Effect of electroacupuncture at ST36 on the cerebral metabolic kinetics of rheumatoid arthritis rats

Electroacupuncture (EA) has been shown to enhance the recovery of symptoms in rheumatoid arthritis (RA); however, the underlying mechanism remains unclear. Both the pathogenesis of RA and the therapeutic effects of EA are closely associated with the metabolic activity of the brain. In this study, we investigated the effect of EA at the “Zusanli” acupoint (ST36) on a rat model of collagen-induced rheumatoid arthritis (CIA). The results demonstrated that EA effectively alleviated joint swelling, synovial hyperplasia, cartilage erosion, and bone destruction in CIA rats. Additionally, the metabolic kinetics study revealed a significant increase in the ¹³C enrichment of GABA₂ and Glu₄ in the midbrain of CIA rats treated with EA. Correlation network analysis showed that changes in Gln₄ levels in the hippocampus were strongly associated with the severity of rheumatoid arthritis. Immunofluorescence staining of c-Fos in the midbrain’s periaqueductal gray matter (PAG) and hippocampus demonstrated increased c-Fos expression in these regions following EA treatment. These findings suggest that GABAergic and glutamatergic neurons in the midbrain, along with astrocytes in the hippocampus, may play vital roles in the beneficial effects of EA on RA. Furthermore, the PAG and hippocampus brain regions hold potential as critical targets for future RA treatments. Overall, this study provides valuable insights into the specific mechanism of EA in treating RA by elucidating the perspective of cerebral metabolism.