Effect of Acupoint Injection of Magnetic Hydrogel on JAK1/STAT3 Expression in the Spinal Dorsal Horn of CCI Rats

This study aimed to prepare a thermosensitive magnetic hydrogel loaded with magnetic nanoparticles (Fe3O4) based on chitosan/β-glycerophosphate (CS/GP), and to evaluate its therapeutic effect on a chronic constriction injury (CCI) model of sciatic nerve pain in SD rats, exploring its feasibility as an alternative material for acupoint catgut embedding. The gelation properties and cytocompatibility of the Fe3O4-loaded chitosan/glycerophosphate (CS/GP/Fe3O4) hydrogel were observed through in vitro experiments. Mechanical paw withdrawal thresholds were measured before CCI modeling and on days 1, 3, 5, 7, and 14 postmodeling. The treatment group received injections of CS/GP/Fe3O4 hydrogel at the Zusanli (ST36) acupoint on the affected side, while the control group received catgut embedding at the same acupoint. Spinal cord tissue was collected on day 14 posttreatment, and the Western blot was used to detect the expression levels of janus kinase 1(JAK1) and signal transducer and activators of transcription 3 (STAT3) proteins in the spinal dorsal horn to investigate the analgesic mechanism. Thermosensitivity tests showed that the CS/GP/Fe3O4 hydrogel was liquid at room temperature (suitable for injection) and solidified into a gel at around 37 °C, demonstrating good thermosensitivity. Cytocompatibility tests indicated good biocompatibility of the hydrogel with fibroblasts. Behavioral tests showed that injection of the CS/GP/Fe3O4 hydrogel could increase the mechanical pain threshold in CCI rats. Western blot results showed that the CS/GP/Fe3O4 hydrogel could inhibit the expression of STAT3 and JAK1 in the spinal dorsal horn after CCI modeling, and the inhibitory effect was superior to that of the catgut embedding group. The CS/GP/Fe3O4 magnetic thermosensitive hydrogel exhibits good biocompatibility, injectability, and analgesic effects, showing promise as a novel alternative material for acupoint catgut embedding therapy in treating sciatic nerve pain.