Electroacupuncture alleviates pain in rats with Cervical Spondylotic Radiculopathy by promoting M2 polarization of spinal macrophages through suppression of Piezo1 protein expression.

Abstract

BACKGROUND: Macrophage polarization regulates CSR pain. Piezo1, a mechanosensitive channel, modulates this process. Acupuncture promotes M2 polarization, and our team found electroacupuncture (EA) alleviates CSR pain. However, whether EA acts via Piezo1 remains unclear. METHODS: CSR was induced in rats by inserting a nylon filament into the cervical spinal canal to compress the nerve roots. On day 6 post-surgery, gait scoring and thermal pain threshold tests confirmed successful modeling. Rats were assigned to Sham, CSR, EA, and EA+Yoda1 groups. From day 7, the EA and EA+Yoda1 groups received 20 min of EA at bilateral LI4 and LR3 daily for 7 days. The EA+Yoda1 group was injected intraperitoneally with Yoda1 (1.5 mg/kg) before each session; the EA group received vehicle. After treatment, behavioral tests were repeated, and spinal cords were collected. Histopathology was assessed by Hematoxylin and eosin (H&E) staining. Piezo1 and polarization-related markers were detected by immunofluorescence, Western blot(WB), and ELISA. RESULTS: EA improved motor behavior and thermal pain thresholds in CSR rats. It suppressed the expression of Piezo1 in the spinal cord, as well as the levels of CD86, iNOS, IL-6, NF-κB, and p-NF-κB, while promoting the expression of CD206, Arg1, TGF-β, and IL-10. These effects were reversed by treatment with Yoda1, suggesting that electroacupuncture alleviates neuropathic pain in CSR rats by downregulating Piezo1 expression and promoting macrophage polarization toward the M2 phenotype.