Figure 1.

Protocol diagram for study visits in healthy male subjects. Blood samples taken every 10 min from t = 0 to t = 240 min for serum LH and FSH. Blood samples were also taken for plasma kisspeptin IR at t = 0, 60, 70, 80, 90, 120, 180 and 240 min. After 1 h of baseline blood sampling, the infusions of vehicle, kisspeptin-10, kisspeptin-54 or GnRH were commenced. Maintenance infusion doses were 0.1, 0.3 and 1.0 nmol/kg/h of each peptide. Each participant received the same dose of each peptide in random order at least 1 week apart (n = 5/group).