Effect of an antiestrogen on the testicular response to acute and chronic administration of hCG in normal and hypogonadotropic hypogonadic men: Tamoxifen and testicular response to hCG*

Abstract

The effect of the antiestrogen tamoxifen (Tx) on the acute and chronic hCG administration was evaluated in patients with hypogonadotropic hypogonadism (HH) and in normal men. An hCG test (5000 IU hCG) was performed before, after two months of hCG administration (2000 IU hCG three times weekly) and after two months of hCG + Tx (2000 IU hCG three times weekly plus 20 mg/day of tamoxifen). Blood samples were obtained before and following 24 and 72 h of every test to determine T, E, 17OHP and SHBG. T increased only in HH with both treatments (X +/- SEM: Basal: 97.9 +/- 19.7; hCG: 237.7 +/- 43.2; hCG +/- Tx: 204.7 +/- 10.7 ng/100 ml). 17OHP rose with hCG alone, but not with hCG + Tx in both groups. E, SHBG and 17OHP/T ratio did not change after treatments. hCG tests: E increased 24 h following hCG administration in every test. The ratio 17OHP/T rose at 24 h in the first and second test but in the third test it did not change. These results support the role of E in the acute hCG-induced Leydig cell desensitization. However, the association of Tx does not improve T serum levels, suggesting that E might not be the unique factor involved in the mechanisms for testicular desensitization.