Maturation of the clock-timed gonadotropin release mechanism in hamsters: a key event in the pubertal process?

Gonadotropin secretion patterns were monitored in 10, 14 to 21-, and 35-day-old prepubertal female hamsters by RIA. Blood samples were obtained between 1500-1900 h to coincide with the time when the adult female hamster experiences a clock-timed surge in gonadotropin release. Before 16 days of age, the female hamster appears to exhibit a tonic pattern of gonadotropin release. On day 16 and thereafter, the female hamster exhibits a daily surge of gonadotropin release. Around the clock sampling (every 3 h) has shown that this cyclic pattern of gonadotropin release is not present at any time studied in female hamsters younger than 16 days of age, appears to be clock timed, and occurs at the same time of day as the proestrus surge in cyclic adults. The maturation of the clock timed gonadotropin release mechanism may indicate maturation of the reproductive control system, a key event in the pubertal process.