OBJECTIVETo detect the differential expression of Notch1 in the genital tubercle (GT) of fetal male rats with hypospadias induced by maternal exposure to Di-n-butyl phthalate (DBP) and that in normal control fetal rats in order to further explore the role of Notch1 in DBP-induced hypospadias.

METHODSTwenty pregnant SD rats were equally and randomly divided into an experimental and a control group, the former given DBP and the latter soybean oil intragastrically at 800 mg/(kg x d) and 2 ml/d respectively from gestation day (GD) 14 to GD 18. On GD 19, the birth weight (BW), anogenital distance (AGD) and hypospadias incidence were recorded, GTs of the fetal male rats collected, and the expression of Notch1 analyzed by Western blot and immunohistochemistry.

RESULTSThe BW of the fetal male rats was (4.40 +/- 0.30) g in the experimental group, significantly lower than (6.11 +/- 0.40) g in the control (P <0.05), and the AGD was (2.17 +/- 0.18) mm in the former, markedly shorter than (3.28 +/- 0.16) mm in the latter (P<0.05). The incidence of hypospadias was 42.9%. The relative expression of Notch1 was remarkably lower in the hypospadiac rats than in the normal controls (0.671 +/- 0.021 vs 1.327 +/- 0.031, P<0.05), and it was mainly located in the epithelial cells of the GT. The staining intensity was obviously weaker in the hypospadias than in the normal control group.

CONCLUSIONDBP has an obvious toxic effect on fetal male rats and can change the expression of Notch1 in the GT. It possibly affects cell proliferation and apoptosis and epithelial-to-mesenchymal transition (EMT), resulting in the occurrence of hypospadias.