BK(Ca) Channel Inhibition by Peripheral Nerve Injury Is Restored by the Xanthine Derivative KMUP-1 in Dorsal Root Ganglia

This study explored whether KMUP-1 improved chronic constriction injury (CCI)-induced BK(Ca) current inhibition in dorsal root ganglion (DRG) neurons. Rats were randomly assigned to four groups: sham, sham + KMUP-1, CCI, and CCI + KMUP-1 (5 mg/kg/day, i.p.). DRG neuronal cells (L4–L6) were isolated on day 7 after CCI surgery. Perforated patch-clamp and inside-out recordings were used to monitor BK(Ca) currents and channel activities, respectively, in the DRG neurons. Additionally, DRG neurons were immunostained with anti-NeuN, anti-NF200 and anti-BK(Ca). Real-time PCR was used to measure BK(Ca) mRNA levels. In perforated patch-clamp recordings, CCI-mediated nerve injury inhibited BK(Ca) currents in DRG neurons compared with the sham group, whereas KMUP-1 prevented this effect. CCI also decreased BK(Ca) channel activity, which was recovered by KMUP-1 administration. Immunofluorescent staining further demonstrated that CCI reduced BK(Ca)-channel proteins, and KMUP-1 reversed this. KMUP-1 also changed CCI-reduced BK(Ca) mRNA levels. KMUP-1 prevented CCI-induced neuropathic pain and BK(Ca) current inhibition in a peripheral nerve injury model, suggesting that KMUP-1 could be a potential agent for controlling neuropathic pain.