The Analgesic Effects and Anti-Inflammatory Mechanisms of Acupuncture at Zusanli (ST36) in Animal Models of Rheumatoid Arthritis: Systematic Review and Meta-Analysis.

PURPOSE: This study aimed to systematically evaluate the analgesic and anti-inflammatory effects of isolated acupuncture at Zusanli (ST36) in animal models of rheumatoid arthritis (RA), providing evidence-based insights for clinical translation and mechanism research. METHODS: PubMed, Web of Science, and Embase were searched from inception to December 2025 for controlled trials of standalone ST36 acupuncture in RA animals. Two reviewers independently screened studies, extracted data, assessed risk of bias, and meta-analyses were performed via RevMan 5.4 and Stata 18.0. RESULTS: Twenty-four studies were included. ST36 acupuncture significantly elevated paw withdrawal latency(PWL), tail flick latency(TFL), ear thermal pain threshold, paw withdrawal threshold (PWT) and knee joint pressure pain threshold (all P<0.0001), increased mast cell degranulation rate (MD=35.06, 95% CI 8.46-61.67, P=0.010), reduced knee joint circumference (MD=-1.62, 95% CI -2.16--1.09) and paw swelling degree (MD=-0.09, 95% CI -0.14--0.04), upregulated knee joint surface temperature (MD=0.12, 95% CI 0.08-0.17), and downregulated tumor necrosis factor-alpha (TNF-α) (SMD=-2.25),interleukin-1 beta (IL-1β) (SMD=-2.12) and interleukin-6 (IL-6) (SMD=-1.97) (all P<0.00001). No significant difference was found in synovial tissue histopathological score (P=0.16). High heterogeneity existed in partial outcomes; sensitivity analysis confirmed most results were robust except paw swelling degree, and publication bias was detected (P<0.05). CONCLUSION: Isolated acupuncture at ST36 exerts significant analgesic and anti-inflammatory effects in RA animal models, potentially mediated by regulating inflammatory cytokines and immune cells. However, methodological quality limitations and publication bias restrict the findings, requiring validation by high-quality future studies.