Temporal therapy utilizing exosomes derived from M2 macrophages demonstrates enhanced efficacy in alleviating neuropathic pain in diabetic rats

Background: Diabetic pain patients have increased pain at night. Exosomes can relieve neuropathic pain. This studyaimed to investigate the efficacy of exosome administration at different time points in relieving diabetic neuropathicpain (DNP) in rats. Methods: M2 macrophages from bone marrow were induced in mice and exosomes were extracted. A diabeticrat model was induced using streptozotocin, with the mechanical withdrawal threshold (MWT) of the rats beingmeasured at ≤ 80% of the basal value after 14 days, indicating successful construction of the DNP rat model. Exosomes were administered on three consecutive days at ZT0 (zeitgeber time) and ZT12. Parameters includingblood glucose levels, body weight, MWT, and thermal withdrawal latency (TWL) were assessed in the rats. Thelumbar spinal cord of rats was examined on days 21 and 28 to measure inflammatory factors and observe theexpression of M1 and M2 microglia. Furthermore, microglia were exposed to lipopolysaccharide (LPS) and LPS +exosomes in a controlled in vitro setting to assess alterations in microglia phenotype involving the NF-kB p65 andIKBα inflammatory signaling pathways. Results: The findings revealed that administration of exosomes during the rat resting period at ZT12 resulted inincreased MWT and TWL, as well as a shift in microglia polarization towards the M2 phenotype. In vitro analysisindicated that exosomes influenced microglia polarization and suppressed the phosphorylation of NF-kB p65 andIKBα. Conclusions: Temporal therapy with exosomes effectively reduces pain in DNP rats by polarizing microglia andaffecting NF-kB p65 and IKBα signaling pathways.