Intradermal miR-16–5p targets Akt3 and reduces RTX-induced postherpetic neuralgia-mimic pain in mice

The molecular mechanisms of refractory pain in postherpetic neuralgia (PHN) patients are not fully understood. PHN may be related to skin abnormality after herpes zoster induced skin lesions. We previously reported 317 differentially expressed microRNAs (miRNAs) in PHN skin compared with the contralateral normal mirror skin. In this study, 19 differential miRNAs were selected and the expression was validated in other 12 PHN patients. The expression levels of miR-16-5p, miR-20a-5p, miR-505-5p, miR-3664-3p, miR-4714-3p and let-7a-5p are lower in PHN skin, which is the same as those in microarray experiment. To evaluate the effects of cutaneous miRNA on PHN, the expression of candidate miRNAs is further observed in resiniferatoxin (RTX) induced PHN-mimic mice model. In the plantar skin of RTX mice, miR-16-5p and let-7a-5p are downregulated, with the same expression trend of PHN patients. In addition, intraplantar injection of agomir-16-5p reduced mechanical hyperalgesia, and improved thermal hypoalgesia in RTX mice. Furthermore, agomir-16-5p down-regulated the expression levels of Akt3, which is the target gene of agomir-16-5p. These results suggest that intraplantar miR-16-5p may alleviate RTX induced PHN-mimic pain by inhibiting the expression of Akt3 in the skin.