Fig. 1.

Mean (± SD) 10-min profiles of luteinizing hormone (LH) (left two columns) and testosterone (T) (right two columns) concentrations over 10 h in 19 healthy men during overnight gonadotrophin-releasing hormone (GnRH) antagonist (ganirelix) administration. Ganirelix injection was followed by intravenous infusion of saline (top left) and recombinant human (rh)LH continuously (top right), rhLH pulses every 2 h (bottom left), or every 1 h (bottom right) at the same total dose of rhLH (see methodology). Sample zero (x axis) was obtained at 0100 h, which is 6 h after ganirelix injection.