Kisspeptin-10 is a natural peptide that talks to a brain receptor (GPR54) and can turn on the reproductive hormone system, raising levels of LH and FSH. It was first found as a gene that blocks cancer spread, but now we know it mainly helps control puberty and fertility. Giving kisspeptin (either into the brain or the bloodstream) quickly boosts these hormones in animals, and the system is tuned by the body's own sex hormones.

The kisspeptins are the peptide products of the KiSS-1 gene and the endogenous agonists for the GPR54 receptor. Although KiSS-1 was initially discovered as a metastasis suppressor gene, recent evidence suggests the kisspeptin/GPR54 system is a key regulator of the reproductive system. Disrupted GPR54 signalling causes hypogonadotrophic hypogonadism in rodents and man. Central or peripheral administration of kisspeptin potently stimulates the hypothalamic-pituitary-gonadal axis, increasing circulating gonadotrophin concentrations in a number of animal models. These effects appear likely to be mediated via the hypothalamic gonadotrophin-releasing hormone system, although kisspeptins may have direct effects on the anterior pituitary gland. Hypothalamic KiSS-1 expression is regulated by circulating sex steroids. The precise physiological role of the kisspeptin system in the regulation of reproductive function remains to be elucidated.