Growth-hormone secretagogues & GH-axis peptides
IGF-1 LR3
Also known as Long R3 IGF-1 · LR3-IGF-I · Long arginine 3-IGF-1
A recombinant analogue of insulin-like growth factor-1 with an Arg3 substitution and N-terminal extension that sharply reduces binding to IGF-binding proteins.
In 60 seconds
A laboratory and animal-research reagent; not an approved medicine. In pigs it suppressed endogenous GH, IGFBP-3 and IGF-1; IGF-1 signalling carries hypoglycaemia risk; black-market products are frequently mislabelled.
- Identified a His-tagged LR3-IGF-I in a black-market product, illustrating mislabelled performance products.
- In pigs, LR3-IGF-I reduced growth and lowered GH, IGFBP-3 and endogenous IGF-1.
- Compared IGF-I and LR3-IGF-I effects on myoblast proliferation and differentiation in the presence of IGFBP-3.
Mechanism
Most circulating IGF-1 is held by IGF-binding proteins. LR3 was engineered to escape them, so it remains free and more potent at the IGF-1 receptor in cell culture — which is why it is a standard supplement in biotech cell-culture media.
Research status
A laboratory and animal-research reagent; not an approved medicine. Found in black-market "performance" products.
Key studies
Identified a His-tagged LR3-IGF-I in a black-market product, illustrating mislabelled performance products.
Detection of His-tagged Long-R³-IGF-I in a black market product — Growth Horm IGF Res, 2010 · PMID 20675162
In pigs, LR3-IGF-I reduced growth and lowered GH, IGFBP-3 and endogenous IGF-1.
Long [R3] insulin-like growth factor-I reduces growth, plasma growth hormone, IGF binding protein-3 and endogenous IGF-I concentrations in pigs — J Endocrinol, 1997 · PMID 9488001
Compared IGF-I and LR3-IGF-I effects on myoblast proliferation and differentiation in the presence of IGFBP-3.
Effect of recombinant porcine IGFBP-3 on IGF-I and long-R3-IGF-I-stimulated proliferation and differentiation of L6 myogenic cells — J Cell Physiol, 2004 · PMID 15254966
In an Alzheimer’s mouse model, intranasal LR3 altered plaque features but did not preserve cognition.
Intranasal long R3 insulin-like growth factor-1 treatment promotes amyloid plaque remodeling in cerebral cortex but fails to preserve cognitive function in male 5XFAD mice — J Alzheimers Dis, 2025 · PMID 39610283
Safety signals in the literature
In pigs it suppressed endogenous GH, IGFBP-3 and IGF-1; IGF-1 signalling carries hypoglycaemia risk; black-market products are frequently mislabelled.
Legal status (South Africa)
Not a registered medicine for human use in South Africa unless SAHPRA-registered under its own name; growth-hormone secretagogues are prohibited in sport under the WADA list. Supplied, where we stock it, strictly for laboratory research.
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Comparisons
Questions
What is IGF-1 LR3?
A recombinant analogue of insulin-like growth factor-1 with an Arg3 substitution and N-terminal extension that sharply reduces binding to IGF-binding proteins. Most circulating IGF-1 is held by IGF-binding proteins. LR3 was engineered to escape them, so it remains free and more potent at the IGF-1 receptor in cell culture — which is why it is a standard supplement in biotech cell-culture media.
What is the research status of IGF-1 LR3?
A laboratory and animal-research reagent; not an approved medicine. Found in black-market "performance" products.
What safety signals are reported for IGF-1 LR3?
In pigs it suppressed endogenous GH, IGFBP-3 and IGF-1; IGF-1 signalling carries hypoglycaemia risk; black-market products are frequently mislabelled.
Does Living Water Labs stock IGF-1 LR3?
Not at present. IGF-1 LR3 is profiled here for reference, with citations to the published literature. You can ask to be notified if we add it. Not a registered medicine for human use in South Africa unless SAHPRA-registered under its own name; growth-hormone secretagogues are prohibited in sport under the WADA list. Supplied, where we stock it, strictly for laboratory research.
More in GH secretagogues
Research reference only. This page summarises published literature; it is not medical advice and contains no guidance on human use. Products supplied by Living Water Labs are for laboratory research only.
