Demethylase <scp>FTO</scp> Regulates <scp>P2X3R</scp> Expression Contributing to the Mechanism of Hyperalgesia in Lumbar Disc Herniation

Lumbar disc herniation (LDH) is a common chronic orthopedic condition characterized by the protrusion of nucleus pulposus tissue, leading to low back and leg pain. Its pathophysiology remains poorly understood. The aim of this study was to investigate whether the demethylase Fat mass and obesity-associated protein (FTO) mediates the local translation of P2X3 receptors (P2X3R) in a rat model of LDH. The effect of this process on the excitability of dorsal root ganglion (DRG) cells was also examined, which may elucidate the peripheral molecular mechanisms underlying the specific pain sensitivity of LDH. LDH models were established in male Sprague-Dawley rats. Behavioral tests assessed mechanical and thermal pain thresholds and motor function. The expression of P2X3R and FTO in DRG was investigated by RT-qPCR, Western blot, and immunofluorescence. FTO and P2X3R were knocked down, and P2X3R methylation was examined by MeRIP to validate their roles. IL-1β and IL-6 levels were quantified by ELISA. Protein interactions were predicted using AutoDock, and DRG neuronal excitability was assessed using patch clamp recordings. Compared with the Sham group, the LDH group showed a reduction in the mechanical pain threshold of the hind limbs. There were no significant differences in motor function. IL-1β and IL-6 levels were increased in the LDH group. P2X3R and FTO expression increased in DRG, localized mainly to the cell membrane and colocalized with NeuN. Intrathecal injection of P2X3R-siRNA and FTO-siRNA was effective in increasing pain thresholds, reducing the expression of P2X3R and FTO, decreasing the excitability of neurons, and decreasing the levels of IL-1β and IL-6. RNA Methylation Immunoprecipitation (MeRIP) analysis revealed reduced m6A modification of P2X3R mRNA in the LDH group. AutoDock predicted hydrogen bond interactions between FTO and P2X3R. These findings suggest that FTO regulates local translation of P2X3R in DRG. This influences neuronal excitability and contributes to LDH-induced hyperalgesia.