Tesamorelin: GHRH Analog Research Overview

Growth hormone-releasing hormone is a 44-residue hypothalamic peptide that was first isolated in 1982. In the pituitary it binds receptors on somatotroph cells and stimulates the synthesis and release of growth hormone (GH).

Native GHRH is short-lived in circulation, mainly because dipeptidyl peptidase-4 (DPP-4) cleaves it between Ala² and Asp³. Tesamorelin keeps the complete human GHRH(1–44) sequence and adds a trans-3-hexenoyl group to Tyr¹. That N-terminal cap protects the cleavage site, so the analog stays intact longer while keeping affinity for the receptor.

Sequence (one-letter code), with the hexenoyl group on the first residue:

(trans-3-hexenoyl)-YADAIFTNSYRKVLGQLSARKLLQDIMSRQQGESNQERGARARL-NH2

Several research peptides act on the GH axis. They differ in length, modification and receptor:

Tesamorelin, sermorelin and CJC-1295 all signal through the GHRH receptor. Ipamorelin works through a separate receptor, which is why the two families are often compared in receptor-pharmacology studies.

The GHRH receptor belongs to the secretin family (class B) of G protein-coupled receptors. The pathway studied with Tesamorelin runs as follows:

1. The peptide binds the extracellular domain and transmembrane core of GHRHR on pituitary somatotrophs.
2. The receptor couples to G_s, activating adenylyl cyclase and raising intracellular cAMP.
3. cAMP activates protein kinase A, which phosphorylates the transcription factor CREB and increases transcription of the GH gene and of Pit-1.
4. Calcium influx through voltage-gated channels supports GH secretion from stored granules.

GH release stays under the control of somatostatin, which inhibits the same cells, so GHRH analogs are typically studied as modulators of a pulsatile, feedback-regulated system. Downstream, GH stimulates hepatic production of insulin-like growth factor 1 (IGF-1), a common readout in preclinical work.

Common in vitro and preclinical approaches include:

• Receptor assays: cAMP accumulation (HTRF or luminescence formats) in cell lines expressing recombinant human GHRHR, with native GHRH(1–44) or sermorelin as reference agonists.
• Binding studies: competition against a labeled GHRH ligand to compare affinity across analogs.
• Pituitary cell cultures: GH secretion from primary somatotrophs, measured by ELISA, with somatostatin as a functional antagonist.
• Stability assays: incubation with DPP-4 or plasma, followed by LC-MS, to compare degradation of Tesamorelin with unmodified GHRH.
• Preclinical models: GH and IGF-1 measurements in animal studies, as in the original non-clinical pharmacology of TH9507.

NuRev lots are tested by independent third-party laboratories. For a 44-residue peptide, a useful Certificate of Analysis shows:

• Identity by mass spectrometry, matched to the expected molecular weight (about 5136 Da)
• Purity by HPLC, with the chromatogram
• A lot number identical to the one printed on the vial
• The name of the testing laboratory and the test date

Each NuRev vial label carries a QR code that opens the matching lot’s documents. All published reports are in the certificate of analysis library; see how to read a peptide COA for what each section means.

Tesamorelin contains a methionine residue (Met²⁷), which can oxidize, and several sites prone to deamidation. General practice for lyophilized peptides applies:

• Store the sealed vial at −20 °C, protected from light and moisture. Short-term storage at 2–8 °C is acceptable.
• Let the vial reach room temperature before opening, to avoid condensation.
• After reconstitution, aliquot the solution and avoid repeated freezing and thawing.

More detail is in our peptide storage guide. NuRev supplies Tesamorelin 10 mg for laboratory research use only.

1. Guillemin R, Brazeau P, Böhlen P, et al. Growth hormone-releasing factor from a human pancreatic tumor that caused acromegaly. Science, 1982; 218(4572): 585–587.
2. Mayo KE. Molecular cloning and expression of a pituitary-specific receptor for growth hormone-releasing hormone. Molecular Endocrinology, 1992; 6(10): 1734–1744.
3. Ferdinandi ES, Brazeau P, High K, et al. Non-clinical pharmacology and safety evaluation of TH9507, a human growth hormone-releasing factor analogue. Basic & Clinical Pharmacology & Toxicology, 2007; 100(1): 49–58.
4. Falutz J, Allas S, Blot K, et al. Metabolic effects of a growth hormone-releasing factor in patients with HIV. New England Journal of Medicine, 2007; 357(23): 2359–2370.