Kisspeptin-10

What is Kisspeptin-10?

Kisspeptin-10 is the biologically active C-terminal decapeptide of kisspeptin, the neuropeptide encoded by the KISS1 gene that sits at the very top of the hypothalamic-pituitary-gonadal (HPG) axis. Loss-of-function mutations in its receptor, GPR54 (now KISS1R), cause hypogonadotropic hypogonadism and absent puberty — the 2003 discovery that made kisspeptin the recognised gatekeeper of reproductive function.

Unlike most research peptides, kisspeptin has a substantial human literature. Intravenous kisspeptin-54 and kisspeptin-10 reliably raise LH, FSH and testosterone in healthy men; kisspeptin-54 has been used as a trigger for egg maturation in IVF; and brain-imaging studies show kisspeptin modulates limbic responses to sexual and emotional stimuli. Kisspeptin-10 is the form most used in the laboratory because it is the shortest fragment that retains full receptor activity.

Molecular Composition

Kisspeptin-10 is a 10-amino-acid amidated peptide, Tyr-Asn-Trp-Asn-Ser-Phe-Gly-Leu-Arg-Phe-NH2 (1,302.45 Da), corresponding to residues 45–54 of kisspeptin-54. The C-terminal Arg-Phe-NH2 (RF-amide) motif is the pharmacophore for KISS1R binding and is shared with the RFamide neuropeptide family (neuropeptide FF, neuropeptide AF). Kisspeptin-10 is rapidly cleaved by endopeptidases in plasma — its half-life is on the order of minutes — which is why clinical studies use continuous infusion or repeated dosing rather than single bolus for sustained effects. Supplied as a lyophilized powder for reconstitution.

How Does It Work?

Kisspeptin-10 is a full agonist at KISS1R (GPR54), a Gαq/11-coupled receptor densely expressed on hypothalamic GnRH neurons. Receptor activation drives phospholipase C, IP3-mediated calcium release and PKC activation, depolarising GnRH neurons and triggering GnRH secretion into the hypophyseal portal system. GnRH then stimulates pituitary gonadotrophs to release LH and FSH, which drive testosterone synthesis in the testes and oestradiol/progesterone production and ovulation in the ovaries.

The response is pulse-shaped: a kisspeptin bolus produces a discrete LH surge, and continuous kisspeptin-10 infusion in men increased LH pulse frequency and raised testosterone. Kisspeptin neurons in the arcuate nucleus (KNDy neurons) are themselves the GnRH pulse generator, integrating oestrogen/testosterone feedback and metabolic inputs (leptin, insulin) — which is why kisspeptin is the molecular link between nutritional state and fertility. Sustained, non-pulsatile exposure can desensitise the axis, an important design consideration in any protocol.

Key Research Pathways

Key Findings from the Literature

• Inactivating GPR54/KISS1R mutations cause hypogonadotropic hypogonadism and absent puberty — genetic proof that the kisspeptin system gates human reproduction (Seminara et al., NEJM 2003; PMID 14573733)
• Kisspeptin-54 IV infusion raised LH, FSH and testosterone in healthy men — the first human demonstration of HPG-axis activation (Dhillo et al., JCEM 2005; PMID 16174713)
• Kisspeptin-10 boluses potently evoke LH secretion in men; 22.5-hour infusion at 4 µg/kg/h raised mean LH from 5.4 to 20.8 IU/L and testosterone from 16.6 to 24.0 nmol/L (George et al., JCEM 2011; PMID 21632807)
• A single kisspeptin-54 injection triggered egg maturation in women undergoing IVF, with live births — a therapeutic proof-of-concept in reproductive medicine (Jayasena et al., JCI 2014)
• Kisspeptin administration enhanced limbic brain responses to sexual and couple-bonding images in healthy men on fMRI (Comninos et al., JCI 2017)
• Kisspeptin-10 stimulated testosterone and LH in men with type 2 diabetes and mild biochemical hypogonadism (George et al., 2013; PMID 23153270)

Important Research Context