Direct moxibustion exerts an analgesic effect on cervical spondylotic radiculopathy by increasing autophagy via the Act A/Smads signaling pathway

Background: Direct moxibustion (DM) is reported to be useful for cervical spondylotic radiculopathy (CSR), but the analgesic mechanism remains unknown. Autophagy plays a protective role in neuronal Apoptosis, Act A/Smads signaling pathway has been confirmed to be associated with the activation of Autophagy. The study aimed to explore the effect of DM on Autophagy in rats with CSR and the involvement of Act A/Smads signaling pathway.

Methods: Rats were randomly divided into Sham, CSR, CSR + DM, CSR + DM + 3-MA (PI3K Inhibitor), and CSR + DM + SB (Act A inhibitor) group. Three days after establishment of CSR model with a fish line inserted under the axilla of the nerve roots, DM at Dazhui (GV14) was performed six times once for seven consecutive days. Western blot and immunofluorescence staining were used to observe the expression of the neuronal Autophagy molecule LC3II/I, Atg7, and Act A/Smads signaling molecule Act A, p-Smad2, and p-Smad3. Bcl-2/Bax mRNA expression was measured by real time PCR.

Results: DM improved the pain threshold and motor function of CSR rats and promoted the expression of Act A, p-Smad2, p-Smad3, LC3II/I, and Atg7 in the entrapped-nerve root spinal dorsal horn. DM reduced the expression of Bax mRNA and decreased the number of apoptotic neurons. 3-MA and Act A inhibitor SB suppressed the expression of above-mentioned proteins and reduced the protective effect of DM on apoptotic neurons.

Conclusion: DM exerts analgesic effects by regulating the Autophagy to reduce cell Apoptosis and repair nerve injury, and this feature may be related to the Act A/Smads signaling pathway.