Divergent Effects of the Antiestrogen Tamoxifen and of Estrogens on Luteinzing Hormone (LH) Pulse Frequency, But Not on Basal LH Levels and LH Pulse Amplitude in Men

We studied the role of estrogens on LH pulse modulation in men in two ways. Firstly, we compared LH pulse frequency and amplitude in 13 normal men before and after 6 weeks administration of the antiestrogen tamoxifen (10 mg twice daily). Secondly, we compared LH pulse frequency and amplitude between a group of 10 agonadal men not receiving sex steroid treatment and a group of 9 agonadal men (male to female transsexuals) continuously treated with 50 ng ethinyl estradiol/day. Tamoxifen administration to normal men resulted in a significant rise in the mean serum LH level from 5.7 ± 1.3 (± SD) to 10.1 ± 2.4 U/L, which was associated with significant increases in LH pulse frequency (from 4.2 ± 1.5 to 5.8 ± 1.7/7 h) and LH pulse amplitude (from 3.8 ± 0.9 to 4.6 ± 0.7 U/L). In the group of agonadal men the mean LH pulse frequency was 6.8 ± 1.5/7 h, while it was 5.9 ± 1.7/7 h in the estrogen-treated agonadal group (P = NS). The mean serum LH level and LH pulse amplitude were, however, significantly lower in the ...