Electroacupuncture Inhibits Autophagy of Neuron Cells in Postherpetic Neuralgia by Increasing the Expression of miR-223-3p.

Postherpetic neuralgia (PHN) is a complication of herpes zoster viral infection. Its main manifestations are continuous or intermittent burning-like and electroshock-like pain in the affected nerves. Electroacupuncture (EA) is widely used in clinical treatment and exerts effects in alleviating neuropathic pain. In this study, we investigated the effect and underlying mechanism of EA on PHN. Sprague-Dawley rats were treated with resiniferatoxin (RTX) to establish a PHN model and subjected to EA and/or miR-223-3p overexpression (OV) or interference. Mechanical withdrawal latency was measured as an indication of pain sensitivity. Hematoxylin-eosin staining and transmission electron microscopy were performed to observe neuron cell morphology and autophagic vacuoles, respectively. ELISA was performed to detect reactive oxygen species (ROS) production and the levels of tumor necrosis factor- (TNF-) α, inducible nitric oxide synthase (iNOS), interleukin- (IL-) 6, and IL-10. Changes in autophagy and apoptosis-related miRNAs were detected by immunofluorescence and qRT-PCR, respectively. In RTX-treated rats, OV and EA reduced pain sensitivity, decreased the number of eosinophils, and increased that of nerve cells. ROS generation and the levels of TNF-α and iNOS were significantly reduced, while those of IL-6 and IL-10 were increased. OV and EA induced fewer autophagic vacuoles than those in the model group. The expression of autophagy-related protein microtubule-associated protein 1 light chain 3-II, ATG9, and Rab1 was decreased by OV and EA, whereas that of P62 was increased. qRT-PCR revealed that miR-223-3p expression in the model group decreased but was increased by EA. EA inhibits neuron cell autophagy in PHN by increasing miR-223-3p expression.

Deep Sequencing Identification of Differentially Expressed miRNAs in the Spinal Cord of Resiniferatoxin-Treated Rats in Response to Electroacupuncture.

Electroacupuncture (EA) is an effective treatment to relieve pain in patients with postherpetic neuralgia. However, the mechanisms of EA involved therein are still unknown. We first injected resiniferatoxin (RTX) into Sprague Dawley rats to construct the neuralgia model. One week after injection, the rats were treated with EA at the "Huantiao" (GB30) and "Yanglingquan" (GB34) acupoints for 5 weeks. Nociceptive behavioral tests were performed to analyze the changes in thermal sensitivity and mechanical allodynia after RTX induction and EA treatment. Deep sequencing was performed to identify differentially expressed miRNAs in the spinal cord of RTX-induced rats in response to EA treatment. The nociceptive behavioral tests showed that EA at the left GB30 and GB34 acupoints significantly reduced RTX-induced tactile sensitivity and increased RTX-inhibited thermal sensitivity. The sequencing data indicated that RTX resulted in one upregulated and five downregulated miRNAs, and EA treatment resulted in two upregulated miRNAs. Furthermore, seven upregulated and two downregulated miRNAs were found between rats subjected to EA and sham operation. Functional analysis suggested that the targets of differentially expressed miRNAs were enriched in many nervous system-related pathways. The pathway-gene-miRNA net analysis showed that miR-7a-5p had the most target genes. Moreover, miR-233-3p was downregulated after RTX injection and upregulated by EA treatment. We speculated that the upregulation of miR-7a-5p and miR-233-3p is involved in the analgesic effects of EA. Our analysis on the EA-induced differential expression of miRNAs provides novel insights into the mechanisms of EA analgesia in postherpetic neuralgia.