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The phrase "growth hormone secretagogue" gets used as though it describes a single class of molecule. It does not. It describes a behaviour characterised at receptors on the somatotropic axis - one that two completely separate receptor families happen to share. Lump sermorelin and ipamorelin into one bucket and you have grouped two compounds that bind different receptors, on different chromosomes, with different signalling. This page sorts the catalogue's growth-hormone-axis peptides by the only thing that actually organises them: which receptor they engage. Everything below is receptor pharmacology and chemistry. Kovalabs supplies these compounds strictly as research reagents, and nothing here describes any human or animal use, dose, route, schedule or outcome.
In pharmacology, a secretagogue is simply a substance characterised in the literature by its role in the secretion of something. The "growth hormone secretagogue" label is a functional grouping, not a structural one: it collects peptides that have been studied for their interaction with receptors on the growth-hormone axis. The trap is treating the label as if it implied a shared mechanism. It does not. Two distinct receptors are involved, and a compound is defined by which one it binds, not by the umbrella term.
The cleaner way to read the field is to split it in two. On one side sit the GHRH analogues - peptides whose sequence is built from growth-hormone-releasing hormone, engaging the GHRH receptor (GHRHR). On the other sit the ghrelin-receptor agonists - peptides built to engage the growth-hormone-secretagogue receptor type 1a (GHS-R1a), the receptor that the stomach hormone ghrelin was later found to activate. These are receptor classes only.
The historical order is worth knowing because it explains the naming mess. The GHS-R1a receptor was cloned first, in 1996, as the target of synthetic small-molecule secretagogues - Howard AD et al. (Science, 1996; PMID 8688086), in the paper titled "A receptor in pituitary and hypothalamus that functions in growth hormone release", described that receptor. It was an orphan receptor with no known endogenous ligand until Kojima M et al. (Nature, 1999; PMID 10604470) identified ghrelin, an acylated peptide from stomach, as that ligand. So the synthetic agonists predated the discovery of what the receptor was actually for, which is why the "secretagogue receptor" name stuck even though "ghrelin receptor" describes the same protein.
The GHRH receptor is a different protein entirely - a separate G-protein-coupled receptor with its own gene, engaged by analogues of growth-hormone-releasing hormone rather than by ghrelin-mimetic peptides. Both receptors sit somewhere on the broader growth-hormone axis, but shared-axis membership is not shared pharmacology. A GHRH analogue and a GHS-R1a agonist are not interchangeable at the bench, do not cross-react at each other's receptor in any meaningful way, and belong in separate catalogue groupings.
| Compound | Receptor family | Target receptor (as characterised) | Example identifier |
|---|---|---|---|
| Sermorelin | GHRH analogue | GHRH receptor (GHRHR) | PubChem CID 16132413 |
| Tesamorelin | GHRH analogue | GHRH receptor (GHRHR) | PubChem CID 16137828 |
| CJC-1295 (no DAC) | GHRH analogue | GHRH receptor (GHRHR) | PubChem CID 91976842 (DAC record: 91971820) |
| Ipamorelin | GHS-R1a / ghrelin-receptor agonist | GHS receptor type 1a (GHS-R1a) | PubChem CID 9831659 |
| GHRP-6 | GHS-R1a / ghrelin-receptor agonist |
Within the GHRH-analogue family the compounds are best read as variations on a single backbone: growth-hormone-releasing hormone, of which the first 29 residues (GRF 1-29) carry the receptor-binding portion. The differences are molecular-engineering decisions, not differences in receptor target.
Sermorelin is GRF 1-29 itself - the truncated 29-residue fragment of human GHRH. PubChem resolves it to CID 16132413 with molecular formula C149H246N44O42S and an average molecular weight near 3358. It is the most direct fragment-of-the-native-hormone representative of the group.
Tesamorelin is a stabilised GHRH analogue: the GRF 1-44 sequence carrying an N-terminal modification that the literature describes as conferring resistance to enzymatic degradation. It is the largest molecule in the group, PubChem CID 16137828, formula C221H366N72O67S, with a molecular weight above 5000. Same receptor target, a different stabilisation strategy.
CJC-1295 is a GHRH analogue that exists in two forms which share a sequence but differ in one modification. The DAC (drug-affinity-complex) form carries a maleimido group designed in the literature to bind serum albumin; the no-DAC form omits it. The brief here concerns CJC-1295 (no DAC), the variant without the albumin-binding moiety, which PubChem indexes under CID 91976842 with formula C152H252N44O42 and a molecular weight near 3368; the separate DAC record (CID 91971820) carries the maleimido modification and a higher mass. Confirm the exact form and modification state against the supplied lot certificate of analysis, because the DAC and no-DAC records are easy to conflate on a data sheet that does not state which it describes. For a closer look at how a GHRH analogue is studied alongside a GHS-R1a agonist, see the CJC-1295 and ipamorelin research post.
The ghrelin-receptor agonists are not fragments of a hormone. They are synthetic peptides designed from the ground up to engage GHS-R1a, the Gq/11-coupled GPCR that Howard et al. cloned in 1996 and that ghrelin was later shown to activate. Within the family the differences are size and receptor selectivity, both characterised at the receptor level.
GHRP-6 is the prototypical member: a synthetic hexapeptide (His-D-Trp-Ala-Trp-D-Phe-Lys-NH2), PubChem CID 9919153, formula C46H56N12O6. It belongs to the first generation of growth-hormone-releasing peptides characterised before the receptor had been formally cloned, which is why much of the early secretagogue literature is built around it.
Ipamorelin is a later, smaller pentapeptide (Aib-His-D-2Nal-D-Phe-Lys-NH2), PubChem CID 9831659, formula C38H49N9O5, introduced by Raun K et al. (Eur J Endocrinol, 1998; PMID 9849822) and characterised in that report as a selective GHS-R1a agonist. The distinction the primary literature draws between these two is one of receptor selectivity profile, not of a downstream effect - which is a receptor-pharmacology property and the only basis on which the two are grouped together here.
A vial labelled GHRP-6 is not automatically a vial that contains GHRP-6, and the two GHS-R1a peptides differ by formula and mass that a certificate of analysis resolves cleanly: confirm identity and purity against the lot document rather than the label.
The chemistry of each compound is unambiguous: the formulae and PubChem records converge on single molecules, and the two-family receptor distinction is well established - GHRHR and GHS-R1a are separate, separately cloned proteins (Howard et al., 1996, PMID 8688086), and ghrelin is settled as the endogenous GHS-R1a ligand (Kojima et al., 1999, PMID 10604470). The middle ground is the foundational receptor and secretory characterisation, which rests heavily on in-vitro pituitary-cell work and preclinical animal pharmacology - a cultured pituitary cell shows the secretory machinery, not a human result. Human evidence across these compounds is the thinnest and most uneven part, and this page reports none of it as outcome. None of these is a licensed medicine, and none has been shown here to produce defined outcomes in humans. The receptor classification is the durable fact; the rest is open.
The compounds grouped on this page are supplied by Kovalabs as research reference materials intended solely for in-vitro and laboratory research by qualified professionals. They are for research use only and are not medicines, supplements or foods. They are not for human or veterinary use, not for diagnostic use, and not for any form of administration to humans or animals. Nothing here constitutes medical, therapeutic or dosing advice, and no clinical benefit, effect or outcome is stated or implied - the page describes receptor pharmacology and chemistry only. Purchasers are responsible for handling, storing and using the material in compliance with all applicable laws and institutional safety requirements. Please review the full terms at Research-use disclaimer before purchase.
It is a functional grouping for peptides characterised in the literature by their interaction with receptors on the growth-hormone axis. The term does not imply a single mechanism: two distinct receptor families fall under it - GHRH analogues that engage the GHRH receptor (GHRHR), and ghrelin-receptor agonists that engage the growth-hormone-secretagogue receptor type 1a (GHS-R1a). A compound is defined by which receptor it binds, not by the umbrella label. These are research reference materials only, not for human or veterinary use.
The first is the GHRH-receptor (GHRHR) family - GHRH analogues built from growth-hormone-releasing hormone, including sermorelin (the GRF 1-29 fragment), tesamorelin (a stabilised GHRH analogue) and CJC-1295 in its DAC and no-DAC forms. The second is the GHS-R1a / ghrelin-receptor family - synthetic agonists at the receptor ghrelin activates, including ipamorelin (a selective GHS-R1a pentapeptide) and GHRP-6. The GHS-R1a receptor was cloned in 1996 (PMID 8688086) and de-orphanised by the discovery of ghrelin in 1999 (PMID 10604470). The two families bind separate receptors and are not interchangeable.
No. They share membership of the broader growth-hormone axis but engage different receptors - GHRHR versus GHS-R1a - which are distinct G-protein-coupled proteins encoded by different genes. Shared-axis membership does not mean shared pharmacology, and the two classes do not meaningfully cross-react at each other's receptor. This is a receptor-target distinction only; no downstream physiological effect is asserted for either family on this page.
GHRH-analogue family (GHRHR): sermorelin, tesamorelin and CJC-1295 (no DAC). GHS-R1a / ghrelin-receptor family: ipamorelin and GHRP-6. Each links to its own research page, and each compound's identity should be confirmed against its lot certificate of analysis rather than the vial label - the verified PubChem records are CID 16132413 (sermorelin), CID 16137828 (tesamorelin), CID 91976842 (CJC-1295 no DAC), CID 9831659 (ipamorelin) and CID 9919153 (GHRP-6).
This page makes no safety, efficacy or approval claim of any kind. Kovalabs supplies these compounds strictly as research reference materials for laboratory investigation by qualified researchers. They are for research use only and are not for human or veterinary use. Full terms are at Research-use disclaimer.
Publication titles below are the original authors' own titles and are reproduced for citation; they are not statements or claims by Kovalabs.
| PubChem CID 9919153 |