Kisspeptin-10: the chocolate-named gene that switches on puberty

A cancer gene with a sweet name

Few hormones have a story as unlikely as this one. Kisspeptin was found by cancer researchers looking for genes that stop melanoma from spreading. It was named, in part, after a chocolate. And it ended up explaining one of biology's longest-standing puzzles: what flips the switch that starts puberty.

Today kisspeptin-10, the shortest active form, is used to probe that switch in people ^[6-8]. Kisspeptins have been tested in healthy volunteers, in fertility clinics and inside brain scanners. Each line of work tells part of the story, and each has limits worth understanding.

From Hershey to the hypothalamus

In 1996, Danny Welch's group at the Pennsylvania State University College of Medicine in Hershey reported a new gene from melanoma cells ^[1]. When they inserted human chromosome 6 into aggressive melanoma cells, the cells lost at least 95% of their ability to metastasise, though they still formed tumours ^[1]. Hunting for the responsible gene, they found one that was switched on only in non-metastatic melanoma cells, and that suppressed metastasis when put back into aggressive cells ^[1].

They called it KiSS-1. The name signalled that the gene encoded a metastasis "suppressor sequence", and nodded to the town's most famous product, Hershey's chocolate Kisses ^[2].

For five years, what the gene actually made remained unclear. Then, in 2001, researchers isolated the peptides it produces from human placenta: fragments of 54, 14 and 13 amino acids sharing the same tail, which they named kisspeptins ^[3]. These peptides switched on an "orphan" receptor called GPR54, which is abundant in the placenta and the pituitary gland ^[3].

The decisive clue came from families, not from cancer: in 2003, two teams independently found that people with broken GPR54 receptors never went through puberty ^[4,5].

In Boston, Stephanie Seminara and colleagues studied a family in which several members lacked pubertal development and found a single amino-acid change (L148S) in GPR54; mice engineered to lack the receptor were also sexually immature ^[4]. In France, Nicolas de Roux's team found a deletion in the same gene in five affected siblings ^[5]. Overnight, a melanoma gene became a central player in reproductive biology.

How kisspeptin turns the key

Reproduction is run by a chain of command. Nerve cells in the hypothalamus release gonadotropin-releasing hormone (GnRH) in pulses. GnRH tells the pituitary to release luteinising hormone (LH) and follicle-stimulating hormone (FSH), which in turn drive the ovaries and testes.

Kisspeptin sits above GnRH. If GnRH is the ignition key of the reproductive system, kisspeptin is the hand that turns it: kisspeptins stimulate GnRH and therefore LH and FSH release ^[6]. They act through GPR54 (now also called KISS1R), and without a working receptor normal GnRH physiology and puberty fail ^[4,5].

All kisspeptins share the same C-terminal end, finished with an amide group ^[3]. Kisspeptin-10 is just that last stretch of ten amino acids, and it is the minimal sequence with full intrinsic activity at the receptor ^[6].

What the research shows

Kisspeptin-10 in men

Kisspeptin-10 had not been studied in people until a 2011 dose-response study in Edinburgh ^[6]. In healthy men, a single intravenous bolus roughly tripled blood LH within 30 minutes (from 4.1 to 12.4 IU/L in the best-responding dose group of six men) ^[6]. A continuous infusion lasting 22.5 hours raised testosterone from 16.6 to 24.0 nmol/L and increased LH pulse frequency from 0.7 to 1.0 pulses per hour ^[6]. Notably, the highest bolus dose gave a smaller response than a moderate one ^[6].

A surprising difference in women

Imperial College London researchers then compared men and women ^[7]. In healthy men, kisspeptin-10 raised LH and FSH even at low doses. In women in the early (follicular) phase of the menstrual cycle, it produced no change in these hormones at any dose tested, by injection or infusion ^[7]. Only in women close to ovulation did it raise LH and FSH ^[7]. Groups were small, with four or five people each.

Longer exposure

A 2026 Imperial study asked whether kisspeptin-10 could keep working over days ^[8]. In 15 healthy men, with 12 serving as controls, a continuous five-day infusion kept testosterone up but let LH and FSH fall back to placebo levels, a sign of desensitisation ^[8]. Daily eight-hour infusions over 12 days, by contrast, sustained increases in reproductive hormones, and the receptor still responded at the end ^[8].

IVF: triggering egg maturation

In IVF, eggs need a final hormonal push to mature before collection. IVF also carries a risk of ovarian hyperstimulation syndrome (OHSS), a potentially life-threatening over-reaction of the ovaries ^[10]. Imperial researchers tested kisspeptin as an alternative trigger.

In a 2014 study of 53 women, a single injection of kisspeptin-54 matured eggs at every dose tested; 49 women had embryos transferred and 12 achieved a clinical pregnancy (23%) ^[9]. A 2015 phase 2 trial in 60 women at high risk of OHSS reported egg maturation in 95% of them, a live birth rate of 45% per embryo transfer and no cases of moderate or severe OHSS ^[10]. These trials used kisspeptin-54, not kisspeptin-10.

Sex, emotion and the brain

Kisspeptin may also act beyond the hormone chain. In a 2017 study of 29 healthy young men, kisspeptin increased activity in limbic brain areas specifically when the men viewed sexual and couple-bonding images, and it reduced negative mood ^[11].

Two randomised crossover trials then studied people with hypoactive sexual desire disorder (HSDD), each with 32 completers and each using a single 75-minute infusion of kisspeptin-54 ^[12,13]:

These are mechanism studies with brain imaging as the main outcome, not treatment trials. For a different approach to the same condition, see our article on PT-141 (bremelanotide), and for another hormone studied in bonding research, oxytocin.

What we don't know yet

• Kisspeptin-10 versus kisspeptin-54. Most headline human results, in IVF and brain imaging, used the 54-amino-acid form ^[9-13]. They cannot simply be transferred to kisspeptin-10.
• The sex difference. Kisspeptin-10 had no effect on gonadotropins in women early in the menstrual cycle ^[7]; why, and what that means for any use in women, is unresolved.
• Desensitisation. Continuous exposure dampened the LH and FSH response within days ^[8]. The best pattern of exposure, if any, is still being worked out.
• Small, short studies. Most trials involved a few dozen people, often a single dose, and measured hormones or brain activity rather than clinical outcomes. Our guide to levels of evidence explains why that matters.
• The cancer connection. KISS1 was discovered as a metastasis suppressor, yet its role in human cancers appears complex; a 2018 review was titled "KISS1/KISS1R in Cancer: Friend or Foe?" ^[2].
• Long-term safety. No long-term human safety data exist for repeated kisspeptin-10 exposure.

Regulatory status

• Medicine status: we found no approval of kisspeptin-10 as a medicine for any indication; it remains an investigational compound.
• United States: since 29 September 2023 the FDA has listed kisspeptin-10 in "Category 2" of bulk substances nominated for compounding, meaning it may present significant safety risks, citing possible immunogenicity, impurity concerns and limited safety data; it was still listed in the April 2026 update ^[15].
• Sport: the 2024 WADA Prohibited List added kisspeptin and its agonist analogues under S2.2.1, "testosterone-stimulating peptides in males" ^[14].
• European Union: we found no authorised kisspeptin medicine.

In the lab: handling and storage

Kisspeptin-10 (product page) is typically supplied as a lyophilised powder with an amidated C-terminus, as in the natural peptide ^[3]. Store the powder long term at −20 °C, or at 2–8 °C for short periods, protected from light and moisture. The sequence contains tryptophan and tyrosine, which are sensitive to oxidation and light, so vials are best kept sealed and dark. After reconstitution, common lab practice is to keep solutions refrigerated, use them within a short window and avoid repeated freeze-thaw cycles; our guide to storing research peptides has more detail.

FAQ