IGF-1 LR3
Also known as: Long R3 IGF-1 · Long-Arg3 IGF-1 · insulin-like growth factor 1 LR3
A synthetic long-acting analogue of insulin-like growth factor 1 with reduced IGF-binding-protein affinity, providing sustained systemic IGF-1 signalling with direct hippocampal-neurogenesis implications.
IGF-1 LR3 is a long-acting IGF-1 analogue with reduced IGFBP binding, providing direct systemic IGF-1 signalling with hippocampal-neurogenesis implications.
Evidence tier: C — preclinical / mechanistic evidence only
- Category
- Neurogenesis
- Half-life
- Approximately 20-30 hours plasma (vs ~10 minutes for native IGF-1)
Section 1
Overview
IGF-1 LR3 (Long R3 IGF-1) is a synthetic modified analogue of insulin-like growth factor 1 (IGF-1) — the primary anabolic mediator of GH-axis signalling — engineered with two structural modifications: an arginine substitution at position 3 (R3) that reduces binding to IGF-binding proteins (IGFBPs), and a 13-amino-acid N-terminal extension (Long) that further extends plasma half-life. The combined modifications produce a molecule with substantially greater bioavailable IGF-1 signalling than native IGF-1 at the same nominal dose.
The compound's research relevance to cognitive-endpoint applications rests on the well-established role of IGF-1 signalling in adult hippocampal neurogenesis and cognitive-plasticity mechanisms. Central IGF-1 receptor engagement drives adult neurogenesis in the dentate gyrus and supports BDNF-mediated synaptic plasticity — the same cognitive-plasticity mechanisms targeted by BDNF-inducing peptides through a different upstream pathway.
IGF-1 LR3 is used in research-peptide practice both as a standalone compound and as a downstream component of GH-axis research protocols (where GH-axis peptides raise endogenous IGF-1 via hepatic IGF-1 production). Direct cognitive-endpoint clinical trials of IGF-1 LR3 have not been completed, but the mechanistic framework and preclinical evidence support continued cognitive-relevance research interest.
Section 2
Discovery & History
- Developed as a modified IGF-1 analogue with structural changes designed to reduce IGFBP binding and extend plasma half-life relative to native IGF-1.
- Widely adopted in the sports-medicine and research-peptide communities despite absence of licensed clinical development.
- Preclinical cognitive-endpoint research has emerged from academic groups exploring the IGF-1 signalling contribution to adult hippocampal neurogenesis and cognitive-plasticity mechanisms.
- Not licensed as a medicine in any major jurisdiction; remains a research chemical.
- Banned by WADA for competitive athletes given the anabolic pharmacology.
Section 3
Mechanism of Action
- 1Direct IGF-1 receptor (IGF-1R) agonism providing the full spectrum of IGF-1 signalling effects — anabolic, metabolic, and neurotrophic — with substantially greater bioavailable signalling than native IGF-1 owing to the reduced IGFBP binding.
- 2Central IGF-1 receptor engagement in the hippocampus and other cognitively-relevant brain regions, driving adult hippocampal neurogenesis in the dentate gyrus — the primary cognitive-relevance mechanism-of-action angle.
- 3Support of BDNF-mediated synaptic plasticity — IGF-1 signalling supports BDNF expression and downstream cognitive-plasticity mechanisms, providing mechanistic convergence with the BDNF-inducing peptide family.
- 4Systemic anabolic effects on muscle, tendon, ligament, and bone tissue via the well-characterised IGF-1 systemic mechanism.
- 5Metabolic effects including improved glucose regulation and lipid profile modulation via the systemic IGF-1 mechanism.
- 6Reported effects on synaptic protein expression (PSD-95, synaptophysin), dendritic spine density, and long-term potentiation in preclinical models, providing cellular-level substrates for the cognitive-plasticity mechanism.
- 7Neuroprotective effects in preclinical models of cerebral ischaemia, oxidative stress, and neurodegenerative disease models, supporting a broader neuroprotection research angle.
Section 4
Researched Benefits
Findings reported in the published preclinical and clinical literature. Effects in research contexts do not constitute claims of therapeutic benefit in humans.
- 1Direct central IGF-1 signalling providing adult hippocampal neurogenesis induction — a distinctive cognitive-plasticity mechanism-of-action angle.
- 2Substantially greater bioavailable IGF-1 signalling than native IGF-1 owing to the reduced IGFBP binding — the pharmacological advantage over native IGF-1.
- 3Mechanistic convergence with the BDNF-inducing peptide family via IGF-1's support of BDNF signalling.
- 4Systemic anabolic effects on tissue-repair and body-composition endpoints providing broader research application contexts.
- 5Well-characterised IGF-1 signalling pharmacology from the extensive endogenous-IGF-1 research literature.
- 6Downstream mechanism of the GH-axis peptides — provides a direct-action alternative to raising endogenous IGF-1 via GH-axis stimulation.
- 7Neuroprotective effects in preclinical models providing broader neuroprotection research applications.
Section 5
Theoretical Dosing & Protocols
| Route | Dosage | Frequency | Duration |
|---|---|---|---|
| Subcutaneous injection (research) | Microgram-range doses in research protocols; typical research use is 20-50 mcg per dose | Once or twice daily in most research protocols | Research protocol dependent; chronic research use continues weeks to months |
Note: IGF-1 LR3's substantially extended half-life versus native IGF-1 permits less-frequent dosing than native IGF-1 protocols require.
Section 6
Administration Routes
- Subcutaneous injection — the primary research route.
- Intramuscular administration in some research contexts, particularly for localised anabolic-effect research applications.
- Oral administration is not viable — the peptide is degraded by gastrointestinal proteases.
- Intravenous administration in some acute-mechanistic research contexts.
Section 7
Safety Profile
Commonly reported
- · Injection-site reactions with subcutaneous administration.
- · Transient effects on blood glucose (typically mild hypoglycaemia via the IGF-1 hypoglycaemic mechanism) — requires monitoring in susceptible research subjects.
- · Occasional headache during initial dosing.
- · Fluid retention and mild peripheral oedema.
- · Occasional mild fatigue reported at higher doses.
Rare / theoretical
- · Severe hypoglycaemia in susceptible research subjects — the most clinically-significant acute concern.
- · Theoretical tumour-growth promotion in active malignancy — a substantial theoretical concern given IGF-1's role in cell proliferation.
- · Long-term chronic-use safety concerns extrapolated from the broader IGF-1 biology literature — chronic elevated IGF-1 is associated with increased cancer risk epidemiologically.
- · Acromegaly-like effects with chronic supraphysiological IGF-1 exposure.
- · Rare hypersensitivity reactions.
Contraindications
- · Not authorised for human use in the UK.
- · Active or historic malignancy — substantial theoretical contraindication via the IGF-1 proliferative mechanism.
- · Diabetes and severe glucose-metabolism disorders.
- · Pregnancy and lactation.
- · Concurrent use with insulin or oral hypoglycaemic agents without careful monitoring.
Section 8
UK & EU Regulatory Context
United Kingdom
Not a licensed medicine in the UK. Research chemical only.
European Union
Not approved by the EMA.
Section 9
Clinical Studies Summary
IGF-1 signalling in adult hippocampal neurogenesis
Foundational neuroscience characterisation of IGF-1 signalling's role in adult hippocampal neurogenesis in the dentate gyrus, establishing the mechanism-of-action framework for IGF-1's cognitive-relevance research applications and providing the neuroscience scaffold for the IGF-1 LR3 cognitive-endpoint research angle.
IGF-1 LR3 pharmacokinetic characterisation
Clinical pharmacology characterisation of IGF-1 LR3's pharmacokinetic profile relative to native IGF-1, demonstrating substantially extended plasma half-life and reduced IGFBP binding — the pharmacological advantages that motivated the analogue design.
IGF-1 in cognitive-plasticity research
Extensive research characterising IGF-1's contributions to synaptic plasticity, learning, and memory across preclinical models. Reports effects on synaptic protein expression, dendritic spine density, long-term potentiation, and BDNF expression that provide the cellular-substrate scaffold for the cognitive-endpoint research.
IGF-1 in Alzheimer's disease and cognitive-decline research
Research characterising IGF-1's role in Alzheimer's disease pathophysiology and its potential as a cognitive-therapeutic research target. Reports effects on amyloid-beta processing, tau pathology, and cognitive-endpoint outcomes in AD-model preparations, extending the cognitive-relevance research angle into disease-relevant contexts.
Section 10
Frequently Asked Questions
Section 10a
Practical Research Guidance
Cycle guidance
Reconstitution & storage
UK sourcing notes
Section 11
Sourcing for Laboratory Research
Sourcing IGF-1 LR3 for laboratory research
Researchers in the United Kingdom and elsewhere typically obtain IGF-1 LR3 from specialist research-chemical suppliers. Purity, third-party testing, and supplier transparency are the principal differentiators worth evaluating before placing an order. The two suppliers below are commonly referenced in UK research contexts.
Reminder: research peptides are sold strictly for in vitro and preclinical laboratory purposes. Importation or supply for human consumption is not permitted under UK medicines legislation.