Establishment ofthe hypothalamic-hypopbyseal-gonadal function ís dependent on the highly controlled and dynamic interactions between regulatory signals from tbe brain, pituitary and gonads, all of them leading to
the attainment of reproductive capacity, where a coordinated and tirnely activation of GnRH neurons jnust occur. The GnRH neurons extend their neurosecretory axons to the hypothalarnus where GnRH is released
into the pituitary portal vessels to elicit the secretion ofLR and FSH, which in turn, will promote gonadal development and support reproductive physiology. Genetic studies have demonstrated that disabling
mutations and targeted deletions ofthe G-protein-coupled receptor (GPR54) generated hypogonadotropic hypogonadism. This link between GPR54 and reproduction, generated attention to the naturaJ ligands of the
GPR54 receptor, known as kisspeptins, which are translational products of the hypothalamic gene KiSSl.
Recent advances in kisspeptin research have defined a major role ofthis molecule in controlling the onset of the reproductive function observed at puberty. The airn ofthis revíew is to highlight the basic endocrine and
genetic concepts involved in theestablishment ofthe hypothalamic-hypophyseal-gonadal axis function which prometes the onset of the reproductive function during puberty. The review highlights what is currently known about the kisspeptin-GPR54 signalling system in the activation ofthe GnRH neurons.