Maternal exposure to di-n-butyl phthalate (DBP) induces combined anorectal and urogenital malformations in male rat offspring

Anorectal malformations in combination with hypospadias (ARMs & hypospadias) are a type of complex congenital malformations. The underlying mechanisms of this deformity are largely unknown. In this study, we comprehensively characterized the dysplasia, histological malformations, and genetic changes of ARMs & hypospadias in male rats after maternal exposure to di-n-butyl phthalate (DBP) by gastric intubation at doses of 850 mg/kg bw/day during GD11-15. On postnatal day 1, anatomical and histopathological analysis confirmed combined malformations of the genital tubercle (GT), terminal rectum (TR) and testes. DBP-induced dysplasia was also seen in the kidney, lung, spleen, heart and liver of ARMs & hypospadias male rats. Moreover, decreased levels of serum testosterone, as well as reduced expression of genes related to the androgen signaling pathway (Cyp11a1, Hsd3b, Scarb1, Star, AR, Srd5a2) were found in the testes of ARMs & hypospadias male rats after DBP exposure as compared to untreated controls. Further, decreased mRNA levels of Shh, Fgf10, Gli2, Gli3, Bmp4, Wnt5a, Hoxa13, Hoxd13, Fgfr2 and AR were observed in TR and GT in the ARMs & hypospadias group. These results provide evidence that prenatal exposure to DBP can lead to combined anorectal and urogenital malformations as well as dysplasia of the testes.