Kisspeptin (KiSS-1) the product of the gene Kiss1 is a G-protein coupled receptor ligand for GPR54.  Kiss1 was originally identified as a human metastasis suppressor gene that has the ability to suppress melanoma and breast cancer metastasis. It is recently become clear that kisspeptin-GPR54 signaling has an important role in initiating GnRH secretion at puberty, the extent of which is an area of ongoing research.  The receptor for kisspeptin, GPR54, was first identified as an orphan GPCR in rat in 1999. Following in 2001, a natural ligand for GPR54 was discovered, which was the product of the Kiss1 gene, originally identified as a human metastasis suppressor gene. Subsequent mutant studies led to the discovery that LOF mutations in GPR54 causes failure to progress through puberty in man, due to hypogonadotropic hypogonadism. Thus, it was concluded that Kisspeptin-GPR54 signaling is essential to initiate gonadotropin (LH/FSH) secretion at puberty.

Kisspeptin neurons reside in nuclei such as Arc and AVPV and send projections into the MPOA, where there is an abundance of GnRH cell bodies. This anatomical evidence suggests that Kisspeptin fibers appear in close anatomical relationship to GnRH (parvicellular) neurons. In fact, Kisspeptin appears to act directly on GnRH neurons (via GPR54) to stimulate the secretion of GnRH.

However, for kisspeptin to be involved in the regulation of GnRH release, it must also be sensitive to steroid levels within the circulation, as it has already been established that steroids produced by the gonads exert regulatory effects on FSH and LH levels through GnRH mediation. Therefore, there are (at least) two possible scenarios: That either kisspeptin neurons express steroid receptors (such as ERα, ERβ, and AR) themselves, or they receive input from another mechanism about circulating steroid levels.