<p>Reproduction is controlled in humans by the hypothalamic-pituitary-gonadal axis [<cite idref="PUB00007352"/>]. A key molecule in this control circuit is the decapeptide luteinising hormone releasing hormone (LHRH), also termed gonadotropin-releasing hormone (GnRH). GnRH is produced by hypothalamic neurones, secreted in a pulsatile manner into the capillary plexus of the median eminence and mediates the release of luteinising hormone and follicle stimulating hormone from gonadotropic cells in the anterior pituitary. The peptide may have additional functions, as LHRH or LHRH-like immuno-reactivity has been found in gonadal tissue, placenta and the central nervous system, and exogenously administered LHRH affects behaviour [<cite idref="PUB00007352"/>].</p><p>The GnRH decapeptide is processed from a larger precursor protein termedprogonadoliberin I, which also contains prolactin release-inhibiting factor I.</p> Gonadoliberin I precursor