Growth Hormone Secretagogue
Also known as: GHS, Ghrelin Mimetic, GH Secretagogue
Growth Hormone Secretagogue refers to a class of compounds that stimulate the pituitary gland to release growth hormone by activating the ghrelin receptor (GHS-R1a). Unlike GHRH analogs, GHS compounds mimic the hunger hormone ghrelin and include both peptides like ipamorelin and non-peptide molecules like MK-677.
Last updated: January 28, 2026
How Growth Hormone Secretagogues Work
Growth hormone secretagogues operate through the ghrelin receptor pathway:
- Receptor binding - GHS binds to GHS-R1a (ghrelin receptor) on pituitary somatotrophs
- Calcium signaling - Triggers intracellular calcium release
- GH release - Stimulates growth hormone secretion from stored vesicles
- Amplification - Enhances the amplitude of natural GH pulses
The GHS-R1a receptor is distinct from the GHRH receptor, allowing GHS compounds to work through a complementary pathway.
Relevance to Peptides
Growth hormone secretagogues represent a major class of research peptides and compounds. They are studied for their ability to increase growth hormone levels without direct GH administration.
Peptide GHS Compounds
- Ipamorelin - Selective pentapeptide GHS with minimal side effects
- GHRP-2 - Potent hexapeptide with some cortisol effects
- GHRP-6 - First-generation GHS with appetite stimulation
- Hexarelin - Strong GHS with cardiac effects studied
Non-Peptide GHS Compounds
- MK-677 (Ibutamoren) - Orally active non-peptide GHS
- Provides sustained GH elevation over 24 hours
- Studied for muscle wasting and osteoporosis research
GHS vs GHRH Analogs
| Feature | GHS | GHRH Analogs |
|---|---|---|
| Receptor | GHS-R1a (ghrelin) | GHRH receptor |
| Action | Amplifies GH pulses | Initiates GH pulses |
| Oral availability | Some (MK-677) | None currently |
| Appetite effects | May increase hunger | Minimal |
| Synergy | Works with GHRH | Works with GHS |
Research Applications
GHS compounds are investigated for:
- Sarcopenia - Age-related muscle loss
- Growth hormone deficiency - Alternative to direct GH
- Cachexia - Wasting conditions
- Sleep quality - GH release during deep sleep
- Bone density - IGF-1 effects on bone metabolism
Frequently Asked Questions
What makes MK-677 different from peptide GHS?
MK-677 is a non-peptide growth hormone secretagogue that can be taken orally. Peptide GHS compounds like ipamorelin must be injected because they would be degraded in the digestive system. MK-677 also has a much longer half-life, providing sustained GH elevation.
Do GHS compounds cause the same side effects as growth hormone?
Not exactly. GHS compounds stimulate natural GH release rather than providing exogenous GH. This typically preserves pulsatile release patterns. However, sustained GHS use can still increase IGF-1 and cause water retention, joint discomfort, and other GH-related effects.
Why combine GHS with GHRH peptides?
GHS and GHRH work through different receptors and mechanisms. GHRH initiates GH pulses while GHS amplifies them. Combining both may produce synergistic GH release greater than either alone, which is why research protocols often study combinations like CJC-1295 with ipamorelin.
Related Peptides
Related Terms
Disclaimer: This glossary entry is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider for medical questions.