The classical growth-hormone axis has three broad steps documented in endocrinology literature. First, the hypothalamus releases growth-hormone-releasing hormone (GHRH), which signals the pituitary gland. Second, the pituitary responds by releasing growth hormone (GH, also called HGH) into circulation. Third, GH acts on the liver — and to a lesser extent other tissues — to stimulate production of IGF-1, which then mediates much of GH's downstream effect on growth and metabolism.
Understanding this chain matters because different research peptides and compounds act at different points along it, and confusing those points is one of the most common sources of misunderstanding in general peptide discussion.
GHRH-analog research peptides, such as Tesamorelin (part of REVIVE LAB UAE's actual catalog), act at the first step — stimulating the pituitary to release the body's own GH, rather than introducing GH directly. This preserves the body's natural pulsatile release pattern and feedback regulation, which is part of why GHRH-analog research carries a different profile than direct GH administration.
HGH itself, whether pituitary-derived or pharmaceutical recombinant somatropin, represents the second step directly — it is the hormone itself, not a stimulator of its release. HGH is a regulated prescription pharmaceutical in the UAE and is not sold by REVIVE LAB UAE.
IGF-1 sits at the third step, as the downstream mediator that GH signaling ultimately depends on for many of its effects on tissue growth. Native IGF-1's tight regulation by IGF-binding proteins (IGFBPs) makes it a difficult research tool on its own, which is why engineered analogs like IGF-1 LR3 — designed to reduce IGFBP binding and extend functional activity — appear frequently in published growth-factor research focused specifically on this final step.
IGF-1 LR3 is not part of REVIVE LAB UAE's catalog. It is discussed here purely to complete the picture of how the axis works, not as a product recommendation.
A researcher interested in pituitary-level regulation, feedback loops, or the effects of stimulating endogenous hormone release is working with a fundamentally different research question than one interested in isolated, receptor-level IGF-1 signaling. Compounds that act at different steps of this axis are not interchangeable tools, even though they are often discussed together under the broad umbrella of "growth hormone axis" research.
This distinction also matters for regulatory and sourcing reasons: HGH is a regulated pharmaceutical, GHRH-analog research peptides like Tesamorelin occupy their own documented research-peptide category, and unmodified downstream signaling analogs like IGF-1 LR3 occupy yet another category — unregulated research chemical, not sold by REVIVE LAB UAE.
REVIVE LAB UAE's documented catalog includes Tesamorelin, which sits at the GHRH/pituitary-stimulation step of this axis, tested and supplied with lot-specific Certificates of Analysis. It does not include HGH or IGF-1 LR3, which occupy the other two steps described here.
This primer is published as general endocrinology background for researchers trying to understand how these different compounds relate to one another, not as a guide to using any of them.