Neuroendocrine responses to exogenous estrogen: no differences between heterosexual and homosexual men

Plasma LH concentrations were determined in 55 men before and for four days following injection of 10 mg, 20 mg, or 30 mg Premarin or a placebo injection of vehicle. Testosterone (T) and dihydrotestosterone (DHT) concentrations were also determined in plasma samples taken just prior to Premarin or placebo injection and in samples taken three days later. All subjects provided self-descriptions of their sexual orientation and, based upon these descriptions, were classified as heterosexual (N = 39) or homosexual (N = 16). Premarin injection resulted in a reliable reduction in plasma LH 24 hr later. In subsequent samples, LH values rose and in many cases exceeded baseline levels, most reliably in those subjects receiving the 10 mg dose. Contrary to some previous reports, we observed no significant differences between heterosexual and homosexual subjects in the likelihood of their exhibiting elevated LH concentrations following exogenous estrogens. T, but not DHT, concentrations were suppressed after Premarin injection in both groups of subjects. Other than Premarin dosage, we could not identify any variable which predicted the likelihood of elevated LH values.