Mechanism of electroacupuncture in treating uterine endometrial fibrosis in intrauterine adhesions rats based on Wnt/β-catenin pathway-mediated epithelial-mesenchymal transition.

Objectives: To observe the effect of electroacupuncture (EA) on the Wnt/β-catenin signaling pathway and epithelial-mesenchymal transition (EMT)-related proteins in rats with intrauterine adhesions (IUA), so as to explore the possible mechanisms of EA in repairing endometrial damage in IUA.

Methods: Female SD rats were randomly divided into blank, model, EA, and ICG-001 groups, with 10 rats in each group. The IUA model was established by using mechanical scraping combined with lipopolysaccharide infection for double injury. In the EA group, "Guanyuan" (CV4) was needled and EA (2 Hz/15 Hz, 1-2 mA) was applied to "Zusanli" (ST36) and "Sanyinjiao"(SP6) on both sides. In the ICG-001 group, ICG-001 (5 mg/kg), the inhibitor of β-catenin was intraperitoneally injected. After intervention, samples were taken from 5 rats in each group, and uterine endometrium morphology, endometrial thickness, and gland counts were observed using HE staining. Masson staining was used to assess the degree of fibrosis in the endometrial tissue. Immunohistochemistry was used to detect the positive expression of transforming growth factor β1 (TGF-β1), α-smooth muscle actin (α-SMA), fibronectin (FN), connective tissue growth factor (CTGF), type I collagen (Col- Ⅰ), glycogen synthase kinase-3β (GSK-3β), β-catenin, E-cadherin, N-cadherin, and Vimentin in the endometrial tissue. Western blot was used to detect the relative expression of GSK-3β, β-catenin, E-cadherin, N-cadherin, and Vimentin proteins in the endometrial tissue. Another 5 rats from each group were placed in cages with male rats after intervention to record the number of embryo implantations.

Results: Necrosis and loss of endometrial tissue in the model group observed after HE staining were alleviated in the EA group, better than those in the ICG-001 group. Compared with the blank group, the numbers of glands and endometrial thickness in the uterine endometrial tissue, relative expression and positive expression of E-cadherin and GSK-3β proteins in the uterine endometrial tissue, and embryo implantation numbers were reduced(<0.000 1, <0.001, <0.01) in the model group, while fibrosis area ratio in the uterine endometrial tissue, TGF- β 1, α -SMA, FN, CTGF, Col- Ⅰ positive expressions, N-cadherin, Vimentin, and β-catenin proteins expression and positive expression were increased(<0.000 1, <0.001, <0.01). Compared with the model group, the number of glands and endometrial thickness, E-cadherin and GSK-3β proteins expression and positive expression, and embryo implantation numbers were increased (<0.001, <0.05, <0.01) in the EA and ICG-001 groups, while the fibrosis area ratio in the uterine endometrial tissue, TGF-β1, α-SMA, FN, CTGF, Col- Ⅰ positive expression, and N-cadherin, Vimentin, and β-catenin proteins expression and positive expression were decreased(<0.001, <0.01, <0.05). Compared with the EA group, the differences of the above-mentioned indicators in the ICG-001 group were not statistically significant.

Conclusions: EA may reverse the EMT process and reduce the degree of fibrosis in endometrial tissue by inhibiting the Wnt/β-catenin signaling pathway, thereby promoting the repair of endometrial damage in IUA.