Growth hormone peptides: the complete overview of the GH axis

Research context (RUO): This hub gives an overview of the peptides that touch the growth hormone axis (GH axis) in research. All substances mentioned are supplied solely for in-vitro laboratory research and are not intended for human or animal use.

Growth hormone peptides: the complete overview of the GH axis

“Growth hormone peptides” is a collective name for a whole family of research molecules that act at different points on the growth hormone axis — the chain of signals that begins in the brain and ends in growth and repair processes in tissue. Because there are many, this page is a overview (hub): for each group we briefly explain the role and link to the separate pillar with the details. This way you quickly find the right entry point for your research.

How the GH axis works — in plain language

The pituitary gland in the brain releases growth hormone (GH) under the influence of two natural signals. One is GHRH (the “production” signal), the other is ghrelin (an amplifying “release” signal via a separate receptor). Once released, GH triggers in the liver and tissues the production of IGF-1 — the growth factor that carries out many of the actual effects. Research peptides mimic these signals or intervene in them, and therefore fall into a few clear groups.

GHRPs & ghrelin agonists

These peptides mimic ghrelin and thereby trigger GH release via a separate receptor. The best known are GHRP-2, GHRP-6, hexarelin and the selective ipamorelin. They differ in potency and in side effects (such as hunger or cortisol) — a direct comparison is in GHRP-2 vs GHRP-6 vs hexarelin.

GHRH analogues

This group precisely mimics the GHRH signal. CJC-1295 is the long-acting variant, sermorelin the short “base” analogue, and tesamorelin is studied mainly around visceral fat. Because GHRPs and GHRH analogues act on different receptors, they are often combined in research — see Ipamorelin vs CJC-1295 vs sermorelin.

The IGF axis

Downstream of GH sits IGF-1. IGF-1 LR3 is the long-acting variant, IGF-1 DES the short, locally acting one, and MGF and PEG-MGF are splice variants that arise in muscle tissue under mechanical load.

Myostatin inhibition

Not every molecule drives growth — some instead remove a brake. Myostatin (GDF-8) is the natural brake on muscle growth, and follistatin-344 is studied as an antagonist that removes that brake.

In the lab: handling & dissolving

These peptides are supplied as a freeze-dried powder that is reconstituted before use. See reconstitute peptides and which liquid you choose.

Quality & purity

Every relevant batch is independently HPLC-tested by an external laboratory; the CoA is publicly verifiable per batch. See also why we rejected a batch.

Frequently asked questions

What are growth-hormone peptides?
A collective name for research molecules that act on the GH axis: GHRPs/ghrelin agonists, GHRH analogues, IGF variants and myostatin inhibitors. They are studied exclusively for laboratory research.

What is the difference between a GHRP and a GHRH analogue?
A GHRP mimics ghrelin (release signal via a separate receptor); a GHRH analogue mimics the GHRH signal (production). They act on different receptors and are therefore often studied together.

What does IGF-1 do in this story?
IGF-1 sits downstream: growth hormone triggers its production, and IGF-1 carries out many of the effects. Variants such as IGF-1 LR3 and IGF-1 DES are studied separately.

Why myostatin inhibitors in this category?
Because muscle growth is also determined by brakes: myostatin (GDF-8) limits growth, follistatin removes that brake. Both belong to the broader GH/muscle research.

May I use these peptides?
No. All GH-axis peptides are intended solely for in-vitro laboratory research (RUO), not for human or animal use.

Read more & research at Peplife

• View all GH axis peptides
• GHRPs: GHRP-2 · GHRP-6 · hexarelin · ipamorelin
• GHRH: CJC-1295 · sermorelin · tesamorelin
• IGF: IGF-1 LR3 · IGF-1 DES · MGF & PEG-MGF
• Myostatin: GDF-8 · follistatin-344
• Comparisons: GHRP-2 vs GHRP-6 vs hexarelin · Ipamorelin vs CJC-1295 vs sermorelin

Sources: Growth hormone secretagogues: GHRH & GHRP synergy (PMC) · Endotext — Growth Hormone Axis

Research Use Only. All products are supplied exclusively for in vitro laboratory research. Not intended for diagnostic or therapeutic use in humans or animals, and not approved by the EMA or FDA.