Fig. 1.

Protocol diagram for study visits. Blood sampling was done every 10 min for serum LH and FSH for 240 min. After 1 h of baseline blood sampling, infusions of kisspeptin-54, GnRH, or vehicle were commenced. The initial infusion rate was doubled for the first 30 min to achieve steady-state levels more rapidly. Maintenance infusion rates were 0.1, 0.3, and 1.0 nmol/kg/h of each peptide. Each participant received the same dose of each peptide (kiss­peptin-54 or GnRH) in random order at least 1 week apart (n = 5 per dose). FSH, follicle-stimulating hormone; GnRH, gonadotropin-releasing hormone; LH, luteinising hormone.