Mild Moxibustion Alleviates Primary Dysmenorrhea in Rats Through TRPV1-Associated Modulation of NF-κB Signaling and Uterine Oxidative Stress

Kuo Bi,1,2,* Xiran Xiao,1,2,* Bingna Hou,1,2 Ruixue Lu,1 Ruijuan Zhang,1,2 Yan Zhang,1,2 Di Wang,1,2 Xinhua Li,1,2 Zhiguo Zhao,1 Liyun Yang1,21College of Acupuncture-Moxibustion and Tuina, Hebei University of Chinese Medicine, Shijiazhuang, Hebei, People’s Republic of China; 2Hebei International Joint Research Center for Dominant Diseases in Chinese Medicine and Acupuncture, Hebei University of Chinese Medicine, Shijiazhuang, Hebei, People’s Republic of China*These authors contributed equally to this workCorrespondence: Zhiguo Zhao, College of Acupuncture-Moxibustion and Tuina, Hebei University of Chinese Medicine, No. 3 Xingyuan Road, Shijiazhuang, Hebei, 050200, People’s Republic of China, Email [email protected] Liyun Yang, College of Acupuncture-Moxibustion and Tuina, Hebei University of Chinese Medicine, No. 3 Xingyuan Road, Shijiazhuang, Hebei, 050200, People’s Republic of China, Email [email protected]: To investigate the therapeutic effect and analgesic mechanism of mild moxibustion at Shenque (CV8) and Guanyuan (CV4) in a primary dysmenorrhea (PD) rat model, focusing on the involvement of TRPV1-NF-κB signaling and uterine oxidative stress.Methods: Forty female Sprague-Dawley (SD) rats were randomly divided into five groups (n=8): blank group (BG), model group (MG), mild moxibustion group (MMG), antagonist capsazepine group (CPZG), and ibuprofen group (IG). PD models were established through cold stimulation combined with estradiol benzoate and oxytocin injection. The MMG received mild moxibustion at "Shenque” (CV8) and "Guanyuan” (CV4) acupoints. The CPZG was pretreated with capsazepine (CPZ) before moxibustion. The IG received ibuprofen via gavage. After intervention, pain thresholds and writhing scores were measured; uterine pathology was observed via HE staining; ELISA, colorimetric assay, immunohistochemistry (IHC), and Western blotting were used to detect relevant biomarkers.Results: Mild moxibustion significantly elevated pain thresholds and reduced writhing scores (vs MG, P< 0.01). Capsazepine partially reversed these analgesic effects (vs MMG, P< 0.01). Mild moxibustion decreased serum IL-1β, TNF-α, and PGF2α while increasing PGE2 (vs MG, P< 0.01). Mild moxibustion upregulated TRPV1 expression at acupoints (vs MG, P< 0.01), whereas capsazepine suppressed TRPV1 expression (vs MMG, P< 0.01). Mild moxibustion downregulated uterine NF-κB P-p65 and COX-2 expression (vs MG, P< 0.01), while CPZG upregulated these proteins (vs MMG, P< 0.01). Furthermore, mild moxibustion upregulated uterine SOD2 expression (vs MG, P< 0.05), decreased MDA content, and increased GSH content and SOD activity (vs MG, P< 0.05 or P< 0.01).Conclusion: Mild moxibustion at CV8 and CV4 alleviates PD in rats through mechanisms involving TRPV1 activation, NF-κB pathway modulation, and improvement of uterine oxidative stress. These findings provide a preclinical basis for further investigation.Keywords: primary dysmenorrhea, mild moxibustion, TRPV1, NF-κB, oxidative stress