting the expression of AKT3.

Conclusion: Our findings indicated that miR-15a might serve as a promising therapeutic target for the management of NP through the stimulation of autophagic process.

Keywords: AKT3; Autophagy; Chronic constriction injury; Neuropathic pain; miR-15a.