ObjectiveTo construct intrauterine adhesion (IUA) mouse models induced by two different concentrations of ethanol injury, compare the phenotypes, and optimize a more stable IUA modeling method.MethodsTwenty 8-week-old female C57BL/6N mice were randomly divided into two groups: the 95% ethanol injury group and the 50% ethanol injury group. Using a self-control method, the left uterine horn was infused with ethanol to establish the IUA model, while the right uterine horn was infused with saline as the sham operation. Five mice from each group were euthanized on day 7 and 15 after modeling, and uterine tissues were collected. Hematoxylin-eosin (HE) staining was used to observe the endometrial pathology, and Masson staining was used to assess the degree of endometrial fibrosis. Quantitative real-time PCR was employed to detect the expression levels of fibrosis markers and pro-inflammatory factors in the uterine tissues.ResultsCompared to the sham operation, these two ethanol injury led to a significant reduction in elasticity of the uterus, an increase in inflammatory infiltration, and a marked increase in the degree of fibrosis on day 7 after modeling (P<0.05). The 95% ethanol injury group showed a significant decrease in endometrial thickness (P<0.05), whereas no significant change was observed in the 50% ethanol injury group when compared to the sham operation (P>0.05). The expression levels of fibrotic marker molecules collagen type Ⅳ alpha 1 chain (Col4A1), α-smooth muscle actin (α-SMA), transforming growth factor-β (TGF-β), and pro-inflammatory factors tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were significantly elevated in the 50% ethanol injury group when compared to the sham operation (P<0.05), although there was an increasing trend of the same markers in the 95% ethanol injury group, the differences were not statistically significant (P>0.05). On day 15 after modeling, the histopathological changes in both ethanol injury groups were not significant when compared to the sham operation, the expression levels of Col4A1, TGF-β, TNF-α and IL-1β remained significantly higher in the 50% ethanol injury group (P<0.05), while only IL-1β was significantly elevated in the 95% ethanol injury group (P<0.05).ConclusionUterine infusion with 95% ethanol results in more marked histopathological changes in the IUA mouse model compared to the 50% ethanol injury group. The 95% ethanol injury model is suitable for histopathological studies. However, the 50% ethanol injury group shows higher expression levels of fibrosis markers and pro-inflammatory factors compared to the 95% ethanol injury group, suggesting that the 50% ethanol injury model is more suitable for molecular pathological study.