Low-energy extracorporeal shock wave therapy is associated with reduced inflammation and fibrosis in an E2-induced rat model of endometriosis and remains effective under menopause-mimicking conditions.

Abstract

Background: Endometriosis is an estrogen-dependent inflammatory disorder marked by ectopic lesions, chronic pelvic inflammation, and frequent recurrence. Extracorporeal shock wave therapy (ESWT) is a non-invasive modality with anti-inflammatory and regenerative potential, but its efficacy under varying estrogen conditions remains unclear.

Methods: Endometriosis-like lesions were induced in female rats by suturing uterine fragments to the peritoneum, followed by daily 17β-estradiol (E₂) or PBS for 28 days. Sprague-Dawley rats were assigned to control, E₂, E₂ + ESWT (0.1 or 0.25 mJ/mm²), or ovariectomy (OVX) + ESWT groups. ESWT was applied twice weekly for three weeks. Body weight, food intake, lesion morphology, histology, and serum E₂ were assessed. Inflammatory and fibrotic markers were analyzed as follows: transforming growth factor beta (TGF-β) and tumor necrosis factor-alpha (TNF-α) were evaluated by both immunohistochemistry (IHC) and quantitative real-time RT-PCR (qRT-PCR), whereas interleukin (IL)-6, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), cyclooxygenase (COX)-2, vascular endothelial growth factor (VEGF), cytokeratin (CK)-18, superoxide dismutase (SOD), inducible nitric oxide synthase (iNOS), and hypoxia-inducible factor-1 alpha (HIF-1α) were assessed by qRT-PCR only.

Results: E₂ reduced body weight and food intake and induced cystic peritoneal lesions with upregulated fibrotic and inflammatory markers. ESWT at both energy levels significantly reduced lesion size, cystic formation, the number of endometrial glands (hematoxylin-eosin, H&E staining), fibrosis area ratio (Masson trichrome staining), and expression of fibrosis-, inflammation- oxidative stress-, and hypoxia-related genes and proteins regardless of ovarian status. OVX combined with ESWT produced comparable or slightly enhanced reductions in several markers. ESWT did not alter systemic E₂ levels, whereas OVX resulted in reduced serum estrogen levels.

Conclusion: Low-energy ESWT attenuated E₂-induced endometriotic lesions, accompanied by reductions in proliferation, inflammation, and fibrosis, without altering circulating estrogen levels. These effects were also observed under menopause-mimicking conditions with controlled estrogen exposure. These findings suggest that ESWT may serve as a complementary non-hormonal adjunctive approach and may provide a useful experimental framework for future mechanistic and preclinical studies.