[The effect of diethylstilbestrol on inducing abdominal cryptorchidism and relevant genetic expression in rats]

To study the effect of diethylstilbestrol (DES) at different doses on transabdominal testicular descent in rats and the expression of INSL3 in the testis and HOXA10 in the gubernaculum.

Fifty E13.5 (embryonic day 13.5) pregnant female SD rats were randomly divided into five groups that received a subcutaneous injection of DMSO, 2.5, 5.0, 10.0 and 20.0 mg/kg DES (group A, B, C, D and E), respectively. Male offspring were killed at E19.5, and then fetal mortality, the degree of transabdominal testicular ascent (DTA) was determined by a stereomicroscope. The mRNA expressions of INSL3 in the testis and HOXA10 in the gubernaculum were determined by RT-PCR. The expression of INSL3 protein was determined by Western blotting.

Male fetal mortality in group A, B, C, D, and E were 3.57%, 6.90%, 12.00%, 19.23% and 36.36%, respectively, which showed a dose-effect relationship between DES and the male fatal mortality (r=0.999, P<0.01). DTA in group B, C, D and E were (23.7+/-1.7) U, (38.8+/-1.9) U, (49.3+/-1.8) U and (58.6+/-2.1) U that were significantly larger than that in group A [(8.5+/-1.3) U] (q=46.12, 88.53, 120.44 and 141.37, respectively, P<0.01). There was also a dose-effect relationship between DES and DTA. In group B, C, D, and E, the expression of INSL3 mRNA were 0.9570+/-0.1490, 0.6760+/-0.1380, 0.0170+/-0.0040 and 0.0013+/-0.0003, respectively; the expressions of INSL3 protein were 0.8360+/-0.1520, 0.5310+/-0.1070, 0.0140+/-0.0020 and 0.0011+/-0.0003, respectively, which were significantly larger than the expression of INSL3 mRNA (1.801+/-0.126) and INSL3 protein (1.612+/-0.134) in group A (qmRNA=40.4840, 52.4402, 83.1585 and 82.0582, respectively, and qprotein=38.6151, 52.2747, 77.2756 and 76.1983, respectively, P<0.01). The expression of HOXA10 mRNA in group A, B, C, D, and E were 0.945+/-0.125, 0.940+/-0.119, 0.656+/-0.115, 0.544+/-0.118 and 0.463+/-0.114, respectively. Compared with the expression of HOXA10 mRNA in group A, the expression of group B was not significantly different (q=0.2213, P>0.05), those in other groups were down-regulated significantly (q=12.4304, 17.2477 and 20.2789, respectively, P<0.01).

DES inhibited transabdominal testicular descent dose-dependently via down-regulating the expression of INSL3. HOXA10 may play no role in low-dosage DES induced intra-abdominal cryptorchidism, but down-regulated HOXA10 mRNA was involved in high-dosage DES induced ones.