Growth hormone secretagogues (GHS) are a class of compounds that stimulate the body’s own release of growth hormone from the anterior pituitary, rather than supplying growth hormone directly. They fall into two main mechanistic groups: growth hormone-releasing hormone (GHRH) analogues, which act on the GHRH receptor, and ghrelin receptor agonists (also called growth hormone-releasing peptides), which act on the growth hormone secretagogue receptor GHSR-1a. The two groups act through distinct but complementary pathways, which is why they are frequently combined in research. This guide explains what growth hormone secretagogues are, the two classes and how they differ, why they are often paired, and which compounds feature in laboratory research.
The two classes at a glance
| Property | GHRH analogues | Ghrelin receptor agonists |
|---|---|---|
| Receptor target | GHRH receptor | GHSR-1a (ghrelin receptor) |
| Primary signalling | Gαs → cAMP | Gαq → phospholipase C → IP₃ |
| Mimics | Growth hormone-releasing hormone | Ghrelin |
| Examples | Sermorelin, Tesamorelin, CJC-1295 | Ipamorelin, GHRP-2, GHRP-6, Hexarelin |
| Also called | GHRH agonists | Growth hormone-releasing peptides (GHRPs) |
What a secretagogue is
The word “secretagogue” simply means a substance that causes another substance to be secreted. A growth hormone secretagogue is therefore a compound that triggers the secretion of growth hormone. The defining feature of this class is the indirect mechanism: rather than introducing growth hormone from outside, a secretagogue stimulates the pituitary gland to release more of its own stored growth hormone.
This indirect approach is of interest in research because it works through the body’s existing regulatory machinery. Growth hormone release is normally controlled by a balance of stimulatory and inhibitory signals, and because secretagogues act on the upstream receptors that govern release, the resulting growth hormone output remains subject to some of the body’s own feedback regulation — including the natural pulsatile pattern in which growth hormone is normally secreted. This is a key conceptual distinction from administering growth hormone directly, and it is part of why secretagogues are studied as research tools for understanding the growth hormone axis.
Class 1: GHRH analogues
The first class mimics growth hormone-releasing hormone (GHRH), the hypothalamic hormone that signals the pituitary to release growth hormone.
Mechanism
GHRH analogues bind and activate the GHRH receptor on pituitary somatotroph cells. This receptor couples primarily to the Gαs–adenylyl cyclase–cAMP pathway, and its activation stimulates the synthesis and release of growth hormone. Because native GHRH is degraded within minutes by the enzyme dipeptidyl peptidase IV (DPP-IV), synthetic GHRH analogues are engineered for greater stability — typically through amino acid substitutions that resist DPP-IV cleavage.
Examples
Sermorelin is a GHRH analogue corresponding to the first 29 amino acids of GHRH. Tesamorelin is a stabilised GHRH analogue studied in clinical research. CJC-1295 is a modified GHRH(1-29) analogue available in two forms — with and without the Drug Affinity Complex (DAC) — that differ dramatically in half-life. For detail on the two CJC-1295 forms, see our guide on CJC-1295 DAC vs no DAC.
Class 2: ghrelin receptor agonists
The second class mimics ghrelin, the hormone that acts on a separate pituitary receptor to stimulate growth hormone release. These compounds are also called growth hormone-releasing peptides (GHRPs).
Mechanism
Ghrelin receptor agonists bind and activate the growth hormone secretagogue receptor GHSR-1a — the same receptor that endogenous ghrelin acts on. This receptor couples primarily to the Gαq–phospholipase C–IP₃ pathway, a different intracellular signalling route from the GHRH receptor. Activation stimulates growth hormone release through this independent pathway, and also influences the hypothalamic regulation of growth hormone secretion.
Examples and the selectivity question
This class includes GHRP-2, GHRP-6, Hexarelin and Ipamorelin. Published studies report differences in receptor selectivity and off-target endocrine signalling between these compounds. Ipamorelin has been characterised as a comparatively selective ghrelin-receptor agonist, with lower reported effects on cortisol and prolactin than several earlier secretagogues under experimental conditions.
Why the two classes are combined
The most common configuration in growth hormone secretagogue research is a combination of one GHRH analogue and one ghrelin receptor agonist. The rationale rests on the fact that the two classes act on different receptors through different signalling pathways that converge on the same output.
Because the GHRH receptor (Gαs–cAMP) and GHSR-1a (Gαq–phospholipase C) operate through independent intracellular routes, stimulating both simultaneously produces a greater effect on growth hormone release in published preclinical models than stimulating either alone. The two pathways are complementary rather than redundant, and their parallel activation is the basis for the synergy reported when the classes are paired.
The classic research pairing is CJC-1295 (no DAC) with Ipamorelin — a stable but short-acting GHRH analogue combined with a selective short-acting ghrelin agonist. Their compatible kinetics allow both to act within the same window and produce a single coordinated pulse of growth hormone release. For a full overview of this pairing, see our CJC-1295 & Ipamorelin research guide.
Why pulsatility matters
A recurring theme in growth hormone secretagogue research is the preservation of pulsatile release. Growth hormone is not normally secreted at a constant level — it is released in discrete pulses, with the largest typically occurring during slow-wave sleep. This pulsatile pattern is considered physiologically important, and continuous (non-pulsatile) stimulation of growth hormone pathways can lead to receptor desensitisation over time.
Because secretagogues act on the upstream receptors rather than supplying growth hormone directly, they can produce growth hormone release that retains a pulsatile character — particularly when short-acting compounds are used. This is one of the conceptual attractions of the secretagogue approach as a research tool, and a key reason short-acting compounds (like CJC-1295 no DAC and Ipamorelin) are favoured for research approximating physiological release dynamics.
Frequently asked questions
What is a growth hormone secretagogue?
A growth hormone secretagogue is a compound that stimulates the body’s own release of growth hormone from the pituitary, rather than supplying growth hormone directly. It acts on the upstream receptors that regulate growth hormone secretion — either the GHRH receptor or the ghrelin receptor (GHSR-1a).
What are the two main types?
GHRH analogues (which act on the GHRH receptor and mimic growth hormone-releasing hormone — e.g. Sermorelin, Tesamorelin, CJC-1295) and ghrelin receptor agonists, also called growth hormone-releasing peptides (which act on GHSR-1a and mimic ghrelin — e.g. Ipamorelin, GHRP-2, GHRP-6, Hexarelin).
Why are GHRH analogues and ghrelin agonists combined?
The two classes act on different receptors through different intracellular signalling pathways that converge on growth hormone release. Stimulating both simultaneously produces a greater effect in preclinical models than either alone, because the pathways are complementary. CJC-1295 (no DAC) with Ipamorelin is the classic research pairing.
Why is Ipamorelin preferred over GHRP-6 or GHRP-2?
Ipamorelin is more selective. It stimulates growth hormone release with minimal reported effect on cortisol and prolactin, whereas earlier ghrelin agonists like GHRP-6 and GHRP-2 produce more off-target activity (GHRP-6 is notably associated with strong appetite stimulation). This selectivity makes Ipamorelin the preferred ghrelin agonist in modern research blends.
How do secretagogues differ from growth hormone itself?
Growth hormone administration supplies the hormone directly. Secretagogues instead stimulate the pituitary to release its own growth hormone, which means the output remains partly subject to the body’s feedback regulation and can retain a pulsatile release pattern. This is a key conceptual distinction in research using these compounds.
Can growth hormone secretagogues be used in humans?
No. Trutide research products are supplied strictly for in vitro laboratory and scientific research. They are not for human or veterinary use, clinical use, self-administration, diagnosis, treatment or prevention of disease.
Further reading
Research use only. This article is provided for laboratory and scientific reference purposes. Trutide research products are supplied strictly for in vitro laboratory research and are not for human or veterinary use, clinical use, self-administration, diagnosis, treatment or prevention of disease.
References
- Raun K, Hansen BS, Johansen NL, et al. Ipamorelin, the first selective growth hormone secretagogue. European Journal of Endocrinology. 1998;139(5):552-561. doi:10.1530/eje.0.1390552
- Teichman SL, Neale A, Lawrence B, et al. Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults. The Journal of Clinical Endocrinology & Metabolism. 2006;91(3):799-805. doi:10.1210/jc.2005-1536
- Sinha DK, Balasubramanian A, Tatem AJ, et al. Beyond the androgen receptor: the role of growth hormone secretagogues in the modern management of body composition in hypogonadal males. Translational Andrology and Urology. 2020;9(Suppl 2):S149-S159. doi:10.21037/tau.2019.11.30
- Bowers CY. Growth hormone-releasing peptide (GHRP). Cellular and Molecular Life Sciences. 1998;54(12):1316-1329. doi:10.1007/s000180050257
- Kojima M, Hosoda H, Date Y, et al. Ghrelin is a growth-hormone-releasing acylated peptide from stomach. Nature. 1999;402(6762):656-660. doi:10.1038/45230
Last updated: 6 June 2026