We have been studying the function and morphology of kisspeptin, a new "main player" in the reproductive regulatory system, and its containing neurons, using histochemical and molecular biological techniques. The results include the relationship between energy metabolism and the reproductive regulatory axis, subtypes of sex hormones and their functions, distribution of kisspeptin-related peptides in the brain and their functions, effects of the maternal-fetal environment on postnatal development based on the Dohad theory, changes in reproductive regulatory mechanisms in animal models of diabetes mellitus, and the effects of kisspeptin on kisspeptin neurons. We have achieved a wide range of research accomplishments.