Abstract
Background:
Menopause-induced estrogen deficiency triggers inflammatory responses and promotes apoptosis in urogenital tissues, contributing to genitourinary syndrome of menopause. Soybean extract contains phytoestrogenic isoflavones.

Aim:
To investigate the effects of soybean extract against menopause-induced inflammation and apoptosis in ovariectomized rats.

Methods:
Forty female Rattus norvegicus, Wistar strain were randomly allocated into five experimental groups (n = 8 per group): a normal control group (KN), an ovariectomized negative control group (KNeg), an ovariectomized positive control group receiving estrogen therapy (0.009 mg/day; KPos), and two ovariectomized treatment groups administered soybean extract at doses of 300 mg/mL/day (P1) and 600 mg/mL/day (P2) for 40 days following ovariectomy. Serum CRP concentrations were quantified using enzyme-linked immunosorbent assay (ELISA), whereas E-selectin and caspase-3 expression in vaginal and urethral tissues were assessed by immunohistochemistry (IHC).

Results:
Soybean extract treatment induced lower E-selectin expression in both vaginal and urethral tissues (p < 0.05), with the highest dose (600 mg/mL/day) having the most pronounced effect. IHC analysis demonstrated that E-selectin expression was markedly lower in the P2 group (29.17 ± 16.86% in vaginal tissue and 13.33 ± 11.69% in urethral tissue) than in the negative control group (KNeg: 60.00 ± 14.14% in vaginal tissue and 35.00 ± 5.48% in urethral tissue). Similarly, caspase-3 expression was lower in the treatment groups (P2: 25.00 ± 10.95% vaginal, 18.33 ± 7.53% urethral) than in the negative control (KNeg: 33.33 ± 15.06% vaginal, 20.83 ± 9.17% urethral), although the difference was statistically significant. Serum CRP levels were also lower in the soybean extract groups (P2: 2.02 ± 0.43 ng/mL) than in the negative control (KNeg: 2.78 ± 0.80 ng/mL), but the difference was not statistically significant.

Conclusion:
Glycine max L. Merrill extract significantly decreased the expression of E-selectin in ovariectomized rats, showing a potential protective role. The effects on caspase-3 and CRP were observed as a reducing trend; however, they were not statistically significant in all comparisons.

Key words: CRP; Caspase-3; E-selectin; Soybean extract; Urogenital atrophy.