Upregulation of
P2X3 receptor (P2X3R) has been strongly implicated in nociceptive signaling including
bone cancer pain (BCP). The present study, using rat
bone cancer model, aimed to explore the role of P2X3R in regulating rat
pain behavior under the intervention of
electroacupuncture (EA). The BCP model was successfully established by injection with MRMT-1
breast cancer cell into the medullary cavity of left tibia for 3 × 104 cells/3 μL PBS in rats as revealed by obvious bone destruction, decreased paw withdrawal thresholds (PWTs), and reduced paw withdrawal latencies (PWLs). Western blot analyses showed that P2X3R expression was significantly upregulated in ipsilateral lumbar 4-6 (L4-6) dorsal root ganglia (DRG), but the difference not seen in spinal cord dorsal horn (SCDH). With the in-depth study of P2X3R activation, we observed that
intrathecal injection of P2X3R agonist α,β-meATP aggravated MRMT-1 induced BCP, while injection of P2X3R inhibitor
A-317491 alleviated
pain. Subsequently, we demonstrated that BCP induced
mechanical allodynia and
thermal hyperalgesia were attenuated after EA treatment. Under EA treatment, total P2X3R
protein expression in ipsilateral DRGs was decreased, and it is worth mentioning that decreased expression of P2X3R
membrane protein, which indicated that both the expression and membrane trafficking of P2X3R were inhibited by EA. The immunofluorescence assay showed that EA stimulation exerted functions by reducing the expression of P2X3R-positive cells in ipsilateral DRGs of BCP rats. Ca2+ imaging analysis revealed that the EA stimulation decreased the percentage of α,β-meATP responsive neurons in DRGs and inhibited
calcium influx. Notably, the inhibitory effect of EA on
mechanical allodynia and nociceptive flinches was abolished by
intrathecal injection of α,β-meATP. These findings demonstrated EA stimulation ameliorated
mechanical allodynia and
thermal hyperalgesia in rat model of MRMT-1-induced BCP. EA exerts
analgesic effect on BCP by reducing the overexpression and functional activity of P2X3R in ipsilateral DRGs of BCP rats. Our work first demonstrates the critical and overall role of P2X3R in EA's
analgesia against peripheral sensitization of MRMT-1-induced BCP and further supports EA as a potential therapeutic option for
cancer pain in clinic.