Seminal Vesicle Abnormalities and Exploratory miR-664-5p and FOXO Findings in Aged Mice Following Long-Term Butyl Benzyl Phthalate Exposure

Butyl benzyl phthalate (BBP), a widely used endocrine-disrupting chemical, has been associated with reproductive toxicity; however, its long-term effects during aging remain poorly understood. In the present study, we examined the effects of prolonged BBP exposure on the male reproductive system using naturally aged C57BL/6J mice. Mice received BBP at 169 μg/kg/day in drinking water for 10 or 22 months and were analyzed at 24 months of age. No significant differences in body weight, food intake, or water consumption were observed among the experimental groups. Representative gross images showed apparent distension and dark-red discoloration of the seminal vesicles in BBP-exposed aged mice. Compared with Young mice, the BBP-exposed aged groups showed higher expression of IL-1β, IL-6, TNFα, SOD1, and SOD2 and lower CAT expression in the seminal vesicle. H2DCFDA fluorescence showed a non-significant increasing trend. Because an untreated age-matched Old group was not included in the seminal vesicle analyses, the effects of aging and BBP could not be distinguished. In contrast, the testis showed limited changes in inflammatory cytokine-, antioxidant enzyme-, and steroidogenesis-related gene expression and in H2DCFDA fluorescence relative to the untreated Old group. Exploratory miRNA sequencing of pooled testicular RNA and comparison with a TM3 Leydig cell dataset identified miR-664-5p as a candidate showing higher relative abundance in both datasets. TargetScan analysis predicted binding sites for miR-664-5p in FOXO1 and FOXO3. In BBP-treated TM3 cells, FOXO3 protein expression was decreased, and FOXO6 expression was increased, whereas FOXO1 showed no consistent dose-dependent change. These molecular findings do not establish direct regulation of FOXO proteins by miR-664-5p or explain the seminal vesicle findings.