Kisspeptin

Kisspeptin refers to a family of naturally occurring peptides produced from the human KISS1 gene. Its research history began with the identification of KISS1 in melanoma metastasis studies, before researchers discovered that its peptide products activate the receptor now called KISS1R, formerly GPR54.¹ ² The best-studied forms, kisspeptin-54 and kisspeptin-10, share a receptor-activating C-terminal sequence but differ in length and biological exposure.² Human genetic studies later linked impaired KISS1R function to disrupted puberty, establishing the pathway’s importance in reproductive development.³ Clinical research subsequently examined gonadotropin secretion, reproductive-hormone responses and experimental oocyte maturation during IVF.⁴ ⁵ These findings place kisspeptin upstream of GnRH, LH and FSH rather than identifying it as a replacement for those hormones. Kisspeptin remains investigational, and findings for one peptide form or study population should not automatically be generalized to another. Its history therefore connects an initial discovery in cancer biology with a well-supported role in reproductive signaling and continuing investigation of potential clinical applications.

Kisspeptin binds KISS1R, a G-protein-coupled receptor expressed by many gonadotropin-releasing hormone neurons in the hypothalamus.² ⁶ Receptor activation primarily engages Gq/11 proteins and phospholipase C, generating intracellular signals that involve IP3, calcium and changes in membrane ion-channel activity. These processes excite GnRH neurons and support GnRH release, with the detailed cellular evidence drawn mainly from animal experiments.⁷ GnRH then enters the hypothalamic-pituitary portal circulation and stimulates anterior-pituitary gonadotrophs to release LH and FSH. Those hormones subsequently act on the ovaries or testes. Human studies support downstream gonadotropin responses, while their magnitude depends on peptide form, reproductive state and administration pattern.⁴ Frequent repeated administration has also produced diminished responses in a small clinical study.⁸ Kisspeptin therefore follows the pathway KISS1R → Gq/11–PLC/calcium signaling → GnRH → LH and FSH → gonadal responses. Its action depends on a responsive reproductive axis and operates within a system shaped by hormonal feedback and pulsatile signaling.