Prenatal exposure to di-n-butyl phthalate induces anorectal malformations in male rat offspring

The objectives of this study were to investigate the dysplasia, histological malformations, and genetic abnormalities in male rats induced by maternal exposure to di-n-butyl phthalate (DBP). Here we report novel findings concerning developmental abnormalities resulting from prenatal exposure to DBP, which leads to significant anorectal malformations (ARMs) in male rat offspring. The incidence of ARMs was 39.5% in male offspring and all abnormal pups were complicated with secondary megacolon. General images, histological analysis and anatomy examination confirmed the malformation. The development abnormalities such as decreased bodyweight (BW) and anogenital distance (AGD), shortened body lengths (with tail removed), as well as increased abdominal circumference were observed at different developmental stages of ARMs in male rat. The developmental abnormalities in both solid organs (brain, heart, liver, spleen, lung and kidney) and reproductive organs (testes and epididymis) of abnormal pubs on PND35 were also investigated. In addition, the serum testosterone (T) level of ARMs in male rats on PND1 was significantly lower than that of controls with accompanying reduced expression of androgen receptor (AR), sonic hedgehog (Shh) and bone morphogenetic protein 4 (Bmp4) mRNA from tissues of the terminal rectum. These results conclusively demonstrate for the first time that in utero exposure to DBP leads to an increased likelihood for the development of ARMs and subsequent complicating megacolon in male rat offspring.