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.

中文翻译：

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MiR-15a通过靶向AKT3调节自噬来减轻周围神经损伤引起的神经性疼痛。

这项研究的目的是检测慢性压迫性损伤（CCI）后大鼠中miR-15a的表达，并研究miR-15a在神经性疼痛（NP）发生过程中的调节功能。方法在成年的Sprague-Dawley大鼠中进行CCI，以建立神经性疼痛的大鼠模型。将MiR-15a agomir和加扰的对照递送到大鼠的植入导管中。在CCI和假手术组均评估了机械性异常性疼痛和热痛觉过敏。收获大鼠腰脊髓组织用于mRNA和蛋白质分析。从成年Sprague-Dawley大鼠中分离出初级脊髓小胶质细胞，并用miR-15a模拟物，加扰的miRNA，miR-15a抑制剂或其相应的阴性对照转染。收集细胞裂解物用于mRNA和蛋白质分析。结果与假手术组相比，miR-15a在CCI大鼠中的表达明显减少，而脊髓组织中的神经炎症增加。鞘内注射miR-15a agomir可显着减弱CCI诱导的NP和促炎细胞因子（包括IL-6，IL-1β和TNF-α）的水平。AKT3被预测并确认为miR-15a调控基因。我们进一步证明，miR-15a过表达下调了原代大鼠小胶质细胞和大鼠CCI模型中AKT3的水平。此外，miR-15a的上调诱导了自噬相关蛋白的表达，这表明miR-15a在NP发育中的调控机制通过抑制AKT3的表达而涉及AKT3介导的自噬。