Electroacupuncture on ST36 and GB39 Acupoints Inhibits Synovial Angiogenesis via Downregulating HIF-1α/VEGF Expression in a Rat Model of Adjuvant Arthritis

Abstract

Introduction. The hypoxia inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) play a key role in synovial angiogenesis in rheumatoid arthritis (RA). Therefore, this study aimed to test the hypothesis that electroacupuncture (EA) may inhibit RA synovial angiogenesis via HIF-1α/VEGF expression. Methods. Sprague-Dawley rats were randomly distributed to 4 groups: control, adjuvant arthritis (AA), AA+electroacupuncture (AA+EA), and AA+sham EA groups. AA model was induced by injection of Freund s complete adjuvant in bilateral hind footpad. 3 days after injection, EA was delivered to the acupoints Zusanli (ST 36) and Xuanzhong (GB 39) once every two days for a total of 8 times in the AA+EA group, while sham EA treatment was applied in the AA+sham EA group. The arthritis score, paw volume, and H&E staining for each animal were measured. CD34 expression in synovial tissue of ankle joint was observed by immunohistochemistry. HIF-1α and VEGF mRNA and protein levels in synovial tissue were determined by real-time quantitative PCR and Western blot, respectively. Results. Compared with rats in AA group, EA stimulation significantly decreased arthritis scores, paw volume, and pathological damage of synovial tissues. Moreover, EA markedly suppressed the synovial angiogenesis of AA rats, as evidenced by reduced CD34 positive expression. Furthermore, EA significantly reduced HIF-1α and VEGF mRNA and protein levels in synovial of AA rats. Finally, the CD34 expression in synovial tissue was positively correlated with HIF-1α and VEGF protein levels. Conclusion. EA on ST36 and GB39 acupoints can effectively inhibit synovial angiogenesis in the AA rat model via downregulating HIF-1α/VEGF expression.