What is Tesamorelin?

Tesamorelin is a synthetic 44-amino-acid peptide analogue of human growth hormone-releasing hormone (GHRH). The peptide is designed to stimulate endogenous growth hormone secretion through activation of the GHRH receptor in the pituitary gland.

The structure is based on native GHRH(1-44) with a trans-3-hexenoic acid group attached to the tyrosine residue at position 1, which protects the N-terminus from degradation and extends the peptide's half-life compared to native GHRH.

For UK research laboratories, tesamorelin serves as a reference compound for studies examining growth hormone physiology, metabolic regulation, and the role of the GHRH-GH-IGF-1 axis in cellular and systemic metabolism.

Tesamorelin operates through the following mechanism in research models:

GHRH Receptor Activation — Tesamorelin binds to the GHRH receptor (GHRHR), a Gs-coupled GPCR located on somatotroph cells in the anterior pituitary. Receptor activation increases intracellular cAMP, leading to protein kinase A activation and stimulation of growth hormone gene transcription and secretion.

Growth Hormone Axis Stimulation — The primary effect of tesamorelin is stimulation of endogenous growth hormone secretion. In research models, this leads to increased circulating GH levels, which subsequently stimulates hepatic IGF-1 production.

Metabolic Effects — Through the GH-IGF-1 axis, tesamorelin influences multiple metabolic pathways: increased lipolysis and free fatty acid availability, enhanced protein synthesis, and modulation of glucose metabolism.

Body Composition — Growth hormone is lipolytic and anabolic, increasing fat mobilisation while supporting lean tissue preservation. In cellular and animal models, tesamorelin's effects on body composition are mediated through GH receptor signalling in adipose tissue, muscle, and liver.

Tesamorelin is employed across multiple research domains in UK laboratories:

Endocrine Research — In vitro studies examine tesamorelin's effects on pituitary somatotroph function, GH secretion patterns, and the regulation of the GH-IGF-1 axis.

Metabolic Disease Research — Cellular models examine tesamorelin's effects on lipid metabolism, glucose homeostasis, and insulin sensitivity.

Body Composition Studies — In cellular and animal models, tesamorelin is studied in the context of fat distribution, lean mass preservation, and visceral adiposity.

Ageing Research — Growth hormone declines with age, and tesamorelin is used in cellular models to examine the effects of restoring GH axis activity.

Comparative GH Secretagogues — Tesamorelin is compared to other GH secretagogues (GHRP-2, GHRP-6, ipamorelin) in cellular and animal studies.

Tesamorelin is supplied as a lyophilised powder. Standard laboratory preparation:

• Bacteriostatic water (0.9% benzyl alcohol) recommended for reconstitution
• Typical concentrations: 1–10 mg/mL depending on assay requirements
• Solubility: The peptide is generally soluble in aqueous solutions; gentle vortexing may aid dissolution
• DPP-IV sensitivity: Although the N-terminal modification confers some protection, researchers should be aware of potential proteolytic degradation in serum-containing media
• pH: Maintain solutions at pH 6.5–7.5

• Lyophilised powder: −20°C, protected from light
• Reconstituted solution: 2–8°C, protected from light
• Stability: 7–14 days under refrigeration; aliquot and freeze at −20°C for extended studies
• Avoid: Repeated freeze-thaw cycles