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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.

1. The aim of the present study was to investigate the effect of hydrogen sulphide (H(2)S) on cobalt chloride (CoCl(2))-induced injury in H9c2 embryonic rat cardiac cells. 2. After 36 h incubation in the presence of 600 micromol/L CoCl(2), reduced cell viability of H9c2 cells was observed, as well as the induction of apoptosis. In addition, CoCl(2) (600 micromol/L) enhanced the production of reactive oxygen species (ROS) and the expression of cleaved caspase 3, induced a loss of mitochondrial membrane potential (MMP) and decreased reduced glutathione (GSH) production. These results suggest that CoCl(2) induces similar responses to hypoxia/ischaemia. 3. Pretreatment of cells with 400 micromol/L NaHS (a H(2)S donor) for 30 min prior to exposure to CoCl(2) (600 micromol/L) significantly protected H9c2 cells against CoCl(2)-induced injury. Specifically, increased cell viability and decreased apoptosis were observed. In addition, NaHS pretreatment blocked the CoCl(2)-induced increases in ROS production and cleaved caspase 3 expression, as well as the decreases in GSH production and loss of MMP. 4. Pretreatment of cells with 2000 micromol/L N-acetylcysteine (NAC), a ROS scavenger, for 1 h prior to CoCl(2) exposure significantly protected H9c2 cells against CoCl(2)-induced injury, specifically enhancing cell viability, decreasing ROS production and preventing loss of MMP. 5. The findings of the present study suggest that H(2)S protects H9c2 cells against CoCl(2)-induced injury by suppressing oxidative stress and caspase 3 activation.