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

OBJECTIVE: 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.

METHOD: 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.

RESULTS: 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).

CONCLUSION: 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.