Fig. 4.

Schematic illustration showing a possible mechanism regulating the pubertal augmentation of ARC Kiss1 expression to trigger pulsatile GnRH/gonadotropin secretion. #1, Estrogen strongly suppresses ARC Kiss1 expression via direct and indirect pathways: estrogen-responsive neurons in the POA mediate estrogen negative feedback action to ensure the prepubertal suppression of ARC Kiss1 expression. #2, During the pubertal transition, the sensitivity to the estrogen negative feedback action on ARC Kiss1 expression somehow decreases, which results in an increase in Kiss1 expression, and the subsequent secretion of kisspeptin triggers GnRH/gonadotropin secretion at pubertal onset.