Serum gonadotrophin levels in prepubertally castrated male sheep treated for long periods with propionated testosterone, dihydrotestosterone, 19-hydroxytestosterone or oestradiol.

At different times of the year, groups of wethers were treated with 20 mg testosterone, dihydrotestosterone or 19-hydroxytestosterone propionates/day or 2 mg oestradiol dipropionate/day, or the oil vehicle, for 6 weeks after a 2-week control period. LH and FSH values were determined by radioimmunoassay of serum samples collected at regular intervals. Oestradiol and dihydrotestosterone reduced LH and FSH concentrations whereas 19-hydroxytestosterone and testosterone had no effect.