What it is
Kisspeptin-10 (KP-10) is a synthetic 10-amino-acid peptide with sequence Tyr-Asn-Trp-Asn-Ser-Phe-Gly-Leu-Arg-Phe-NH₂ (H-YNWNSFGLRF-NH₂), molecular formula C₆₃H₈₃N₁₇O₁₄, molecular weight 1302.45 Da, CAS 374675-21-5. It is the C-terminal decapeptide of metastin (kisspeptin-54), the full-length product of the KISS1 gene. The C-terminal amide is essential for activity. KP-10 is the minimal fragment that retains full agonist activity at the kisspeptin receptor (KISS1R, also called GPR54, AXOR12, or hOT7T175), and binds with roughly 8-fold higher affinity than kisspeptin-54 itself (Ki ~0.042 nM for KP-10 vs ~0.34 nM for KP-54). The KISS1 gene was originally identified as a metastasis-suppressor gene, and its role as the master upstream trigger of mammalian reproduction was established in 2003 when de Roux and Seminara independently linked loss-of-function GPR54 mutations to idiopathic hypogonadotropic hypogonadism.
How it works
- 01
KISS1R / GPR54 agonism on hypothalamic GnRH neurons
KP-10 binds KISS1R, a seven-transmembrane Gq/11-coupled (and secondarily Gi/o-coupled) GPCR expressed on most GnRH neurons. Receptor activation drives phospholipase C–β, IP₃-mediated intracellular calcium release, and diacylglycerol-driven PKC activation. The 2024 Physiological Reviews synthesis (Millar and colleagues, Physiol Rev 2024) consolidates two decades of work showing that kisspeptin–KISS1R signaling is indispensable for hypothalamic–pituitary–gonadal axis function, and that de Roux 2003 and Seminara 2003 independently established the loss-of-function human phenotype — idiopathic hypogonadotropic hypogonadism with absent puberty — that fixed KISS1R as the upstream trigger of the reproductive axis.
- 02
Membrane depolarization via TRPC activation and K⁺ channel inhibition
Patch-clamp work in mouse GnRH neurons (reviewed in Pielecka-Fortuna and colleagues, PMC4019505) shows that KP-10 produces a long-lasting (tens of minutes) depolarization via activation of transient receptor potential canonical (TRPC) nonselective cation channels and simultaneous suppression of A-type, inwardly rectifying (Kir), and G-protein-coupled inwardly rectifying (GIRK) potassium channels. Firing frequency increases 5- to 10-fold without tachyphylaxis over the recording window. This is the direct-excitation mechanism that underlies the rapid LH rise seen within minutes of IV KP-10 in humans.
- 03
KNDy network — the GnRH pulse generator
Kisspeptin / neurokinin B / dynorphin co-expressing (KNDy) neurons in the arcuate nucleus function as the mammalian GnRH pulse generator. NKB stimulates kisspeptin release via NK3R, dynorphin inhibits it via κ-opioid receptors, and the synchronized KNDy burst drives pulsatile kisspeptin output onto GnRH neurons (Clarkson and colleagues, and others, reviewed in the 2024 Physiol Rev synthesis). Optogenetic activation of ARC kisspeptin neurons in vivo produces frank LH pulses in a sex-steroid-dependent manner. KP-10 exogenously administered bypasses the KNDy generator and drives GnRH neurons directly — useful experimentally, but also why exogenous KP-10 cannot fully recapitulate physiologic pulsatility.
- 04
Dual feedback populations — ARC vs AVPV/RP3V
ARC kisspeptin neurons express ERα and are suppressed by estradiol and testosterone (negative feedback — basal gonadotropin tone). AVPV/RP3V kisspeptin neurons in females are stimulated by rising estradiol during the late follicular phase (positive feedback), producing the preovulatory kisspeptin surge onto GnRH neurons that generates the LH surge. GPR54-null and KISS1-null mice fail to show c-FOS induction in GnRH neurons during the LH surge, and loss-of-function humans fail to enter puberty — both confirm the absolute dependence of the surge on kisspeptin signaling.
- 05
Pharmacokinetics in humans — short half-life of KP-10
KP-10 has a plasma half-life of approximately 4 minutes in humans (Chan and colleagues; Jayasena and colleagues), with rapid clearance by peptidases and renal/hepatic elimination. Kisspeptin-54 has a plasma half-life of ~25–30 minutes, and the synthetic analog MVT-602 / TAK-448 extends the effective pharmacodynamic window to roughly 21–22 hours (Abbara 2024). This PK hierarchy is the single most important translational fact about KP-10: it is an excellent acute stimulation probe and a poor chronic-therapy scaffold without re-engineering.
- 06
Emerging, non-reproductive biology — exploratory only
KISS1R expression in some vascular smooth muscle, pancreatic islet, and tumor tissue has driven exploratory work outside reproduction: the 2025 Stroke paper on kisspeptin-10 preventing cerebral aneurysm development in a preclinical model (PMC12086517), DOTA-kisspeptin-10 as a ⁶⁸Ga / ¹⁷⁷Lu pan-tumor radiopharmaceutical scaffold (PMC11919473), and scattered reports on insulin secretion and energy homeostasis. These are mechanistic and preclinical signals — none yet translate to a graded human outcome.