Kisspeptin-10

Research Overview

Kisspeptin-10 serves as an essential research tool for investigating reproductive neuroendocrine mechanisms in laboratory settings. This synthetic decapeptide corresponds to the C-terminal 10 amino acids of the kisspeptin peptide family, which includes kisspeptin-54 (metastin), kisspeptin-14, kisspeptin-13, and kisspeptin-10. All kisspeptin peptides share a common C-terminal RF-amide motif essential for KISS1R receptor binding and activation. Kisspeptin-10 represents the minimal sequence retaining full biological activity, making it particularly valuable for structure-activity relationship studies and receptor pharmacology investigations.

The discovery of kisspeptin’s critical role in reproductive function emerged from human genetic studies identifying KISS1R (GPR54) mutations causing hypogonadotropic hypogonadism and absent puberty. Subsequent research established kisspeptin as the most potent known stimulator of GnRH neuron activity, positioning it as a master regulator of the hypothalamic-pituitary-gonadal (HPG) axis. Laboratory studies investigate kisspeptin-10’s effects on GnRH pulse generation, gonadotropin secretion patterns, sex steroid feedback mechanisms, and reproductive state regulation across different physiological conditions.

Research applications extend beyond basic reproductive neuroendocrinology to include puberty onset mechanisms, fertility regulation, reproductive aging, metabolic influences on reproduction, and potential therapeutic applications for reproductive disorders. Kisspeptin-10’s well-characterized receptor binding, signaling mechanisms, and physiological effects make it valuable for diverse experimental approaches investigating reproductive function at molecular, cellular, and systems levels.

Molecular Characteristics

Complete Specifications:

• CAS Registry Number: 374675-21-5
• Molecular Weight: 1,302.5 Da
• Molecular Formula: C₆₃H₈₃N₁₇O₁₄
• Amino Acid Sequence: Tyr-Asn-Trp-Asn-Ser-Phe-Gly-Leu-Arg-Phe-NH₂
• C-Terminal Modification: Amidated (RF-amide motif)
• Receptor Target: KISS1R (GPR54)
• Peptide Classification: Synthetic decapeptide, RF-amide family
• Appearance: White to off-white lyophilized powder
• Solubility: Water, bacteriostatic water, phosphate buffered saline

The decapeptide structure contains several critical features for biological activity. The C-terminal Arg-Phe-NH₂ (RF-amide) sequence represents the essential pharmacophore for KISS1R binding and activation. The phenylalanine residue at position 6 and tryptophan at position 3 contribute to receptor interaction through aromatic stacking interactions. C-terminal amidation is essential for biological activity, with non-amidated peptides showing dramatically reduced potency. The sequence includes both hydrophobic (Trp, Phe, Leu) and polar (Tyr, Asn, Ser) residues creating an amphipathic character important for receptor binding and aqueous solubility.

KISS1R Receptor Pharmacology

Kisspeptin-10 exerts biological effects through selective activation of KISS1R (GPR54), a Gq-coupled G protein-coupled receptor expressed in GnRH neurons and other hypothalamic populations:

Receptor Binding and Activation:

• High-affinity KISS1R binding (IC₅₀ typically 1-10 nM range)
• Equivalent potency to longer kisspeptin fragments at KISS1R
• Gq/11 protein coupling leading to phospholipase C activation
• Rapid calcium mobilization in KISS1R-expressing cells
• IP₃ and DAG generation as second messengers
• PKC pathway activation downstream of receptor engagement

Cellular Signaling Cascades:

• Intracellular calcium elevation through IP₃-mediated release
• Store-operated calcium entry mechanisms
• ERK1/2 MAPK pathway activation
• PI3K/Akt signaling engagement
• mTOR pathway modulation in some cell types
• cAMP pathway potential cross-talk effects

Receptor Expression Profile:

• High expression in arcuate nucleus kisspeptin neurons
• Expression in anteroventral periventricular nucleus (AVPV/PeN)
• GnRH neuron expression critical for reproductive function
• Peripheral expression in gonads, pancreas, adipose tissue
• Expression in vascular endothelium and placenta
• Species-specific expression pattern variations

These signaling mechanisms underlie kisspeptin-10’s potent effects on GnRH neuron activation and subsequent reproductive hormone cascades.

Pharmacokinetic Profile in Research Models

Kisspeptin-10 pharmacokinetic characterization in preclinical research reveals important properties for experimental design:

Absorption and Bioavailability:

• Intravenous bioavailability: 100% (reference route)
• Subcutaneous bioavailability: Variable depending on formulation
• Rapid absorption from subcutaneous injection sites
• Poor oral bioavailability due to peptide degradation
• Blood-brain barrier penetration limited (peripheral administration affects central targets)
• Intranasal administration investigated for direct CNS delivery

Distribution and Metabolism:

• Rapid distribution phase following IV administration
• Volume of distribution suggests extravascular distribution
• Plasma protein binding moderate (approximately 60-70%)
• Primary metabolism via peptidase degradation
• Rapid enzymatic cleavage at peptide bonds
• Metabolites generally inactive at KISS1R

Elimination Characteristics:

• Plasma half-life: Typically 2-5 minutes in rat models
• Clearance primarily through renal and hepatic routes
• Rapid degradation by serum peptidases
• Biological effects often persist beyond plasma presence
• Suggests receptor binding persistence or downstream signaling amplification
• Multiple administration or continuous infusion protocols employed for sustained effects

These pharmacokinetic properties inform research protocol design, particularly regarding dosing regimens, sampling times, and interpretation of biological effects relative to plasma concentrations. The extremely short plasma half-life necessitates careful consideration of dose timing and frequency in experimental studies.

Research Applications

Reproductive Neuroendocrinology Research

Kisspeptin-10 serves as a fundamental research tool for investigating reproductive hormone regulation:

• GnRH Neuron Studies: Investigation of kisspeptin’s direct effects on GnRH neuron electrical activity, GnRH pulse generation, and GnRH secretion patterns
• Gonadotropin Secretion Research: Analysis of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) release following kisspeptin administration
• HPG Axis Regulation: Studies examining feedback mechanisms, sex steroid interactions, and reproductive axis integration
• GnRH Pulse Generator Investigation: Research on the hypothalamic mechanisms generating pulsatile GnRH/LH secretion patterns
• Neuroendocrine Integration: Examination of kisspeptin neuron connectivity with other hypothalamic regulatory systems
• Sex Differences in Regulation: Investigation of sexually dimorphic kisspeptin expression and function

Research protocols employ in vitro electrophysiology, calcium imaging in GnRH neurons, hypothalamic slice preparations, in vivo hormone sampling, and transgenic animal models to characterize kisspeptin-10’s effects on reproductive neuroendocrine function.

Puberty Onset and Development Studies

Kisspeptin’s critical role in puberty initiation makes it valuable for developmental research:

• Puberty Trigger Mechanisms: Investigation of the pubertal increase in kisspeptin signaling that initiates reproductive maturation
• Developmental Studies: Research on kisspeptin neuron development, KISS1R expression ontogeny, and reproductive axis maturation
• Metabolic Influences: Examination of how nutritional status, leptin, and metabolic signals influence pubertal kisspeptin activation
• Environmental Factors: Studies on endocrine disruptor effects, stress, and other factors modulating puberty timing
• Pathological Puberty Research: Investigation of precocious or delayed puberty mechanisms involving kisspeptin dysregulation
• Species Variation: Comparative studies of puberty mechanisms across different mammalian species

Experimental approaches include developmental hormone profiling, kisspeptin neuron imaging during pubertal transition, nutritional manipulation studies, and genetic models with altered kisspeptin signaling.

Fertility and Reproductive Physiology Research

Kisspeptin-10 research extends to fertility regulation and reproductive state investigations:

• Ovulatory Cycle Research: Studies examining kisspeptin’s role in generating the preovulatory LH surge
• Follicular Development Studies: Investigation of kisspeptin effects on ovarian follicle maturation and selection
• Seasonal Reproduction Research: Examination of photoperiod-driven kisspeptin changes controlling seasonal breeding
• Lactational Amenorrhea Studies: Research on kisspeptin suppression during lactation contributing to temporary infertility
• Reproductive Aging Research: Investigation of kisspeptin changes during reproductive senescence and menopause transition
• Male Fertility Studies: Examination of kisspeptin effects on testosterone production and spermatogenesis

Research protocols utilize reproductive cycle monitoring, ovarian stimulation studies, seasonal breeder models, lactation studies, and aging models to characterize kisspeptin’s roles in fertility regulation.

Metabolic-Reproductive Interface Research

Growing research examines kisspeptin as a link between metabolic status and reproductive function:

• Energy Balance Studies: Investigation of how negative energy balance suppresses kisspeptin and reproduction
• Leptin Signaling Research: Analysis of leptin’s effects on kisspeptin neurons mediating metabolic reproductive integration
• Obesity Effects: Studies examining altered kisspeptin signaling in obesity affecting reproductive function
• Diabetes Research: Investigation of metabolic disease effects on kisspeptin and reproductive outcomes
• Adipokine Interactions: Research on adiponectin, ghrelin, and other metabolic signals modulating kisspeptin
• Exercise Effects: Examination of exercise-induced reproductive suppression involving kisspeptin modulation

Experimental approaches include metabolic manipulation studies, leptin administration protocols, diet-induced obesity models, and comprehensive metabolic-reproductive phenotyping.

Neuroendocrine Pathway Investigation

Kisspeptin-10 serves as a tool for broader neuroendocrine research:

• Neuronal Circuitry Studies: Investigation of kisspeptin neuron connectivity with other hypothalamic populations
• Neurotransmitter Interactions: Research on GABA, glutamate, dopamine, and other transmitter interactions with kisspeptin
• Neuropeptide Networks: Examination of neurokinin B, dynorphin, and other neuropeptides co-expressed with kisspeptin
• Stress-Reproduction Interface: Studies on stress hormone effects on kisspeptin neurons mediating reproductive suppression
• Circadian Influences: Research on circadian clock interactions with kisspeptin regulating reproductive timing
• Optogenetic Studies: Investigation using kisspeptin neuron stimulation to dissect reproductive control mechanisms

Laboratory protocols employ tract-tracing, immunohistochemistry, in situ hybridization, electrophysiology, optogenetics, and chemogenetics to map kisspeptin neuron function within broader neural networks.

Peripheral KISS1R Research

Beyond hypothalamic functions, research investigates peripheral kisspeptin effects:

• Gonadal Research: Direct effects of kisspeptin on ovarian and testicular steroidogenesis
• Placental Studies: Investigation of placental kisspeptin production and potential autocrine/paracrine functions
• Metabolic Tissue Research: Effects on pancreatic beta cells, adipocytes, and metabolic regulation
• Vascular Studies: Kisspeptin effects on endothelial function and vascular tone
• Cancer Research: Investigation of KISS1 as metastasis suppressor gene and kisspeptin effects on tumor biology
• Immune Function: Emerging research on kisspeptin effects on immune cell function

These peripheral research applications employ cell culture models, isolated tissue preparations, and in vivo organ-specific studies to characterize extraneural kisspeptin functions.

Laboratory Handling and Storage Protocols

Lyophilized Powder Storage:

• Store at -20°C to -80°C in original sealed vial
• Protect from light exposure to prevent oxidation
• Desiccated storage environment critical to prevent moisture absorption
• Stability data available for 12+ months at -20°C when properly stored
• Avoid repeated temperature cycling of lyophilized material

Reconstitution Guidelines:

• Reconstitute with sterile water, bacteriostatic water (0.9% benzyl alcohol), or appropriate buffer
• Add solvent slowly down vial side to minimize foaming and peptide denaturation
• Gentle swirling motion recommended (avoid vigorous shaking that can damage peptide bonds)
• Allow complete dissolution before use (typically 2-3 minutes)
• Final pH should be 6.5-7.5 for optimal stability and biological activity
• Consider 0.1% BSA addition as carrier protein to prevent adsorption losses

Reconstituted Solution Storage:

• Short-term storage: 4°C for up to 5-7 days (bacteriostatic water provides antimicrobial protection)
• Long-term storage: -20°C in single-use aliquots to avoid freeze-thaw cycles
• Aliquot into appropriate volumes for individual experiments
• Avoid repeated freeze-thaw cycles (maximum 2-3 cycles; each cycle may reduce activity 10-20%)
• For extended studies, prepare fresh solution or use frozen aliquots

Stability Considerations:

• Peptide bonds susceptible to hydrolysis, especially at extreme pH
• Oxidation can occur at methionine, tryptophan, and tyrosine residues
• Light exposure may promote photochemical degradation
• Repeated freeze-thaw can cause aggregation and precipitation
• Dilute solutions more susceptible to degradation and adsorption losses
• Consider BSA or other carrier proteins in working solutions

Quality Assurance and Analytical Testing

Each kisspeptin-10 batch undergoes comprehensive analytical characterization:

Purity Analysis:

• High-Performance Liquid Chromatography (HPLC): ≥98% purity
• Analytical method: Reversed-phase HPLC with UV detection at 220nm and 280nm
• C18 column with acetonitrile-water gradient containing 0.1% TFA
• Multiple peak integration ensuring accurate purity determination
• Related substance analysis identifying potential impurities

Structural Verification:

• Electrospray Ionization Mass Spectrometry (ESI-MS): Confirms molecular weight 1,302.5 Da
• Multiple charge state analysis for accurate mass determination
• MALDI-TOF MS as orthogonal confirmation technique
• Amino acid analysis: Verifies sequence composition and amidation
• Peptide content determination: Quantifies actual peptide by weight (typically ≥80%)

Contaminant Testing:

• Bacterial endotoxin: <5 EU/mg via Limulus Amebocyte Lysate (LAL) method
• Heavy metals: Below detection limits per USP standards
• Residual solvents: TFA and acetonitrile within ICH guidelines
• Water content: Karl Fischer titration (<8% for lyophilized material)
• Bioburden testing for manufacturing quality control

Functional Testing:

• Receptor binding assay confirming KISS1R affinity
• Calcium mobilization assay verifying functional activity
• Comparison to reference standard maintaining consistency
• Biological activity typically >90% of theoretical based on purity

Documentation:

• Certificate of Analysis (COA) provided with each batch
• Includes chromatograms, mass spectra, and analytical data
• Third-party analytical verification available upon request
• Stability data documented for recommended storage conditions
• Batch-specific QC results traceable by lot number
• Regulatory compliance documentation for research applications

Research Considerations

Experimental Design Factors:

Researchers should consider several factors when designing kisspeptin-10 experiments:

1. Dose Selection: Published research reports effective concentrations ranging from picomolar to micromolar depending on application. In vitro receptor binding studies may use 1-100 nM. In vivo studies in rodents typically employ 1-100 nmol doses for central administration or 0.1-10 nmol/kg for peripheral administration. Dose-response characterization recommended for new applications.

2. Route of Administration: Multiple routes investigated in preclinical research:

• Intravenous: Direct systemic delivery with 100% bioavailability
• Subcutaneous: Convenient peripheral administration with rapid absorption
• Intracerebroventricular (ICV): Direct CNS delivery bypassing BBB limitations
• Intranasal: Investigated for direct brain delivery via olfactory pathways
• Route selection should align with research questions (central vs. peripheral effects)

3. Temporal Considerations: Kisspeptin-10’s extremely short half-life (2-5 minutes) contrasts with prolonged biological effects (hours):

• Single bolus injection produces acute stimulation
• Multiple injections or continuous infusion for sustained effects
• Timing of measurements critical relative to administration
• Pulsatile vs. continuous delivery produces different outcomes
• Consider circadian time of administration affecting responses

4. Model Selection: Choose appropriate systems based on research questions:

• In vitro: KISS1R-expressing cell lines, primary GnRH neurons, hypothalamic slices
• Ex vivo: Hypothalamic explants, pituitary cultures, gonadal tissue preparations
• In vivo: Species selection (mouse, rat, sheep, non-human primate models)
• Genetic models: KISS1R knockout, kisspeptin neuron-specific manipulations

5. Physiological State: Kisspeptin responses vary with reproductive state:

• Sex differences in kisspeptin sensitivity and expression
• Estrous/menstrual cycle stage affects responses
• Prepubertal vs. adult differences
• Metabolic state influences (fed vs. fasted, lean vs. obese)
• Seasonal state in photoperiodic species

6. Control Groups: Essential controls include:

• Vehicle-treated controls (saline or reconstitution buffer)
• Time-matched controls for temporal changes
• KISS1R antagonist co-administration to confirm receptor-mediated effects
• GnRH antagonist to distinguish GnRH-dependent vs. independent effects
• Positive controls with known active compounds

Mechanism Investigation:

Kisspeptin-10’s mechanisms involve multiple pathways and considerations:

• Receptor Pharmacology: KISS1R-mediated signaling well characterized, but potential additional targets investigated
• Neural Mechanisms: Direct effects on GnRH neurons vs. indirect through interneurons
• Downstream Cascades: GnRH → LH/FSH → gonadal steroids creates multilevel responses
• Feedback Interactions: Steroid feedback on kisspeptin neurons creates dynamic regulation
• Non-Reproductive Effects: Emerging peripheral functions require careful interpretation
• Species Differences: Significant variation in kisspeptin biology across species

Comprehensive mechanism investigation requires multi-level approaches examining receptor binding, cellular signaling, neuron activity, hormone secretion, and physiological outcomes.

Compliance and Safety Information

Regulatory Status:
Kisspeptin-10 is provided as a research chemical for in-vitro laboratory studies and preclinical research only. This product has not been approved by the FDA for human therapeutic use, diagnostic applications, dietary supplementation, or medical applications. Clinical research requires appropriate regulatory approvals (IND) and institutional review board oversight.

Intended Use:

• In-vitro cell culture and receptor binding studies
• In-vivo preclinical research in approved animal models
• Laboratory investigation of reproductive and neuroendocrine mechanisms
• Academic and institutional research applications
• Pharmaceutical research and drug discovery programs

NOT Intended For:

• Human consumption or administration outside approved clinical trials
• Therapeutic treatment or diagnosis
• Dietary supplementation or performance enhancement
• Veterinary therapeutic applications without appropriate oversight
• Any unregulated human use

Safety Protocols:
Researchers should follow standard laboratory safety practices when handling kisspeptin-10:

• Use appropriate personal protective equipment (lab coat, gloves, safety glasses)
• Handle in well-ventilated areas or fume hood
• Follow institutional biosafety guidelines and chemical hygiene plan
• Dispose of waste according to local regulations for biological/chemical waste
• Wash thoroughly after handling
• Consult Safety Data Sheet (SDS) for additional safety information
• Follow institutional animal care protocols for in vivo studies (IACUC approval required)

Preclinical Safety Observations:
Research in animal models has generally shown kisspeptin-10 to be well-tolerated at physiological doses. Supraphysiological doses may cause receptor desensitization or non-physiological effects. Long-term or repeated administration effects should be carefully monitored in research protocols.

—