Circular RNAs are non-coding RNAs, and are enriched in the CNS. Dorsal horn neurons of the spinal cord contribute to pain-like hypersensitivity after nerve injury in rodents. Here we show that spinal nerve ligation is associated with an increase in expression of circAnks1a in dorsal horn neurons, in both the cytoplasm and the nucleus. Downregulation of circAnks1a by siRNA attenuates pain-like behaviour induced by nerve injury. In the cytoplasm, we show that circAnks1a promotes the interaction between transcription factor YBX1 and transportin-1, thus facilitating the nucleus translocation of YBX1. In the nucleus, circAnks1a binds directly to the Vegfb promoter, increases YBX1 recruitment to the Vegfb promoter, thereby facilitating transcription. Furthermore, cytoplasmic circAnks1a acts as a miRNA sponge in miR-324-3p-mediated posttranscriptional regulation of VEGFB expression. The upregulation of VEGFB contributes to increased excitability of dorsal horn neurons and pain behaviour induced by nerve injury. We propose that circAnks1a and VEGFB are regulators of neuropathic pain.

BackgroundStudies showed that upregulation of Nav1.6 increased the neuronal excitability and participated in neuropathic pain in the dorsal root ganglion (DRG). However, the molecular mechanisms underlying Nav1.6 upregulation were not reported yet.MethodsThe paw withdrawal threshold was measured in the rodents following lumbar 5 ventral root transection (L5-VRT). Then qPCR, western blotting, immunoprecipitation, immunohistochemistry, and chromatin immunoprecipitation assays were performed to explore the molecular mechanisms in vivo and in vitro.ResultsWe found that the levels of Nav1.6 and phosphorylated STAT3 were significantly increased in DRG neurons following L5-VRT, and TNF-α incubation also upregulated the Nav1.6 expression in cultured DRG neurons. Furthermore, immunoprecipitation and chromatin immunoprecipitation assays demonstrated that L5-VRT increased the binding of STAT3 to the Scn8a (encoding Nav1.6) promoter and the interaction between STAT3 and p300, which contributed to the enhanced transcription of Scn8a by increasing histone H4 acetylation in Scn8a promoter in DRG. Importantly, intraperitoneal injection of the TNF-α inhibitor thalidomide reduced the phosphorylation of STAT3 and decreased the recruitment of STAT3 and histone H4 hyperacetylation in the Scn8a promoter, thus subsequently attenuating Nav1.6 upregulation in DRG neurons and mechanical allodynia induced by L5-VRT.ConclusionThese results suggested a new mechanism for Nav1.6 upregulation involving TNF-α/STAT3 pathway activation and subsequent STAT3-mediated histone H4 hyperacetylation in the Scn8a promoter region in DRG, which contributed to L5-VRT-induced neuropathic pain.

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Objectives. Carpal tunnel syndrome (CTS) is one of the most common nerve entrapment syndromes, which has a serious impact on patients’ work and life. The most effective conservative treatment is steroid injection but its long-term efficacy is still not satisfactory. The aim of this study was to evaluate the effectiveness of steroid injection combined with miniscalpel-needle (MSN) release for treatment of CTS under ultrasound guidance versus steroid injection alone. We hypothesized that combined therapy could be more beneficial. Methods. Fifty-one patients with CTS were randomly allocated into two groups, namely, steroid injection combined with MSN release group and steroid injection group. The therapeutic effectiveness was evaluated using Boston Carpal Tunnel Questionnaire (BCTQ), cross-sectional area (CSA) of the median nerve, and four electrophysiological parameters, including distal motor latency (DML), compound muscle action potential (CMAP), sensory nerve action potential (SNAP), and sensory nerve conduction velocity (SNCV) at baseline, 4 and 12 weeks after treatment. Results. Compared with baseline, all the parameters in both groups showed statistically significant improvement at week 4 and week 12 follow-up, respectively (P<0.05). When compared with steroid injection group, the outcomes including BCTQ, DML, CMAP, SNCV, and CSA of the median nerve were significantly better in steroid injection combined with MSN release group at week 12 after treatment (P<0.05). Conclusions. The effectiveness of steroid injection combined with MSN release for CTS is superior to that of steroid injection alone, which may have important implications for future clinical practice. This Chinese clinical trial is registered with ChiCTR1800014530.