Comparison of the establishment of rat intrauterine adhesion models utilizing the double-injury method at different periods

CONTEXT: A suitable animal model of intrauterine adhesion (IUA) is crucial for further investigating its pathological mechanisms and exploring effective therapeutic strategies. AIMS: This study compared the efficacy of establishing IUA animal models in non-pregnant rats at stages of estrous cycles versus pregnant rats using the dual-injury method, aiming to identify a model that better reflects the clinical pathogenesis of IUA. METHODS: Sprague Dawley female rats were randomly divided into control group (estrous phase, non-estrous phase) and model group (estrous phase, non-estrous phase and pregnancy phase). A dual-injury method was used to establish the IUA model. Fourteen days after modeling, the rat uterus was collected to assess the modeling effect by analyzing the number of endometrial glands and the degree of fibrosis and by detecting the expression levels of transforming growth factor-beta 1 (TGF-β1), interleukin 6 (IL-6), and integrin ανβ3 proteins. KEY RESULTS: Histological and molecular analyses were performed on the uterine tissues of each group. The results demonstrated that the dual-injury method effectively establishes an IUA animal model. The pregnancy model group had fewer glands and a larger area of fibrosis compared to the estrous and non-estrous model groups (P < 0.05). The pregnancy model group had higher expression levels of TGF-β1, IL-6 proteins and a lower expression level of integrin ανβ3 protein than did the estrous and non-estrous model groups (P < 0.05). CONCLUSION: Modeling during pregnancy yielded superior outcomes compared with modeling at stages of estrous cycles in non-pregnant rats. IMPLICATIONS: These findings have provided valuable insights for future researchers in selecting appropriate animal models to further elucidate the pathogenesis of clinical IUA.