Figure 1.

Study protocol diagram. Five healthy women underwent a 1-way crossover protocol. Twice-daily injections of saline and kisspeptin-54 (KP54) were administered between days 7 and 14 during months 1 and 2 of the protocol, respectively. During each month of the protocol, subjects underwent a baseline GnRH test (day 1) and 8-hour blood sampling (day 6) before commencing injections. During the injection period (days 7–14), subjects underwent a 4-hour study (day 7) and two additional 8-hour studies (days 11 and 14) immediately after injection of saline or kisspeptin-54. A GnRH test was performed 24 hours after cessation of saline or kisspeptin treatment (day 15). USS denotes ultrasound examination and measurement of reproductive hormones. Day 1 was defined as the first day of menstrual bleeding.