Di-n-butyl phthalate induced hypospadias relates to autophagy in genital tubercle via the PI3K/Akt/mTOR pathway.

OBJECTIVE: To explore the mechanisms of hypospadias induced by in utero exposure to din-butyl phthalate (DBP).

METHODS: Timed-pregnant Sprague-Dawley rats were administered 750 mg/kg of DBP by gavage from GD (gestation days) 13 to GD 18, whereas control group received corn oil. Genital tubercles (GTs) and blood samples were collected from male fetuses on GD 19. The serum testosterone concentration, apoptosis activity, autophagosomes and their related proteins (light chain 3 (LC3-I, LC3-II) ), and sequestosomes (SQSTM1/p62) in the GTs were then measured. Protein expression of protein kinase B (Akt), Beclin 1, phosphorylated Akt (p-Akt), p-S6, and phosphorylated mammalian target of rapamycin (p-mTOR) in the GTs were analyzed by Western blotting.

RESULTS: The incidence of hypospadias induced by DBP was 43.64% in male fetuses. The GT volume and GT volume/body weight of fetuses were significantly reduced in the hypospadias and the non-hypospadias groups. Apoptotic cell number was significantly decreased in the GTs of the hypospadias group, but unchanged in the non-hyposadias group. The ratio of LC3-II/LC3-I was higher in the GTs from DBP exposed fetuses compared to the control group. The ratio of LC3-II/LC3-I in the GTs was higher in the hypospadias group than in the non-hypospadias group. The number of autophagosomes was increased in the GTs of the hypospadias group. Protein expression of p-S6, p-mTOR, and p-Akt were significantly decreased in the GTs of hypospadiac rats.

CONCLUSIONS: DBP-induced hypospadias might be associated with apoptosis and autophagy mediated by the PI3K/Akt/mTOR signaling pathway in the GT.