[Effect of electroacupuncture on the A20/NF-κB/NLRP3/GSDMD signaling pathway in rats with primary dysmenorrhea]

To observe the effect of electroacupuncture (EA) at "Guanyuan" (CV4) and "Sanyinjiao" (SP6) on the ubiquitin-editing enzyme A20 (A20)/nuclear factor-κB (NF-κB)/NOD-like receptor protein 3 (NLRP3)/Gasdermin D (GSDMD) signaling pathway in rats with primary dysmenorrhea (PDM).

Female naive SD rats were randomly divided into blank, model, EA and medication groups (n=6 per group). PDM rat model was established by subcutaneous injection of estradiol benzoate combined with intraperitoneal injection of oxytocin. EA (50 Hz) was applied to CV4 and bilateral SP6 of rats in the EA group, with needles retained for 20 min, once daily for 10 consecutive days. Rats in the medication group received ibuprofen(125 mg/100 mL, 0.8 mL) by gavage for 10 consecutive days. At the 11^th day, writhing behavior of rats was assessed. Uterine pathology was assessed by HE staining. Serum contents of prostaglandin F2α (PGF2α) and tumor necrosis factor-α (TNF-α) were measured by ELISA. Protein expression of A20, phosphorylated NF-κB p65 (p-NF-κB p65), NF-κB p65, NLRP3, Caspase-1, Interleukin (IL)-1β, GSDMD, and GSDMD N-terminal domain (GSDMD-N) in uterine tissue were detected by Western blot.

Compared with the blank group, the writhing times, scores, and latency period, the contents of PGF2α and TNF-α in serum, and the protein expression levels of p-NF-κB p65, NF-κB p65, NLRP3, Caspase-1, IL-1β, GSDMD, and GSDMD-N in the uterine tissues of rats in the model group were all significantly increased (P<0.05, P<0.01). In contrast, the expression level of A20 was decreased (P<0.01). Compared with the model group, the writhing times and scores, the contents of PGF2α and TNF-α in serum, and the protein expression levels of p-NF-κB p65, NF-κB p65, NLRP3, GSDMD, and GSDMD-N in rats of the EA and medication groups were all significantly decreased (P<0.05, P<0.01). Conversely, the writhing latency period and the expression level of A20 were significantly increased (P<0.01). After modeling, the endometrial epithelial cells were dead, accompanied by endometrial edema and neutrophil infiltration, which was milder in the EA and the medication groups.

EA intervention can effectively relieve inflammatory response in PDM rats, which may be associated with its effect in activating the A20-mediated NF-κB negative feedback pathway and inhibiting the NF-κB/NLRP3/GSDMD signaling pathway.