• Song Zhang, Xiao-Na Yang, Ting Zang, Jun Luo, Zhiqiang Pan, Lei Wang, He Liu, Di Liu, Yan-Qiang Li, Yao-Dong Zhang, Hongxing Zhang, Hai-Lei Ding, and Jun-Li Cao.
• From Jiangsu Province Key Laboratory of Anesthesiology, Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University (S.Z., X.-N.Y., T.Z., J.L., Z.P., L.W., H.L., D.L., Y.-Q.L., Y.-D.Z., H.Z., H.-L.D., J.-L.C.) and Department of Anesthesiology, The Affiliated Hospital of Xuzhou Medical University (H.L., J.-L.C.), Xuzhou, China.
• Anesthesiology. 2017 Sep 1; 127 (3): 548-564.

BackgroundThe authors previously reported that noncoding microRNA miR-219-5p is down-regulated in the spinal cord in a nociceptive state. The ventral tegmental area also plays critical roles in modulating nociception, although the underlying mechanism remains unknown. The authors hypothesized that miR-219-5p in the ventral tegmental area also may modulate nociception.MethodsThe authors studied the bidirectional regulatory role of ventral tegmental area miR-219-5p in a rat complete Freund's adjuvant model of inflammatory nociception by measuring paw withdrawal latencies. Using molecular biology technologies, the authors measured the effects of astroglial coiled-coil and C2 domain containing 1A/nuclear factor κB cascade and dopamine neuron activity on the down-regulation of ventral tegmental area miR-219-5p-induced nociceptive responses.ResultsMiR-219-5p expression in the ventral tegmental area was reduced in rats with thermal hyperalgesia. Viral overexpression of ventral tegmental area miR-219-5p attenuated complete Freund's adjuvant-induced nociception from 7 days after complete Freund's adjuvant injection (paw withdrawal latencies: 6.09 ± 0.83 s vs. 3.96 ± 0.76 s; n = 6/group). Down-regulation of ventral tegmental area miR-219-5p in naïve rats was sufficient to induce thermal hyperalgesia from 7 days after lentivirus injection (paw withdrawal latencies: 7.09 ± 1.54 s vs. 11.75 ± 2.15 s; n = 8/group), which was accompanied by increased glial fibrillary acidic protein (fold change: 2.81 ± 0.38; n = 3/group) and reversed by intraventral tegmental area injection of the astroglial inhibitor fluorocitrate. The nociceptive responses induced by astroglial miR-219-5p down-regulation were inhibited by interfering with astroglial coiled-coil and C2 domain containing 1A/nuclear factor-κB signaling. Finally, pharmacologic inhibition of ventral tegmental area dopamine neurons alleviated this hyperalgesia.ConclusionsDown-regulation of astroglial miR-219-5p in ventral tegmental area induced nociceptive responses are mediated by astroglial coiled-coil and C2 domain containing 1A/nuclear factor-κB signaling and elevated dopamine neuron activity.

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