Mk-677 12.5mg
MK-677 (Ibutamoren) is an orally active, non-peptidic growth hormone secretagogue that selectively binds and activates the ghrelin receptor (GHS-R1a) to stimulate endogenous growth hormone and IGF-1 secretion. A 12.5mg reference standard provides laboratory researchers with a precise, standardized mass unit for conducting in vitro receptor binding assays, enzyme kinetics, and preclinical somatotropic axis experiments. All materials supplied by PX1 Research are strictly intended for laboratory research use only.
Quick answer
MK-677 (Ibutamoren) is an orally active, non-peptidic growth hormone secretagogue that selectively binds and activates the ghrelin receptor (GHS-R1a) to stimulate endogenous growth hormone and IGF-1 secretion. A 12.5mg reference standard provides laboratory researchers with a precise, standardized mass unit for conducting in vitro receptor binding assays, enzyme kinetics, and preclinical somatotropic axis experiments. All materials supplied by PX1 Research are strictly intended for laboratory research use only.
Key takeaways
- MK-677, chemically identified as Ibutamoren mesylate (CAS 159752-10-0), represents a unique class of non-peptidic growth hormone secretagogues engineered to mimic the action of endogenous ghrelin.
- The primary mechanism of action for MK-677 centers on its high-affinity agonism of the Growth Hormone Secretagogue Receptor type 1a (GHS-R1a), a G-protein coupled receptor (GPCR) predominantly expressed in the anterior pituitary gland and hypothalamic nuclei.
- Following GHS-R1a activation and the resulting release of growth hormone into systemic circulation, GH binds to transmembrane growth hormone receptors (GHR) located on hepatic parenchymal cells.
- In rodent models of catabolism, researchers have utilized MK-677 to evaluate its capacity to mitigate diet-induced or surgical nitrogen loss.
Defining MK-677 12.5mg in Preclinical Research Contexts
MK-677, chemically identified as Ibutamoren mesylate (CAS 159752-10-0), represents a unique class of non-peptidic growth hormone secretagogues engineered to mimic the action of endogenous ghrelin. Unlike traditional peptide ligands that require parenteral administration due to rapid enzymatic degradation in plasma, MK-677 exhibits structural resistance to peptidases, enabling high oral bioavailability in animal models. The 12.5mg analytical unit provides researchers with a fixed, reproducible reference quantity for preparing cell culture media, working solution aliquots, and standardized assay protocols.
In experimental biology, establishing precise concentration gradients is vital for assessing receptor affinity, downstream signal transduction, and transcription factor activation. Utilizing a 12.5mg standardized lot allows laboratory investigators to eliminate baseline gravimetric variances across multi-plate assays, ensuring high inter-assay reproducibility when analyzing the somatotropic cascade in cell culture and animal tissue models. Researchers looking to integrate verified reference standards into their experimental designs can examine high-purity batch documentation within the PX1 Research catalog.
Molecular Mechanism: Selective GHS-R1a Agonism
The primary mechanism of action for MK-677 centers on its high-affinity agonism of the Growth Hormone Secretagogue Receptor type 1a (GHS-R1a), a G-protein coupled receptor (GPCR) predominantly expressed in the anterior pituitary gland and hypothalamic nuclei. Binding of MK-677 to GHS-R1a triggers a conformational change that activates the Gαq/11 signaling pathway. This cascade stimulates phospholipase C (PLC), generating inositol trisphosphate (IP3) and diacylglycerol (DAG).
Subsequent binding of IP3 to ligand-gated calcium channels on the endoplasmic reticulum induces a rapid intracellular calcium release into the cytosol. This intracellular calcium surge, alongside protein kinase C (PKC) activation, drives the exocytosis of pre-stored growth hormone granules from pituitary somatotropes. Furthermore, in vitro studies demonstrate that GHS-R1a activation by MK-677 antagonizes somatostatin receptor signaling, effectively lifting the tonic inhibition normally exerted by somatostatin on GH secretion. For a comprehensive comparison of secretagogue signaling pathways, consult our technical resource on growth hormone secretagogue mechanisms.
Downstream Endocrine Signaling and IGF-1 Modulation
Following GHS-R1a activation and the resulting release of growth hormone into systemic circulation, GH binds to transmembrane growth hormone receptors (GHR) located on hepatic parenchymal cells. This binding initiates receptor dimerization and activates the JAK2/STAT5b signal transduction pathway, driving the transcription and synthesis of Insulin-like Growth Factor 1 (IGF-1) and its primary serum carrier protein, Insulin-like Growth Factor Binding Protein 3 (IGFBP-3).
Preclinical studies show that continuous or intermittent exposure to MK-677 leads to sustained elevations in serum IGF-1 concentrations over extended periods. Unlike exogenous growth hormone administration, which can induce severe feedback inhibition of endogenous pituitary output, MK-677 preserves the natural pulsatile nature of GH secretion in animal models. This physiological preservation prevents complete down-regulation of the hypothalamic-pituitary axis while steadily enhancing systemic markers of somatotropic activity. Research groups examining downstream signaling pathways can review additional data in our guide to IGF-1 axis signaling.
Preclinical Literature Review: Metabolic and Nitrogen Balance Findings
In rodent models of catabolism, researchers have utilized MK-677 to evaluate its capacity to mitigate diet-induced or surgical nitrogen loss. Preclinical data indicate that administration of MK-677 significantly improves short-term and long-term nitrogen balance, facilitating nitrogen retention through enhanced amino acid transport and protein synthesis in skeletal muscle tissue. This nitrogen-sparing effect is primarily mediated through the combined anabolic actions of elevated GH and hepatic IGF-1.
Additionally, investigation into musculoskeletal biology demonstrates that prolonged exposure to GHS-R1a agonists enhances markers of bone turnover in preclinical models. In vitro osteoblast culture assays show elevated secretion of pro-collagen type I N-terminal propeptide (PINP) and osteocalcin, indicating active bone matrix deposition. Animal studies examining body composition changes report increased lean body mass accretion accompanied by shifts in substrate oxidation, favoring lipid mobilization during prolonged metabolic assays published across the PX1 Research library.
Comparative Analysis: MK-677 vs. Injectable Secretagogue Peptides
When evaluating secretagogue candidates in comparative laboratory models, researchers often contrast MK-677 with peptide-based GHS-R1a agonists such as Ipamorelin and GHRP-6, as well as GHRH analogues like CJC-1295 DAC, Sermorelin, and Tesamorelin. While GHRH analogues signal via the growth hormone-releasing hormone receptor to amplify natural GH pulses, MK-677 operates through ghrelin receptor activation with an extended biological half-life (~24 hours in preclinical systems), eliminating the need for frequent peptide reconstitution required by short-lived injectable agents.
Furthermore, while short-chain peptide agonists like Ipamorelin exhibit high selectivity with minimal impact on secondary pituitary hormones, MK-677 provides a sustained, long-acting profile suitable for chronic exposure models. Researchers selecting reagents for comparative studies must evaluate receptor specificity, pharmacokinetic half-life, and non-target hormone elevation (such as transient increases in cortisol or prolactin observed in early-phase animal trials) when establishing experimental controls.
Laboratory Handling, Solubilization, and Storage Protocols
MK-677 mesylate is supplied as a high-purity crystalline solid that requires appropriate lab safety measures and precise handling procedures. For quantitative analytical applications, the compound should be solubilized in organic solvents such as dimethyl sulfoxide (DMSO) or ethanol, in which it exhibits high solubility (>20 mg/mL). Aqueous buffers may be utilized following initial stock preparation in DMSO, provided the final organic solvent concentration remains compatible with downstream cellular assays.
Stock solutions should be prepared under sterile conditions using analytical-grade reagents. To preserve chemical integrity and prevent oxidative or hydrolytic degradation, dissolved stock aliquots must be stored at -20°C or -80°C in airtight, light-shielded containers. Lyophilized or solid reference powder should be stored in a dry, cool environment (2°C to 8°C or -20°C for long-term storage) away from direct light exposure. Repeated freeze-thaw cycles of liquid working stocks must be strictly avoided to maintain consistent molar concentrations during extended experimental series.
Quality Verification Framework: HPLC, Mass Spectrometry, and Endotoxin Limits
To ensure high experimental reproducibility, research materials must adhere to strict analytical purity standards. PX1 Research implements a rigorous quality assurance protocol for every lot of MK-677 12.5mg. Purity validation relies on Reverse-Phase High-Performance Liquid Chromatography (RP-HPLC), coupled with ultraviolet spectrophotometry to verify that chemical purity equals or exceeds 98.0%. Single-peak chromatographic resolution ensures the total absence of synthesis side-products or unreacted intermediates.
Molecular identity is verified through Electrospray Ionization Mass Spectrometry (ESI-MS), confirming the precise molecular weight (628.77 g/mol for MK-677 base, adjusted for mesylate salt stoichiometry). In addition to purity and structural confirmation, all lots undergo quantitative Limulus Amebocyte Lysate (LAL) testing to certify endotoxin levels fall below strict laboratory thresholds (<0.01 EU/mg). High-throughput laboratories seeking verified reference standards for scale applications can explore options for bulk lab purchasing.
Research Considerations and Experimental Controls in Secretagogue Assays
When designing in vitro or animal cell models incorporating MK-677 12.5mg, establishing appropriate negative and positive control parameters is essential. Because GHS-R1a receptors undergo receptor internalization and desensitization upon continuous high-concentration exposure, pulse-dosing or wash-out protocols are frequently employed in cell culture experiments to model endogenous biological rhythmicity.
Investigators must also account for downstream secondary messenger interactions. In somatotrope and hypothalamic explant models, baseline levels of extracellular calcium, serum-free media conditions, and ambient glucose concentrations can significantly alter the magnitude of GH release induced by MK-677. Maintaining uniform control conditions across experimental blocks is mandatory for isolating the specific biological actions of GHS-R1a agonism from environmental confounders.
Sourcing High-Purity MK-677 12.5mg Reference Compounds
Reliable experimental conclusions require reference compounds synthesized under stringent quality control. Substandard or unverified reagents introduce structural impurities, lot-to-lot variance, and unknown endotoxin contamination that jeopardize experimental integrity and invalidate research conclusions. PX1 Research compounds are manufactured in USA-based, GMP-compliant facilities and tested by independent, ISO 17025 accredited laboratories.
Every unit of MK-677 12.5mg supplied by PX1 Research is backed by a lot-specific Certificate of Analysis (COA) detailing full HPLC chromatograms, mass spectra, and certified endotoxin assay results. By standardizing reagent quality, PX1 Research empowers institutional and independent investigators to execute precise, highly reproducible research within the preclinical biological sciences.
Frequently Asked Questions
What is MK-677 12.5mg used for in laboratory research?
MK-677 12.5mg is used as a standardized analytical reference material for studying GHS-R1a receptor kinetics, growth hormone and IGF-1 signaling cascades, nitrogen retention mechanisms, and tissue metabolism in preclinical and in vitro laboratory models.
How does MK-677 differ from peptide GH secretagogues like Ipamorelin?
MK-677 is a non-peptidic, orally bioavailable compound with an extended biological half-life (~24 hours), whereas peptide secretagogues like Ipamorelin or CJC-1295 are amino acid chains requiring reconstituted liquid preparation and exhibit much shorter biological half-lives.
What solvents are recommended for dissolving MK-677 reference powder?
MK-677 mesylate readily dissolves in dimethyl sulfoxide (DMSO) or ethanol at concentrations exceeding 20 mg/mL. Once solubilized in organic solvent, working solutions can be diluted into cell culture media or aqueous buffer systems.
How is the purity of PX1 Research MK-677 12.5mg validated?
Every lot of MK-677 is tested via RP-HPLC to verify ≥98% chemical purity, ESI-Mass Spectrometry for structural identity verification, and LAL assays to ensure endotoxin limits remain below <0.01 EU/mg.
What are the recommended storage conditions for MK-677 12.5mg?
Dry, solid reference powder should be stored at 2°C to 8°C for short term or -20°C for long-term storage, protected from light and moisture. Solubilized stock aliquots should be frozen at -80°C to prevent hydrolysis.
Does MK-677 trigger cortisol or prolactin release in preclinical models?
Preclinical data show MK-677 selectively targets GHS-R1a. While mild, transient elevations in cortisol and prolactin have been observed in early experimental exposure, its affinity for somatotropic release is significantly higher than for stress axis activation.
Why is lot-specific COA verification critical for MK-677 research?
Lot-specific COAs confirm chemical purity, mass verification, and freedom from endotoxins. Without COA verification, uncharacterized impurities can alter cellular assays, induce non-specific cytotoxicity, or invalidate published experimental results.
Can institutions purchase bulk quantities of MK-677 12.5mg?
Yes, PX1 Research supports institutional research facilities and academic laboratories with bulk supply, custom unit formatting, and lot reservation services through our dedicated wholesale program.
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All products are sold strictly for laboratory and research use only. Not for human or veterinary use, diagnosis, treatment or consumption. Statements have not been evaluated by the FDA.