Sermorelin is synthetic GHRH (1–29) amide: the first 29 residues of the 44-amino-acid human growth hormone-releasing hormone, C-terminally amidated, and the fragment that decades of endocrine work showed carries essentially all of the receptor-binding information of the full hormone. That truncation is the entire point of the molecule. If residues 30 to 44 contribute nothing measurable to receptor activation, then a 29-residue peptide is a cheaper, easier-to-synthesise and more chemically tractable tool for probing the GHRH receptor than the intact hormone.
This page explains where the sequence comes from, how it acts on the pituitary, what has been published, and how the material is specified and handled in a laboratory. Sermorelin is supplied as a lyophilized powder for laboratory research use only.
Sermorelin at a glance
| Property | Value |
|---|---|
| Chemical identity | GHRH (1–29) amide; growth hormone-releasing factor 1-29 |
| Sequence | 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 |
| Length | 29 residues, C-terminally amidated |
| CAS number | 86168-78-7 |
| Molecular formula | C149H246N44O42S |
| Molecular weight | 3357.93 g/mol |
| Receptor | GHRH receptor (GHRHR), class B GPCR on pituitary somatotrophs |
| Signalling | Gs → adenylyl cyclase → cyclic AMP → protein kinase A |
| Main degradation route | Dipeptidyl peptidase-4 cleavage after Ala2 |
| Sizes supplied | 2 mg, 5 mg, 10 mg lyophilized vials |
| Purity specification | ≥99% by RP-HPLC with lot-matched COA |
Origin and structure
Human GHRH was isolated in 1982 from pancreatic tumours in patients with acromegaly — an unusual discovery route, made possible because the tumours produced the hypothalamic hormone in quantities that hypothalamic tissue never would. The isolated peptide was 44 residues. Structure-activity work that followed established that the N-terminal 29 residues retained full biological potency, and that the N-terminus in particular is essential: removing even the first residue collapses activity.
Sermorelin is that 29-residue fragment with a C-terminal amide replacing the free carboxylate. Amidation is the modification that most distinguishes it from a naive truncation; it removes a terminal negative charge and improves receptor engagement, and it is one of the identity features to confirm on a certificate. The peptide contains a single methionine at position 27, which is the residue most vulnerable to oxidation and the reason methionine oxidation appears repeatedly in stability discussions of GHRH analogues.
Structurally, sermorelin belongs to the secretin-glucagon superfamily alongside VIP, PACAP, secretin and glucagon. All engage class B G protein-coupled receptors by the same two-domain mechanism: the C-terminal portion of the peptide docks into the large extracellular domain of the receptor, and the N-terminal residues then insert into the transmembrane core to trigger signalling. This explains why C-terminal truncation is tolerated far better than N-terminal truncation.
How sermorelin is thought to work
Sermorelin binds the GHRH receptor on pituitary somatotrophs. The receptor couples to Gs, raising cyclic AMP and activating protein kinase A, which increases both growth hormone gene transcription and the release of stored hormone. Sustained exposure is also associated in the literature with somatotroph proliferation.
The feature that makes the GHRH receptor useful as a research target is that the resulting release remains under physiological control. Somatostatin tone continues to oppose secretion, and the negative feedback exerted by IGF-1 stays intact. A GHRH agonist therefore amplifies an existing regulated rhythm rather than replacing it — unlike administration of recombinant growth hormone itself, which bypasses the axis entirely. In animal models this shows as preserved pulsatility, which is the specific reason sermorelin appears in studies of hypothalamic-pituitary regulation.
Sermorelin is also short-lived. Dipeptidyl peptidase-4 cleaves the peptide after the alanine at position 2, and reported plasma half-life is a matter of minutes. That is a limitation for some experimental designs and an advantage for others: brief exposure windows are exactly what is needed to study pulsatile receptor signalling rather than continuous occupancy. Analogues built to resist this cleavage — modified GRF 1-29 with its substituted position 2, and tesamorelin with its N-terminal acyl group — exist precisely because of it.
What research has examined
Pituitary and hypothalamic physiology
The core use is as a reference GHRH receptor agonist in cell and animal work: receptor binding, cyclic AMP accumulation, somatotroph responsiveness, and characterisation of pulsatile secretion patterns in intact animals. In this role sermorelin functions as a standard rather than as a subject of study.
Diagnostic endocrinology
Sermorelin acetate was formerly marketed as a prescription product in the United States, used in growth hormone stimulation testing and in paediatric growth hormone deficiency. It was withdrawn from the US market in 2008 for commercial rather than safety reasons. Those clinical data concern an approved pharmaceutical product used under medical supervision, not research-grade material.
Comparative structure-activity work
Sermorelin is the standard comparator against which stabilised GHRH analogues are measured, which is why it appears constantly in the tesamorelin and modified GRF 1-29 literature. Direct comparisons are covered in tesamorelin vs sermorelin and CJC-1295 vs sermorelin.
Combination pharmacology
A distinct body of work examines GHRH receptor agonists together with growth hormone secretagogue receptor agonists such as ipamorelin, since the two receptors act on the same cell through different second-messenger systems — cyclic AMP and phospholipase C respectively — and their combined effect has been reported as more than additive in some models. Pre-blended research material exists for this design.
Forms and sizes we supply
Sermorelin is stocked as a lyophilized powder in 2 mg (USD 45), 5 mg (USD 75) and 10 mg (USD 120) sealed vials. At 3357.93 g/mol, a 5 mg vial contains approximately 1.49 micromoles — ample for receptor pharmacology, which operates in the nanomolar range, and consumed far faster by animal work. The full GHRH group sits under GHRH analogs, with the broader category under growth hormone and performance peptides.
Reconstitution and storage in a laboratory context
The calculation: a 5 mg vial reconstituted with 2 mL of bacteriostatic water gives 2.5 mg/mL, equivalently 2,500 mcg/mL; 0.1 mL (10 units on a U-100 syringe) contains 250 mcg. In molar terms, 2.5 mg/mL of a 3357.93 g/mol peptide is approximately 745 micromolar, so a receptor assay running at 10 nanomolar requires roughly a 75,000-fold dilution — done in stages, not in one step.
Two stability points are specific to this peptide. The methionine at position 27 is oxidation-sensitive, so stock solutions are protected from air and light. And in any biological matrix containing active DPP-4, degradation begins immediately, which is a methodological consideration rather than a storage one. Lyophilized vials are stored at −20 °C, protected from light and moisture; reconstituted material is aliquoted and kept cold. Detail is in the reconstitution guide and the storage guide.
Purity, COA and how to read one
Each lot is purified by reversed-phase HPLC to at least 99% with mass confirmation and a lot-matched certificate. Three checks matter here. First, the C-terminal amide: the observed mass should match 3357.93 g/mol, and a value approximately 1 Da higher indicates the free acid rather than the amide. Second, oxidation: a +16 Da satellite in the mass spectrum, or an early-eluting shoulder on the chromatogram, points to oxidised methionine at position 27. Third, deletion sequences: at 29 residues this is a moderately long synthesis, and a chain missing a single residue can co-elute closely with the target, so chromatographic resolution matters as much as the headline percentage. Our COA reading guide works through these on real documents.
Regulatory status
Sermorelin acetate was an approved prescription product in the United States and was withdrawn from the market in 2008; some sermorelin is prepared by compounding pharmacies under prescription in certain jurisdictions. None of that applies to the material sold here, which is research use only: for in-vitro and preclinical laboratory investigation by qualified researchers, not for human or veterinary administration. Research-grade peptide is not a pharmaceutical product and carries none of the associated regulatory assurances.
Related peptides and further reading
Within the GHRH family, modified GRF 1-29 is the stabilised short analogue, CJC-1295 with DAC the long-acting albumin-binding version, and tesamorelin the acylated full-length analogue. On the secretagogue side, ipamorelin, GHRP-2 and GHRP-6 act on an entirely different receptor. The whole landscape is mapped in the GH secretagogue landscape explained.