A Kiss to drive rhythms in reproduction

Reproduction, like many other biological functions, exhibits marked daily and seasonal rhythms in order to anticipate and adapt breeding activity to environmental challenges. In recent years, studies investigating the neuroendocrine mechanisms driving rhythms in reproduction have unveiled the pivotal role of hypothalamic neurons expressing kisspeptin in integrating and forwarding daily and seasonal cues to the reproductive system. The objective of this review is to summarize the knowledge on the effect and role of this neuropeptide on the mammalian hypothalamo‐pituitary‐gonadal axis and describe how it is involved in the daily control of ovulation in females and long‐term adaptation of reproduction in seasonal breeders. In mammals, reproductive activity displays regular daily and ovarian (in female) and seasonal (in both sexes) rhythms. This review discusses how kisspeptin expressing neurons of the hypothalamus, known as potent activator of GnRH neurons, integrate daily and seasonal time cues to synchronize reproductive activity to the geophysical cycles.