Kisspeptin-10 Peptide for GnRH Stimulation & Fertility Research

The biological processing of full-length kisspeptin proteins results in Kisspeptin-10 as their smallest active fragment. The decapeptide acts on the kisspeptin receptor (KISS1R) on the surface of hypothalamic GnRH neurons to rapidly and in a dose-dependent manner, to trigger a release of GnRH followed by the downstream release of luteinizing hormone and follicle-stimulating hormone. The short sequence retains in-vivo activity, but with the added advantages of synthetic tractability and a shorter half-life, kisspeptin-10 can be more easily controlled temporally for experimental manipulations. In recent years, the use of kisspeptin-10 to study the timing of puberty, to simulate ovulation, and to investigate potential therapeutic avenues for hypogonadotropic hypogonadism has become increasingly common. The scope of such investigations is, however, confined to basic research, and the molecule has no accepted clinical use in humans.

Fig. 1 Amino acid sequences of kisspeptin 10 (KP-10) analogs.^1,2

Introduction to Kisspeptin-10

Kisspeptin-10 is the highly conserved C-terminal activation domain shared among all native kisspeptin variants in vertebrates. Binding of the peptide to the endogenous G-protein-coupled receptor results in Gαq/11-dependent phospholipase C activity and subsequent intracellular calcium waves to pace GnRH neuronal burst activity. The ensuing episodic release of the neuropeptide is recognized by the anterior pituitary as a pulsatile signal that is faithfully reflected in the episodic secretion of LH and FSH and, in this way, recapitulates the pulsatile nature that controls gamete production and steroid production. As the decapeptide lacks any PTMs other than C-terminal amidation, it can be synthesized with high purity via standard solid-phase peptide synthesis (SPPS) approaches, whereas glycoform micro-heterogeneity and folding isomers present a challenge for longer peptides. The relatively short plasma half-life of the native peptide is also advantageous because stimulating episodes of relatively short duration can be administered and withdrawn within a relatively short period. This feature is particularly useful for studying acute effects such as oocyte maturation priming or steroidogenic enzyme gene induction because of the reduced carry-over effects seen with long-acting depot preparations. The key advantage of kisspeptin-10, however, is that it, like all kisspeptins, has complete cross-species receptor recognition and, in this way, direct translation of rodent findings to other mammalian species, and, ultimately, to ex-vivo human hypothalamic slice studies. In sum, these properties make the peptide a highly valuable tool for understanding the molecular code that links neural command to reproductive output.

Molecular Profile

Kisspeptin-10 is a linear, amidated decapeptide with the amino-terminal sequence Tyr-Gly-Leu-Met-Gln-Thr-Pro-Ser-Phe-Gly-Arg(Phe)NH2. The C-terminal arginine–phenylalanine–amide tripeptide is the pharmacophore necessary for high-affinity binding. Kisspeptin-10 is relatively hydrophilic and has a net positive charge at physiological pH, and thus can electrostatically interact with the extracellular loops of KISS1R. It is predicted to adopt a partial type-I β-turn structure centred on the –Ser–Phe–Gly– motif, which is conserved among all kisspeptin sequences. This conformation places the key aromatic side chains in the correct orientation to dock into the receptor binding site. It can be synthesized by standard Fmoc solid-phase peptide synthesis methods. Side-chain protecting groups should be chosen to reduce the risk of racemization of the C-terminal arginine. Cleavage and deprotection should be followed by purification by reverse-phase HPLC to homogeneity. The pure white, non-hygroscopic acetate salt is stable for months when lyophilized and stored under dry conditions at −20 °C. In aqueous solution, kisspeptin-10 is prone to cleavage by chymotrypsin-like enzymes after the phenylalanine residue and is also prone to oxidative modification of its single tryptophan residue; therefore, formulations often include mannitol or trehalose as a lyoprotectant, and a small amount of ascorbate as an antioxidant to scavenge free radicals. The monoisotopic mass of purified kisspeptin-10 measured by mass spectrometry is in agreement with the expected mass. The circular dichroism spectra demonstrate that the structure maintains random-coil conformation in buffer but changes into a folded form when it interacts with membranes. Absence of disulphide bridges or post-translational modifications (PTMs) other than C-terminal amidation makes the molecule easily metabolically traced and less subject to batch-to-batch heterogeneity for multi-center studies.

Research-Specific Use Only Notice

Kisspeptin-10 is provided as a research tool only and is not for human or veterinary clinical use. Approval for animal studies must be granted by your animal-care committee before in-vivo administration and researchers should follow standard safety practices when handling bioactive peptides. Prepare a fresh, sterile-filtered (0.22 µm), aliquoted stock solution that is used within one experimental procedure. Ensure dosing volumes are adjusted for small test animals and small doses are titrated using the minimum number of animals to determine the lowest effective dose before increasing the animal number. This may also be necessary for pharmacokinetic/pharmacodynamic analysis, as kisspeptin-10 is cleared fairly rapidly from the circulation (half-life is in the minutes range in most species). As kisspeptin-10 induces a pulsatile secretion of GnRH, it is useful to measure circulating LH at the same time to verify on-target activity and to limit overstimulation of the axis and subsequent loss of subtle experimental effects. Unused reagent and experimental animal waste should be disposed of according to local standards for cytotropic peptides. When publishing experiments that use kisspeptin-10, please specifically note it was used as a research tool, to help prevent non-approved use.

Role in Fertility Research

Kisspeptin-10 has come to occupy a conceptual center stage in modern fertility research because it represents a minimally invasive means to both time and titrate the entire hypothalamic–pituitary–gonadal conversation. This decapeptide, which faithfully mimics the natural signal for GnRH release, allows investigators to experimentally reproduce, disrupt or phase-shift reproductive cycles without necessitating any permanent structural modifications to the underlying anatomy. Translational studies employ this approach to investigate system functionality in silent axes, explore metabolic factors that delay puberty, and determine if anovulation stems from hypothalamic inactivity or pituitary unresponsiveness. Its short length and rapid enzymatic degradation mean that single or repeated doses can be administered over the course of a single study visit, a logistical advantage when working with large animal models or with human volunteers for whom prolonged stimulation would be unethical. In contrast, continuous exposure paradigms can be used to characterize the plasticity of the pulse generator and the circumstances under which receptor desensitization or tachyphylaxis ensues, an essential step before any long-term therapeutic strategy can be contemplated. The peptide thus serves as diagnostic provocateur and as a mechanistic probe all rolled into one, affording a common language that bridges bench observations and clinical phenomenology and back again.

Impact on GnRH and LH Release

A short-duration injection of kisspeptin-10 is readily absorbed into the portal blood stream where it activates the GnRH secretory machinery, a central nervous event that is heralded by a characteristic LH pulse of amplitude and frequency that are dependent on the background steroid environment. The effect of kisspeptin-10 injection on the GnRH neurons arises because the decapeptide stimulates GPR54 on the somatodendritic membrane of these neurons, leading to a biphasic Ca2+ signal that involves voltage-dependent and calcium store-dependent pathways. The ensuing depolarization of these neurons results in their firing and, given the sparse and scattered distribution of GnRH neurons, this can be monitored in real-time using GCaMP transgenic mice, an effect that is temporally associated with the sudden onset of LH in the circulation. The peptide also is important in entraining GnRH/LH pulses so that later episodes of LH secretion are better synchronized, an action that has made the peptide useful for re-synchronizing a dysregulated or seasonally suppressed reproductive axis. The kisspeptin signal is short lived, due to rapid endocytosis and peptide degradation, so when the exogenous stimulus is removed the axis is able to re-establish its own intrinsic pulsatility, a strategy that provides a means of acute experimental manipulation that is far less encumbered than the ethical and physiological issues associated with implantable drug delivery devices. In females, the same challenge reveals the positive feedback threshold that is crossed just before ovulation. In contrast, in males, the kisspeptin-10 injection unmasks the steroidogenic reserve of Leydig cells. These observations have provided a common conceptual framework to interpret the otherwise sex-dimorphic response to kisspeptin-10 and the most direct pharmacological approach currently available to interrogate the neural basis for failed or arrhythmic LH pulsatility across a wide range of physiological and pathophysiological states.

Applications in Infertility Studies

One of the early applications of kisspeptin-10 in infertility research was as a non-invasive stress test to determine if the hypothalamic–pituitary–gonadal axis is temporarily quiescent or permanently atrophic. In patients with functional hypothalamic amenorrhoea, a single administration can often restore a normal pattern of LH pulsatility, allowing clinicians to differentiate between a reversible metabolic suppression and anatomic lesions and whether to proceed with nutritional, psychological, or pharmacological intervention. In men with idiopathic normogonadotropic oligozoospermia, the test can be used to determine if Sertoli cell support is due to a lack of gonadotropin stimulation or testicular failure, which in turn leads to either the use of empiric hormonal stimulation or to the initiation of assisted reproductive therapy. The peptide has also been incorporated into protocols that simulate polycystic ovary syndrome; an enhanced and prolonged LH release in response to kisspeptin-10 is consistent with an inherently faster pulse generator, while it can be co-administered with purported antagonists to assess potential treatment approaches under physiologic conditions. The fragment has been used as a priming agent in gamete maturation studies in order to coordinate follicular waves or spermatogenic cycles, and the timing of oocyte maturation or epididymal transit can be studied without the need for exogenous gonadotropin combinations that alter physiologic feedback mechanisms. In all of these applications, the short half-life of kisspeptin-10 is a safety benefit because any potential overstimulation is transient and the next cycle can be studied without carry-over effects. This is particularly desirable when multiple observations are needed within the same population.

Comparative Endocrine Pharmacology Across Physiological States

Metabolic state, reproductive status and emotional state also alter the texture of the kisspeptin-10 response. In fasted animals or subjects, the same dose that elicits a rapid increase in controls results in a delayed and attenuated peak. Leptin, insulin, and ghrelin thus regulate kisspeptin neuron excitability via AMP-activated protein kinase and mammalian target of rapamycin signaling. In seasonal breeders, the same injection during anoestrus is not sufficient to recruit enough GnRH neurons to trigger an increase in LH. In the reproductive period, the same dose of kisspeptin-10 recruits more GnRH neurons and elicits a series of pulses that can result in ovulation. Kiss-1 gene promoter methylation is, therefore, an epigenetic mechanism that regulates seasonal reproduction. During pregnancy, there is an increase in placental steroids that impose a slow tonic, rather than a pulsatile, hypothalamic release. In this environment, kisspeptin-10 challenges also elicit a plateau-type LH response, recapitulating the neuroendocrine environment that characterizes the maintenance of the corpus luteum. On the other hand, the absence of the amplitude in response to kisspeptin-10 in aged rodents is due to a reorganization of afferent connections to kisspeptin neurons that normally potentiate the calcium peak, as reported in ex vivo brain slices. This finding may underlie the molecular basis of reproductive senescence.

Technical Data

The description of kisspeptin-10 quality controls was made in a qualitative way, in order to allow the user to transcribe it on his or her own instrumental range, and to avoid being "locked" to a single set of numbers which could quickly become outdated due to a new instrumental setup. Visually, the dry powder should appear as a white or off-white, non-hygroscopic cake, breaking under low stress. This is related to its very poor residual secondary and tertiary structure, and allows for a quick reconstitution. The reconstituted solution should be a clear, colorless to faintly opalescent liquid, with no suspended particles, as detected by visual inspection at an angle to the light source. However, any residual or slow precipitation or clouding would either indicate incomplete solvent wetting of the solid, or, more worryingly, initial aggregation, which could lead to false positives in receptor binding assays. Product purity is indicated by a single, dominant, symmetrical peak during reversed-phase separation with low acetonitrile conditions, with no sign of hydrophilic or hydrophobic truncations (earlier or later, respectively). Mass is then assessed based on the expected protonated molecule, with a window that is narrow enough to exclude common oxidation (methionyl) or deamidation (asparaginyl) species, but broad enough to account for the isotopic envelope. Endotoxin level is assessed by measurement of limulus amoebocyte lysate (LAL) reactivity, which should not exceed a level that, although not specified in EU/mg in this document, is considered non-pyrogenic for even very sensitive mouse strains in the periphery. Sterility is assumed after direct inoculation of a reconstituted sample into aerobic and anaerobic broths, followed by a lengthy incubation at room temperature and at an elevated temperature, with any resulting turbidity being grounds for rejection. Taken together, these characteristics provide a qualitative "basket" that follows each batch and will not become outdated, while still allowing for interpretation of the data in different labs.

Purity, Storage, Recommended Concentrations

Its purity must be validated by orthogonal separation methods, not a single number. In ion-pairing reverse-phase HPLC, there should be one major symmetric peak, with no late-eluting oxidation products or early-eluting deletion species at the trailing edge. The dry substance should be stored in a light-resistant vial with an O-ring cap, over a desiccant, at 2–8 ˚C to prevent Maillard or other condensation reactions. Long term storage may be done in an inert-gas glovebox purged with dry nitrogen, to prevent oxidation of the methionine residue, which could show up as an extra late-eluting peak many months after release. The reconstituted solution should be considered a labile biomolecule, and aliquoted in thin-walled tubes or vials to maximize surface area/volume and achieve rapid freezing. Freeze-thaw cycles should be avoided. Aliquots are thawed only once, under refrigerated conditions. The vial is briefly vortexed, to eliminate temperature gradients, and then added to the experimental preparation without further dilution, to avoid introducing endotoxin from glassware or solvent stocks. The concentration of PACAP-38 is not standardized, but depends on the buffering capacity of the receptor. Stock solutions are typically prepared at a concentration that can be diluted at least 10-fold into the final perfusate solution, so that the concentration of acetic acid or DMSO vehicle is unlikely to alter neuronal firing rates. Working dilutions are made in phosphate-buffered saline that has been pretreated with a mixed-bed ion-exchange resin to remove heavy metals. The solution is then filter-sterilized through a low-protein-binding 0.22 µm pore filter. The final concentration range should be bracketed in a pilot experiment, starting just above the baseline and increasing until the curve flattens, without reaching supraphysiological concentrations that may cause receptor desensitization or non-selective pressor responses.

Lyophilization Behavior and Reconstitution Rheology

In addition to chemical considerations, the physical form of kisspeptin-10 as a lyophilized cake also determines how easily and reproducibly the researcher can prepare a solution for biological experiments. The lyophilized peptide has a eutectic composition, which results in an amorphous glass rather than a crystalline material. This preserves the sequence of the peptide from shear forces during the lyophilization process but is hygroscopic. Collapse temperature is critical during lyophilization; if this temperature is exceeded even briefly, the solution will undergo viscous flow and any water present will become trapped, and phase separation can occur within the vial resulting in a sticky pellet that cannot be dissolved by a solvent. Reconstitution of the lyophilized peptide is not simply a matter of convenience but is part of the quality of the material: an ideal lyophilized cake should crumble in a few seconds when the vial is rotated gently, and the liquid should run up the wall of the vial forming a continuous film rather than discrete droplets that would indicate surface tension or hydrophobicity. The choice of solvent also affects the rate of wetting; a buffered isotonic saline solution with a small amount of volatile cosolvent such as tertiary-butanol reduces surface tension without changing osmolality, and can result in instantaneous dissolution without the foaming that can occur with vigorous shaking. The resulting solution should be Newtonian at shear rates seen during syringe injection; non-Newtonian, shear-thinning behavior is indicative of self-association into oligomeric β-sheet structures, which may sequester receptor-active monomers. To avoid aggregation, the pre-cooled solvent is added along the wall of the vial rather than directly to the cake to reduce local high concentrations that can nucleate fibrillation. A qualitative check can be to inspect the solution under cross-polarized light: flashes of birefringence are indicative of early β-sheet structures before the solution is visibly turbid, and can allow the researcher to identify and dispose of a bad aliquot before it is used on live tissue. In this way, an understanding of the subtleties of lyophilization and reconstitution is critical to ensure that the biological read-out is due to the intended molecular pharmacology and not artefactual colloid chemistry.

Order Kisspeptin-10 & Explore Custom Synthesis Services

Our Kisspeptin-10 peptide is produced to the highest laboratory standards, ensuring high purity verified by HPLC and mass spectrometry. Designed for research use only, it has become a key reagent in studies on GnRH stimulation, LH release, and fertility regulation. For researchers requiring specialized formats, our custom peptide synthesis services provide flexibility to adjust peptide length, modifications, or bulk quantities. Whether you are running pilot studies or large-scale fertility research projects, we deliver Kisspeptin-10 tailored to your experimental needs. Take the next step in advancing your reproductive biology research with our premium Kisspeptin-10 peptide. Contact us today to request a customized quotation, bulk order details, or technical guidance. We provide secure worldwide delivery and reliable customer support, helping scientists access the Kisspeptin-10 they need-fast and with guaranteed quality.

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Frequently Asked Questions (FAQs)

1. Is Kisspeptin-10 available for human use?

No. Our Kisspeptin-10 is for laboratory research only and is not intended for clinical or veterinary use.

2. What applications is Kisspeptin-10 best suited for?

It is primarily used in studies focusing on GnRH stimulation, LH release, and fertility research, including IVF-related investigations.

3. Can I order Kisspeptin-10 in large quantities?

Yes. We support bulk orders for universities, pharmaceutical companies, and research institutes, ensuring consistent quality across batches.

4. Do you offer peptide modifications?

Absolutely. Our custom synthesis service allows for modifications such as labeling, sequence variations, or formulation adjustments to fit your research protocols.