Sermorelin is the synthetic form of GHRH(1-29)-NH2, the first 29 amino acids of human growth hormone-releasing hormone with an amidated C-terminus. That fragment turned out to carry the full receptor activity of the 44-residue native hormone, and for roughly four decades it has served as the baseline molecule against which other GHRH analogs are measured.
Sermorelin also has a regulatory history that sets it apart from most research peptides: a sermorelin drug product was once approved in the United States. This overview covers how GHRH was discovered, why the 1-29 fragment became the standard, how the GHRH receptor signals, what laboratories have used the peptide for, and the limits of what the literature can say about it.
At a glance
- Class: Synthetic 29-amino-acid peptide; GHRH receptor agonist
- Origin: N-terminal fragment of human GHRH, a hormone first isolated in 1982; the hypothalamic sequence was confirmed by Ling and colleagues in 1984
- Structure: Tyr-Ala-Asp-Ala-Ile-Phe-Thr-Asn-Ser-Tyr-Arg-Lys-Val-Leu-Gly-Gln-Leu-Ser-Ala-Arg-Lys-Leu-Leu-Gln-Asp-Ile-Met-Ser-Arg-NH2; C149H246N44O42S; 3357.9 g/mol; CAS 86168-78-7
- Main research areas: GHRH receptor activation and cAMP signaling, structure-activity relationships, somatotroph regulation, reference ligand for newer analogs
- Regulatory status: A sermorelin drug product was previously FDA approved and was discontinued in 2008; WADA S2
Structure and origin
The existence of a hypothalamic factor that stimulates growth hormone was proposed decades before anyone could isolate it. The breakthrough came in 1982, when two groups purified GHRH from pancreatic tumors that had caused acromegaly in patients without pituitary tumors (Thorner, 2008). Two years later, Ling and colleagues isolated GHRH from human hypothalamic tissue, determined its primary structure and showed by synthesis that it matched the 44-residue tumor-derived peptide (Ling et al., 1984).
Researchers quickly found that the full length was not needed. Truncated peptides ending at residue 29, with a C-terminal amide, kept essentially full activity in pituitary assays. Shorter fragments lost potency sharply. GHRH(1-29)-NH2 therefore became the minimal active unit, and the synthetic version received the name sermorelin.
The sequence contains only standard L-amino acids. Several positions are known weak points: Ala at position 2 allows cleavage by dipeptidyl peptidase-4, Asn at position 8 can deamidate, and Met at position 27 can oxidize. These liabilities explain why sermorelin is cleared rapidly, and they are exactly the positions that later analogs such as CJC-1295 modify.
Mechanism: what the research shows
Early structure-activity work used membranes from rat anterior pituitary and measured adenylate cyclase activation as the readout. Robberecht and colleagues showed that the N-terminal residues are critical: removing or altering the first few amino acids reduced activation, and certain substitutions turned the peptide into a weak partial agonist or antagonist (Robberecht et al., 1985). This established GHRH(1-29) as a scaffold that could be tuned in either direction.
The receptor itself was cloned from pituitary tissue in 1992. It is a class B G protein-coupled receptor expressed mainly in anterior pituitary somatotrophs (Mayo, 1992). Binding activates Gs, adenylate cyclase and protein kinase A. Downstream, the pathway supports GH secretion, transcription of the GH gene and somatotroph proliferation. Studies of mice carrying a mutated GHRH receptor, which have small pituitaries with few somatotrophs, highlighted that proliferative role (Mayo et al., 2000).
Key areas of study
Receptor pharmacology and cAMP signaling
Sermorelin is used as the reference agonist in GHRH receptor binding and cAMP assays, whether in pituitary cells, membrane preparations or cell lines engineered to express the cloned receptor (Mayo, 1992). New analogs are usually reported relative to GHRH(1-29)-NH2.
Structure-activity relationships
The adenylate cyclase studies of the mid-1980s mapped which residues tolerate change and which do not (Robberecht et al., 1985). That map guided decades of analog design, including stabilized agonists and the GHRH antagonists used in cancer biology research.
Somatotroph biology
Questions about how GHRH controls somatotroph number, GH gene expression and the interplay with somatostatin rely on a well-characterized native agonist. Mayo and colleagues reviewed this body of work, including the genetic mouse models (Mayo et al., 2000).
Clinical pharmacology history
Sermorelin was developed as a diagnostic agent for assessing pituitary GH reserve and was studied in children with idiopathic growth hormone deficiency. A 1999 review summarized that clinical program (Prakash and Goa, 1999). Its relevance here is historical: it documents how the peptide was characterized, not anything about the research reagent.
What the evidence does not show
- Much of the clinical literature dates from the late 1980s and 1990s and concerns a specific pharmaceutical product, not research-grade material.
- Sermorelin’s short half-life means many observations are tied to particular experimental timing; results from long-acting analogs cannot be assumed to apply.
- Pituitary cell and membrane assays capture receptor activation, but they do not reproduce the hypothalamic and somatostatin inputs that shape GH release in an intact animal.
- Claims circulating online about sermorelin in adults are generally not supported by adequately sized controlled studies, and no current approved product exists in the United States.
Regulatory status
A prescription sermorelin acetate product was previously approved in the United States. It was discontinued in 2008, and the FDA later determined that it was not withdrawn for reasons of safety or effectiveness. The World Anti-Doping Agency lists GHRH and its analogs under S2 (peptide hormones, growth factors, related substances and mimetics). The sermorelin sold by Rogue Compounds is a research reagent, not an approved drug product.
Handling and storage in the lab
Keep lyophilized sermorelin sealed and refrigerated at 2–8°C (36–46°F), protected from light.
Sourcing and documentation
Rogue Compounds has sermorelin made in small batches. Each vial carries a batch number and a QR code that opens the independent U.S. testing lab’s own report for that batch, and the same batch COA appears on the product page and in the COA Library.
View Sermorelin on Rogue Compounds
References
- Thorner MO. The discovery of growth hormone-releasing hormone: an update. J Neuroendocrinol. 2008;20(6):653-654. PMID 18601685
- Ling N, et al. Isolation, primary structure, and synthesis of human hypothalamic somatocrinin: growth hormone-releasing factor. Proc Natl Acad Sci USA. 1984;81:4302-4306. PMID 6431406
- Robberecht P, et al. Structural requirements for the activation of rat anterior pituitary adenylate cyclase by growth hormone-releasing factor (GRF). Endocrinology. 1985;117:1759-1764. PMID 2994998
- Mayo KE. Molecular cloning and expression of a pituitary-specific receptor for growth hormone-releasing hormone. Mol Endocrinol. 1992;6(10):1734-1744. PMID 1333056
- Mayo KE, et al. Regulation of the pituitary somatotroph cell by GHRH and its receptor. Recent Prog Horm Res. 2000;55:237-266. PMID 11036940
- Prakash A, Goa KL. Sermorelin: a review of its use in the diagnosis and treatment of children with idiopathic growth hormone deficiency. BioDrugs. 1999;12(2):139-157. PMID 18031173
Research use only. Rogue Compounds products are sold strictly for laboratory research. They are not for human or veterinary use, and nothing in this article is medical advice. The studies cited here describe published research, not this product or any use of it.