GH / IGF Research

MK-677 (10 mg)

Non-Peptide Ghrelin Receptor Agonist / Growth Hormone Secretagogue (GHSR-1a)

MK-677 (also known as Ibutamoren) is a potent, orally active, non-peptide agonist of the Growth Hormone Secretagogue Receptor (GHSR-1a) — the same receptor activated by endogenous ghrelin and synthetic GHRP peptides (e.g., GHRP-2, GHRP-6, Hexarelin).

Unlike peptide GH secretagogues, MK-677 is:

• Orally bioavailable

• Long-acting (half-life ~24 hours)

• Capable of producing sustained increases in GH, IGF-1, and IGFBP-3

Because of these properties, MK-677 is widely used for research in:

• GH/IGF-1 axis physiology

• Muscle wasting & sarcopenia models

• Bone density & fracture healing

• Sleep architecture & circadian GH release

• Metabolic and appetite-regulation studies

• Aging, regeneration, and neuroendocrine decline

MK-677 (10 mg) is provided strictly for laboratory research and not for human consumption.

Specifications

Synonyms: MK-677, Ibutamoren, L-163,191, Oratrope
Class: Non-peptide GHSR-1a agonist / GH secretagogue
Molecular Formula: C₂₇H₃₆N₄O₅S
Molecular Weight: ~528.7 g/mol
Presentation: 10 mg research-grade compound (≥98% purity)

Mechanism of Action & Endocrine Signaling

MK-677 binds selectively to GHSR-1a receptors, activating the same intracellular signaling cascade triggered by ghrelin and peptide GHRPs.

1. GHSR-1a activation

Binding stimulates:

• ↑ IP₃ and intracellular Ca²⁺

• ↑ PKC activation

• ↑ GH release from pituitary somatotrophs

• Inhibition of somatostatin (GH antagonist)

This produces a robust increase in:

• Growth hormone (GH)

• Insulin-like growth factor-1 (IGF-1)

• IGF binding protein-3 (IGFBP-3)

2. Long-acting GH stimulation

Unlike peptides that produce sharp pulses, MK-677 maintains:

• Sustained GH elevation for ~24 hours

• Physiologic GH pulsatility (does not override rhythm entirely)

3. Ghrelin-mimetic actions

MK-677 acts on brain ghrelin receptors involved in:

• Appetite regulation

• Sleep cycle modulation

• Energy balance

• Growth hormone feedback loops

GH/IGF-1 Axis Research Effects

1. Muscle growth & anti-catabolic models

Experimental findings show:

• Increased lean mass in GH-deficient models

• Prevention of muscle wasting

• Enhanced protein synthesis

• Improved recovery from tissue damage

MK-677 is a major research tool in sarcopenia, cachexia, and aging muscle studies.

2. Bone density & fracture repair

IGF-1 is essential for bone remodeling. MK-677 research demonstrates:

• Improved bone mineral density (BMD)

• Accelerated fracture healing

• Increased osteoblast activity

• Reduced bone turnover markers associated with aging

3. Sleep architecture and neuroendocrine function

Because GH release is tied to deep sleep, MK-677 is used in studies investigating:

• Increased REM and slow-wave sleep

• Enhanced nighttime GH pulses

• Age-related declines in endogenous GH secretion

4. Metabolic and endocrine modulation

MK-677 research shows:

• Improved nitrogen retention

• Reduced inflammatory markers

• Increased basal metabolic rate

• Enhanced fatty-acid oxidation

Appetite & Metabolic Regulation Research

As a ghrelin mimetic, MK-677 activates hypothalamic pathways involved in:

• Appetite stimulation

• Energy intake and expenditure

• Glucose homeostasis

• Insulin sensitivity (effects vary by model)

It is often used to study hunger signaling, energy balance, and endocrine obesity models.

Neuroprotective & Cognitive Research

IGF-1 is essential for brain health; MK-677–induced IGF-1 elevation supports research in:

• Cognitive decline

• Neurodegenerative models

• Motor learning

• Synaptic plasticity

• Neurogenesis

MK-677 is also used to investigate neuroendocrine aging and pituitary feedback loops.

Comparison to Peptide GHRPs

Safety, Limitations & Regulatory Notes

• MK-677 is not FDA- or EMA-approved for any therapeutic use.

• Research models report transient increases in appetite, water retention, and fasting glucose—important for study design.

• Long-term IGF-1 elevation should be monitored in experimental settings.

• Research-grade MK-677 is not for human or veterinary use and should not be used for bodybuilding, performance, or weight manipulation.

Research Use Only – Important Notice

This MK-677 (10 mg) material is supplied strictly for laboratory research.

• Not for human consumption

• Not for therapeutic, cosmetic, or diagnostic purposes

• For in vitro and controlled animal model experimentation only

• Descriptions summarize findings from endocrine, metabolic, and neurobiological literature

• Not to be interpreted as medical or dosing guidance

References (peer-reviewed, non-Wikipedia)

1. Nass R et al. The GH-releasing effect of MK-677 in healthy adults. J Clin Endocrinol Metab.
   https://pubmed.ncbi.nlm.nih.gov/9467531/

Murphy MG et al. MK-677 increases GH, IGF-1 and fat-free mass. J Clin Endocrinol Metab.
https://pubmed.ncbi.nlm.nih.gov/9079585/

Chapman IM et al. MK-677 improves sleep and GH secretion in elderly subjects. J Clin Endocrinol Metab.
https://pubmed.ncbi.nlm.nih.gov/9645672/

Svensson J et al. Metabolic and body composition effects of MK-677. J Clin Endocrinol Metab.
https://pubmed.ncbi.nlm.nih.gov/10022410/

Smith RG et al. GHSR-1a receptor signaling and ghrelin mimetics. Endocr Rev.
https://pubmed.ncbi.nlm.nih.gov/11588148/