Kisspeptin neurons as an integration center of reproductive regulation: Observation of reproductive function based on a new concept of reproductive regulatory nervous system

BACKGROUND: Regulation of the reproductive system has been explained by the actions and feedback of gonadotropin releasing hormone‐luteinizing hormone/follicle stimulating hormone (GnRH‐LH/FSH) ‐sex steroids; however, the discovery of kisspeptin neurons and a kisspeptin‐GnRH‐LH/FSH axis has prompted this regulation to be reviewed. METHODS: We investigated changes in kisspeptin neurons and associated changes in the hypothalamic‐pituitary‐gonadal (HPG) axis under various situations and experimental conditions using histochemical methods. MAIN FINDINGS (RESULTS): Kisspeptin neurons play an important role in receiving and integrating information from internal and external environmental factors and communicating it to the conventional HPG axis. CONCLUSION: The recently described Kisspeptin‐GnRH‐LH/FSH‐gonad system regulates reproductive function via mechanisms that until recently were not completely understood.