BACKGROUNDPrenatal exposure to diaethylstilbestrol (DES) has been found to lead to intra-abdominal cryptorchidism, but the mechanism is still not completely clear. This study investigated the roles of the INSL3/LGR8 system and HOXA10 in DES-induced intra-abdominal cryptorchidism (DIIAC). The effect of DES on steroidogenic factor-1 (SF-1), that has been reported to control transcription of insulin-like factor 3 (INSL3), was also investigated.

METHODSFifty pregnant female SD rats at embryonic day 13.5 (E13.5) were randomly assigned to five groups that received a subcutaneous injections of dimethyl sulfoxide (control), 2.5 mg/kg, 5 mg/kg, 10 mg/kg, or 20 mg/kg of DES. Male offspring were sacrificed at E19.5, and fetal mortality and the degree of transabdominal testicular ascent (DTA) were determined under a stereomicroscope. The mRNA expression of INSL3 and SF-1 in the testis and leucine rich repeat-containing G protein-coupled receptors 8 (LGR8) and homeobox-A10 (HOXA10) in the gubernaculum were determined by RT-PCR. The expression of INSL3 protein was determined by Western blotting.

RESULTSHigher fetal mortality and DTA were induced by DES in a dose-dependent manner (P < 0.01). Compared with the control group, the expression of INSL3 and SF-1 mRNA were down-regulated in a dose-dependent manner (P < 0.01), as was INSL3 protein; HOXA10 in the 2.5 mg/kg group and LGR8 mRNA in the 2.5 mg/kg and 5 mg/kg groups were not significantly different (P > 0.05); HOXA10 mRNA in groups C, D, and E decreased significantly and LGR8 mRNA levels in groups D and E increased significantly (P < 0.05, P < 0.01, respectively).

CONCLUSIONSDES can inhibit transabdominal testicular descent in a dose-dependent manner via down-regulating the expression of INSL3, which is induced by down-regulating the expression of SF-1. HOXA10 may not be involved in DES induced intra-abdominal cryptorchidism at 2.5 mg/kg, but is involved at 5, 10 and 20 mg/kg. LGR8 may not be responsible for DES-induced transabdominal testicular maldescent.