Effect of moxibustion on N-methyl-D-aspartate receptor subtype 2B expression in hippocampus of rheumatoid arthritis model rats / 针灸推拿医学（英文版）

ABSTRACT

Objective: To observe the effect of moxibustion on the expression of N-methyl-D-aspartic acid (NMDA) receptor subtype 2B (NR2B) in the hippocampus of rheumatoid arthritis (RA) rats, and to explore the analgesic mechanisms of moxibustion in RA treatment. Methods: Sixty male Sprague-Dawley rats were randomly divided into a normal group, a model group, a moxibustion group, a moxibustion + NMDA receptor antagonist (AP-5) group, and a moxibustion + NMDA receptor agonist (NMDA) group, with 12 rats in each group. Except for the normal group, rats in the other four groups were treated with complete Freund's adjuvant in a windy, cold, and damp environment to replicate RA models. Rats in the moxibustion group received suspended moxibustion with moxa sticks at Shenshu (BL23) and Zusanli (ST36), and the two points were used alternately. After intraperitoneal injection of AP-5 or NMDA, rats in the moxibustion + AP-5 group and the moxibustion + NMDA group received the same moxibustion intervention as in the moxibustion group, once a day for 15 d. The thermal withdrawal latency (TWL) of rats in each group was detected before and after modeling and after the 15-day intervention. After the 15-day intervention, hematoxylin-eosin staining was performed to observe the pathological changes in knee joints. The real-time fluorescence quantitative polymerase chain reaction method was used to detect the mRNA expression of NR2B in the hippocampus; Western blotting assay was used to detect the protein and the phosphorylated protein expression of hippocampal NR2B. Results: The synovial tissue was proliferated, the synovial lining was significantly thickened, the pannus was formed, and the cartilage and bone tissues were significantly damaged in the model group. After intervention, the pathological morphology of the knee joints in the moxibustion group, the moxibustion + AP-5 group, and the moxibustion + NMDA group was significantly improved, and the improvement in the moxibustion + AP-5 group was more notable than that in the moxibustion + NMDA group. Compared with the normal group, the TWL was significantly decreased (P<0.01), and the mRNA, protein, and phosphorylated protein expression levels of hippocampal NR2B were significantly increased in the model group (P<0.01). Compared with the model group, the TWL of each intervention group was significantly increased (P<0.01 or P<0.05), and the mRNA, protein, and phosphorylated protein expression levels of hippocampal NR2B were significantly decreased (P<0.01). Compared with the moxibustion group, the TWL was significantly increased (P<0.01), and the mRNA, protein, and phosphorylated protein expression levels of hippocampal NR2B were significantly decreased in the moxibustion + AP-5 group (P<0.01); the TWL was significantly decreased (P<0.01), and the mRNA, protein, and phosphorylated protein expression levels of hippocampal NR2B were significantly increased in the moxibustion + NMDA group (P<0.01). Conclusion: Moxibustion reduces hyperalgesia in RA inflammatory rats. The analgesic effect may be related to the decrease in the expression and phosphorylation levels of NR2B in the hippocampus.