microRNA changes in the dorsal horn of the spinal cord of rats with chronic constriction injury: A TaqMan® Low Density Array study

Elucidation of the mechanisms underlying neuropathic pain is expected toaid in the discovery and selection of effective therapeutic methods. Currently,microRNA (miRNA) is thought to play an important role in the development and maintenanceof the nervous system. We, therefore, hypothesized that miRNAs are involved inneuropathic pain, and investigated this possibility by analyzing miRNA expressionin the dorsal horn of the spinal cord in a chronic constriction injury (CCI) ratmodel using the TaqMan® Low Density Array (TLDA). Neuropathic pain model ratswere produced by CCI induced by ligation of the sciatic nerve. The miRNA expressionin the dorsal horn of the spinal cord was analyzed in Day 0 rats, with no sciaticnerve ligation or sham operation, Day 7 rats, examined 7 days after sciatic nerveligation or sham operation, and Day 14 rats, examined 14 days after sciatic nerveligation or sham operation using TLDA. In this study, 111 miRNAs were significantlyregulated in CCI rats in both the Day 7 and Day 14 groups compared with sham ratsin both groups. Of these 111, there were 75 miRNAs (67.6%) that had been analyzedin previous reports and 36 miRNAs (32.4%) related to the development of tumorsof the nervous system and neurodegenerative diseases. Certain miRNAs were reportedto be related to neuropathic pain; miR-500, -221 and -21. The expression levelsof a large number of miRNAs in the dorsal horn of the spinal cord in CCI ratschanged. These results provide a step toward elucidation of the mechanisms underlyingneuropathic pain.