In-vitro and preclinical literature on Sermorelin, Ipamorelin and Mod GRF 1-29: mechanisms, model systems and 15 PubMed-linked references.
✔ PubMed-linked citations ✔ In-vitro and preclinical only ✔ Research Use Only
Growth hormone secretagogues (GHS) are peptides studied for their interaction with the two receptor systems that regulate somatotroph GH release in preclinical models: the GHRH receptor (GHRH-R, a class B G protein-coupled receptor coupled to adenylate cyclase/cAMP) and the ghrelin receptor GHS-R1a (a class A GPCR coupled to Gq/phospholipase C and calcium signaling). The class is divided into GHRH analogs (GRF 1-29 fragments and their stabilized derivatives) and ghrelin-mimetic growth hormone-releasing peptides (GHRPs) such as ipamorelin. The foundational literature is largely in-vitro pharmacology (rat anterior pituitary membranes and dispersed pituitary cells, receptor cloning and transfected cell lines, plasma-enzyme stability assays) and animal models in rat and swine. Later clinical work exists for several compounds but is outside the scope of this research-use-only library, which focuses on mechanism, structure-activity relationships and model systems.
This page collects 20 peer-reviewed references across 4 compounds. Every citation links to its PubMed record so the primary source can be read in full. The selection is limited to in-vitro, ex-vivo and preclinical animal studies and mechanistic reviews; human clinical literature is deliberately excluded because Liv Pure products are supplied for laboratory research only.
Also known as: GRF(1-29)-NH2; hGRF(1-29)-NH2; GHRH(1-29) amide; human pancreatic GRF(1-29)
Molecular target or pathway: Pituitary GHRH receptor (GHRH-R), a class B G protein-coupled receptor; activation of adenylate cyclase and cAMP accumulation in somatotrophs
Origin: Synthetic 29-residue N-terminal fragment of endogenous human growth hormone-releasing hormone (GHRH 1-44), C-terminally amidated
Sermorelin is the 1-29 amidated fragment of human GHRH and has been used since the mid-1980s as the reference agonist in GHRH-receptor pharmacology. Rat anterior-pituitary membrane assays established that the 1-29 fragment retains full adenylate cyclase activation and were used to map which residues govern receptor recognition and activation. Plasma-enzymology studies showed rapid dipeptidyl peptidase IV cleavage at the 2-3 bond, which motivated the stabilized analogs elsewhere in this class. Most later sermorelin literature is clinical and is not included here; the references below are limited to receptor, structure-activity and stability work.
Liv Pure supplies Sermorelin as a lyophilized research reagent with a lot-specific certificate of analysis.
Selected references
Also known as: NNC 26-0161; Aib-His-D-2-Nal-D-Phe-Lys-NH2; pentapeptide growth hormone-releasing peptide (GHRP class)
Molecular target or pathway: Ghrelin receptor GHS-R1a (growth hormone secretagogue receptor), a class A G protein-coupled receptor; responses in pituitary cells blocked by GHRP-receptor antagonists
Origin: Synthetic pentapeptide derived from the GHRP-1 series by deletion of the central Ala-Trp dipeptide (Novo Nordisk)
Ipamorelin was described in 1998 as a GHRP-receptor agonist that released GH from primary rat pituitary cells with potency similar to GHRP-6 while, unlike GHRP-2 and GHRP-6, not increasing ACTH or cortisol in swine. It became a lead structure for medicinal-chemistry programs on smaller, orally available secretagogues. Later preclinical work has used it as a peripherally restricted ghrelin-receptor agonist in rat gastrointestinal motility and nociception models. Several human studies exist but are outside this library's scope.
Liv Pure supplies Ipamorelin as a lyophilized research reagent with a lot-specific certificate of analysis.
Selected references
Also known as: Modified GRF(1-29); [D-Ala2, Gln8, Ala15, Leu27]-hGRF(1-29)-NH2; tetrasubstituted GRF(1-29); CJC-1295 no DAC
Molecular target or pathway: Pituitary GHRH receptor (GHRH-R); adenylate cyclase/cAMP signaling in somatotrophs; designed for resistance to dipeptidyl peptidase IV and trypsin-like plasma cleavage
Origin: Synthetic analog of the GRF(1-29) fragment of human GHRH carrying four amino-acid substitutions; identical to the peptide backbone of CJC-1295 without the C-terminal maleimidopropionyl-lysine (DAC) group
Mod GRF 1-29 is the tetrasubstituted hGRF(1-29) backbone from which CJC-1295 was built. Its substitutions come directly from 1980s-1990s structure-activity work on rat pituitary systems: D-Ala2 blocks dipeptidyl peptidase IV cleavage at the 2-3 bond and behaved as a super-agonist in rat pituitary adenylate cyclase assays, Ala15 increased potency in the rat pituitary bioassay, and Gln8/Leu27 replace oxidation- and deamidation-prone residues. The analog itself has little dedicated primary literature; the references below cover the component substitutions and the DPP-IV stability data that define it.
Liv Pure supplies Mod GRF 1-29 (CJC-1295 without DAC) as a lyophilized research reagent with a lot-specific certificate of analysis.
Selected references
GHRH-derived peptides (sermorelin, Mod GRF 1-29, CJC-1295) are characterized against the pituitary GHRH receptor, a class B GPCR that increases cAMP through adenylate cyclase (Mayo 1992; Robberecht 1985). Ghrelin-mimetic peptides such as ipamorelin are characterized against GHS-R1a, the receptor cloned by Howard et al. (1996), and their responses in pituitary-cell assays are blocked by GHRP-receptor antagonists rather than GHRH antagonists (Raun 1998). Studies combining the two ligand types in rat systems report greater-than-additive GH release (Bowers 1991).
Rat anterior-pituitary membrane adenylate cyclase assays and dispersed primary rat pituitary cell GH-release assays are the standard in-vitro systems; transfected HEK293-type cells expressing cloned GHRH-R or GHS-R1a are used for binding and second-messenger work. In vivo characterization has used pentobarbital-anesthetized rats and conscious swine for plasma GH measurements. Plasma stability is typically assessed by incubating the peptide in rat, porcine or human plasma at 37 C and following degradation products by HPLC or LC-MS/MS.
The literature shows that unmodified GRF(1-29)-NH2 is cleaved rapidly at the Ala2-Ala3 bond by dipeptidyl peptidase IV in plasma (half-life on the order of minutes in porcine plasma), and that D-Ala2 substitution or N-terminal modification prevents this cleavage (Frohman 1989; Su 1991). For bench work this means lyophilized peptides should be reconstituted in an appropriate sterile, DPP-IV-free buffer immediately before assay, kept cold, and protected from repeated freeze-thaw; CJC-1295 additionally carries a reactive maleimide that will covalently bind free thiols, including albumin or cysteine-containing additives, in the assay medium (Jette 2005). The literature does not cover shelf-life of reconstituted solutions under typical lab storage, so users should establish this empirically.
All compounds referenced on this page are supplied by Liv Pure for in-vitro laboratory research only and are not for human or animal use. Nothing on this page is medical advice, and no statement here has been evaluated by the Food and Drug Administration. Product identity and purity for each lot are documented on the certificate of analysis; our Testing and Quality page explains what those certificates do and do not measure. Browse the GH Secretagogues category to see current lots.
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