What it is
GHRH is the hypothalamus's signal to release growth hormone. It is a chain of 44 amino acids ending in an amidated leucine, cut from a 108-residue precursor (UniProt P01286, residues 32–75). At 44 residues it is just over the 40-amino-acid line US biologics rules (21 CFR 600.3) use for proteins — see the peptide-or-protein entry — and the library carries it because two of its entries, sermorelin and tesamorelin, are copies of it.
It goes by several names: GRF and GHRF (growth hormone-releasing factor, the older name), somatoliberin, and somatocrinin.
How it was found
The hormone exists in the hypothalamus in quantities too small to sequence. The breakthrough came from tumours. In November 1982 two groups independently reported growth hormone-releasing peptides from human pancreatic tumours that had caused acromegaly — the overgrowth disease of excess growth hormone:
- Guillemin and colleagues (Science, PMID 6812220) isolated a 44-amino-acid peptide, published its full sequence, and showed the synthetic copy "has full biological activity in vitro and in vivo specifically to stimulate the secretion of immunoreactive growth hormone". They noted it was "identical in biological activity" to the still uncharacterised factor in hypothalamic extracts.
- Rivier and colleagues at the Salk Institute (Nature, PMID 6292724) characterised a growth hormone-releasing factor from a pancreatic islet tumour, with its sequence analysis published the same month (Spiess et al., PMID 6295453).
Esch et al. (PMID 7159418) also described a 40-residue form from the same kind of tumour.
Which part does the work
The two 1982 tumour peptides were not quite the same length. Guillemin's group reported 44 residues ending in an amidated leucine; the Salk group's sequence analysis (Spiess et al., PMID 6295453) established the first 39 residues by Edman degradation and proposed that alanine at position 40, as a free acid, ended its form. The overlap is exact — the 40-residue form is the same chain stopping four residues sooner.
The same paper settled which stretch matters. Synthetic versions ending at residue 40 (free acid or amide) and a version ending at residue 29 (amide) "show equivalent in vitro activities" to the natural tumour peptide, and the authors concluded that the C-terminal end "does not appear to contribute significantly" to its potency. That 29-residue fragment is the molecule later developed as sermorelin:
| Stretch | Residues | Sequence (human) |
|---|---|---|
| The active core (sermorelin) | 1–29 | YADAIFTNSYRKVLGQLSARKLLQDIMSR |
| Ends the 40-residue form | 30–40 | QQGESNQERGA |
| Completes the 44-residue hormone | 41–44 | RARL-NH2 |
Split by this library from the Guillemin (1982) sequence and UniProt P01286. Spiess and colleagues also noted, from sequence similarity, that the hormone belongs to the glucagon–secretin family of peptides, closest to the pig gut peptide PHI.
The GHRH test
Because it acts directly on the pituitary, GHRH has been used to test whether the pituitary can release growth hormone. Endocrine papers name the GHRH + arginine test among the recognised stimulation tests for adult growth hormone deficiency, alongside the insulin tolerance test, the glucagon test and macimorelin (2024 review, J Endocrinol Invest, PMID 38461479); one 2021 study used a lack of response to it as its reference standard (PMID 32335555). The same 2024 review cites "the unavailability of the GHRH all over the world" as a reason other tests are expected to replace it. A 2011 meta-analysis of 23 studies (over 1,100 patients) found several stimulation tests accurate but most assessed in only one or two studies (PMID 21856789). Interpreting any test belongs to the endocrinologist who ordered it.
What it does
Released by the hypothalamus, GHRH, in UniProt's wording, "acts on the adenohypophyse" — the front lobe of the pituitary — "to stimulate the secretion of growth hormone". It works against somatostatin, which holds growth hormone release back, and alongside the stomach hormone ghrelin, which works through a different receptor. Growth hormone then raises insulin-like growth factor 1, which carries much of its effect.
| What is described | How firm |
|---|---|
| Triggers growth hormone release | Human and animal work since 1982; UniProt |
| Tumours releasing it cause acromegaly | Human case material (the 1982 tumours) |
| Analogue tesamorelin reduces HIV-associated abdominal fat | Approved indication (see its entry) |
| Anti-ageing or body-composition benefit in healthy adults | No approval found for GHRH or either analogue |
The drugs built on it
| Drug | What it copies | FDA status (openFDA Drugs@FDA, 2026-11-02) |
|---|---|---|
| Sermorelin (Geref) | GHRH 1–29 | NDA019863 and NDA020443, both listed as discontinued |
| Tesamorelin (Egrifta) | modified GHRH 1–44 | BLA022505, prescription |
The research-market compound CJC-1295 is also a modified GHRH 1–29 and is not approved. GHRH itself is not an approved US medicine.
Where it stands
- Not a medicine itself; the template for two approved drugs, one now discontinued.
- Research volume: 4,541 PubMed records for growth hormone-releasing hormone or GHRH in the title or abstract, 263 indexed as randomised trials; ClinicalTrials.gov lists 452 studies under the full name and 59 under "GHRH" (searched 2026-11-02).
Related reading
Somatropin is the growth hormone GHRH releases, and MK-677 a non-peptide that raises it by the ghrelin route instead.