Receptor Grade IGF-1 LR3 (1mg)

IGF-1 LR3 (Long R3 IGF-1, Insulin-Like Growth Factor-1 Long Arg3, 1mg): A Recombinant 83-Amino-Acid Analogue of Human Insulin-Like Growth Factor 1 (IGF-1, Somatomedin C) with an N-Terminal 13-Amino-Acid Extension Peptide and an Arginine Substitution at Position 3 (Glutamic Acid → Arginine), Designed for Enhanced Potency, Extended Half-Life, and Reduced IGF-Binding Protein (IGFBP) Affinity — the 1mg Vial Format (Larger Research Quantity) for Investigational Research in Muscle Hypertrophy, Fat Loss, Tissue Repair, Recovery, Anti-Aging, and Metabolic Health

IGF-1 LR3 (also known as Long R3 IGF-1, Long Arg3 IGF-1, or IGF-1 Long R3) is a recombinant 83-amino-acid analogue of human insulin-like growth factor 1 (IGF-1, also known as somatomedin C), with a molecular weight of approximately 9.11 kDa (9,111 Daltons). This 1mg vial format contains the same IGF-1 LR3 peptide as the 100mcg vial, but in a larger quantity (1mg = 1000mcg, ten times the 100mcg vial), making it suitable for more extensive research programs, longer-duration studies, or higher-dose protocols that require larger quantities of the peptide. IGF-1 LR3 was engineered by GroPep (an Australian biotechnology company, later acquired by Sigma-Aldrich) in the 1990s as a long-acting, high-potency analogue of native IGF-1, specifically designed to overcome two key limitations of native IGF-1 for research and potential therapeutic use: (1) short half-life — native IGF-1 has a very short circulating half-life (~10-20 minutes for the free form) due to rapid renal clearance and proteolytic degradation; (2) high affinity for IGF-binding proteins (IGFBPs) — native IGF-1 binds with high affinity to a family of six IGF-binding proteins (IGFBP-1 through IGFBP-6, with IGFBP-3 being the most abundant, binding ~75-80% of circulating IGF-1 in a ternary complex with IGFBP-3 and the acid-labile subunit [ALS]), which regulate IGF-1 bioavailability, half-life, and tissue access, and can both inhibit and potentiate IGF-1 actions depending on context. To address these limitations, IGF-1 LR3 incorporates two key structural modifications to the native 70-amino-acid IGF-1 molecule: (1) an N-terminal 13-amino-acid extension peptide (the "Long" or "L" in LR3) — a 13-residue peptide added to the N-terminus of IGF-1, which increases the molecular size from 70 to 83 amino acids (~7.65 kDa → ~9.11 kDa), reducing renal clearance (larger molecules are filtered less efficiently by the glomerulus) and increasing circulating half-life; (2) an arginine substitution at position 3 (the "R3" in LR3) — the native glutamic acid (Glu, E, a negatively charged acidic amino acid) at position 3 of IGF-1 is replaced with arginine (Arg, R, a positively charged basic amino acid), which significantly reduces the peptide's affinity for IGF-binding proteins (IGFBPs), particularly IGFBP-1, IGFBP-2, and IGFBP-3, because the glutamic acid at position 3 is a key residue involved in IGFBP binding (the negatively charged glutamate forms important electrostatic interactions with positively charged residues in the IGFBP N-terminal binding domain; replacing it with positively charged arginine disrupts these interactions and reduces binding affinity by approximately 100-1000 fold compared to native IGF-1). These two modifications together give IGF-1 LR3 its characteristic properties: increased potency (approximately 2-3 times more potent than native IGF-1 in many in vitro and in vivo assays, due to reduced IGFBP binding which increases the bioavailable "free" fraction of the peptide that can access and activate IGF-1 receptors), extended half-life (approximately 6-12 hours in rodents and larger animals, compared to ~10-20 minutes for free native IGF-1, due to reduced renal clearance from the larger molecular size and reduced proteolytic degradation), and reduced IGFBP affinity (which means more of the peptide is in the biologically active "free" form, less is sequestered by IGFBPs, and the peptide can more readily access tissues and activate receptors — although it also means less of the IGFBP-mediated transport and tissue-targeting functions, and potentially altered pharmacodynamics). IGF-1 LR3 exerts its biological effects primarily by binding to and activating the IGF-1 receptor (IGF-1R, also known as CD221) — a transmembrane receptor tyrosine kinase (RTK) of the insulin receptor family, which also includes the insulin receptor (IR), IGF-2 receptor (IGF-2R, a mannose-6-phosphate receptor that does not signal like IGF-1R), and the insulin receptor-related receptor (IRR). The IGF-1R is a heterotetrameric receptor consisting of two extracellular α-subunits (which contain the ligand-binding domain) and two transmembrane β-subunits (which contain the intracellular tyrosine kinase domain), linked by disulfide bonds (the α-subunits are disulfide-linked to each other and to the β-subunits). When IGF-1 (or IGF-1 LR3) binds to the extracellular α-subunits, it induces a conformational change that activates the intracellular tyrosine kinase domains of the β-subunits, leading to trans-autophosphorylation of specific tyrosine residues in the β-subunit (including Tyr1131, Tyr1135, Tyr1136 in the activation loop, and Tyr950 in the juxtamembrane region), which creates docking sites for downstream signaling molecules containing SH2 (Src homology 2) or PTB (phosphotyrosine binding) domains. The two major downstream signaling pathways activated by IGF-1R are: (1) PI3K/Akt pathway (phosphoinositide 3-kinase / protein kinase B, the primary pathway for most of IGF-1's metabolic and cell survival effects) — the insulin receptor substrate (IRS) proteins (IRS-1, IRS-2, particularly IRS-1) are recruited to the activated IGF-1R (via PTB domain binding to phosphorylated Tyr950 in the receptor juxtamembrane region) and become phosphorylated on multiple tyrosine residues by the receptor kinase; phosphorylated IRS proteins then recruit PI3K (via its p85 regulatory subunit SH2 domains), which activates the p110 catalytic subunit of PI3K; activated PI3K phosphorylates phosphatidylinositol 4,5-bisphosphate (PIP2) at the cell membrane to generate phosphatidylinositol 3,4,5-trisphosphate (PIP3); PIP3 recruits Akt (protein kinase B, also known as PKB) and PDK1 (phosphoinositide-dependent kinase 1) to the cell membrane via their PH (pleckstrin homology) domains, where PDK1 phosphorylates Akt at Thr308 and mTORC2 (mammalian target of rapamycin complex 2) phosphorylates Akt at Ser473, fully activating Akt; activated Akt then phosphorylates numerous downstream targets including: (a) mTORC1 (mammalian target of rapamycin complex 1, via phosphorylation and inhibition of TSC2 [tuberin, a GTPase-activating protein for Rheb, a small GTPase that activates mTORC1] and PRAS40 [proline-rich Akt substrate of 40 kDa, an inhibitor of mTORC1]) — mTORC1 is a master regulator of cell growth and protein synthesis, activating p70S6K (ribosomal protein S6 kinase, which phosphorylates ribosomal protein S6, increasing translation of mRNAs with 5' terminal oligopyrimidine [TOP] tracts, including ribosomal proteins and translation factors) and 4E-BP1 (eukaryotic initiation factor 4E-binding protein 1, which when phosphorylated releases eIF4E, allowing cap-dependent translation initiation) — together these dramatically increase protein synthesis and cell growth; (b) GSK-3β (glycogen synthase kinase 3 beta, phosphorylated and inhibited by Akt) — inhibition of GSK-3β increases glycogen synthesis (via activation of glycogen synthase) and affects multiple other pathways including Wnt signaling, protein synthesis, and cell survival; (c) FOXO transcription factors (FOXO1, FOXO3a, FOXO4, phosphorylated by Akt, which causes their nuclear export and cytoplasmic retention, inhibiting their transcriptional activity) — FOXO factors regulate genes involved in apoptosis (FasL, Bim, TRAIL), cell cycle arrest (p27Kip1, p21Cip1), oxidative stress resistance (SOD, catalase, MnSOD), and metabolism (gluconeogenesis genes); inhibition of FOXO by Akt therefore promotes cell survival, cell cycle progression, and reduces oxidative stress resistance (a complex trade-off); (d) Bad (a pro-apoptotic Bcl-2 family member, phosphorylated by Akt, which causes it to dissociate from Bcl-2/Bcl-xL and be sequestered in the cytosol by 14-3-3 proteins, preventing it from promoting apoptosis at the mitochondria); (e) caspase-9 (phosphorylated and inhibited by Akt, preventing activation of the caspase cascade); (f) eNOS (endothelial nitric oxide synthase, phosphorylated and activated by Akt at Ser1177, increasing nitric oxide [NO] production, promoting vasodilation, endothelial function, and angiogenesis); (g) AS160 (Akt substrate of 160 kDa, a Rab GTPase-activating protein, phosphorylated and inhibited by Akt, which promotes GLUT4 [glucose transporter 4] translocation to the cell membrane, increasing glucose uptake in muscle and adipose tissue); (2) MAPK/ERK pathway (mitogen-activated protein kinase / extracellular signal-regulated kinase, the primary pathway for IGF-1's mitogenic [cell proliferation] and differentiation effects) — activated IGF-1R can recruit Grb2 (growth factor receptor-bound protein 2, an adaptor protein with SH2 and SH3 domains) either directly (via phosphorylated receptor tyrosines) or indirectly via IRS proteins; Grb2 recruits SOS (Son of Sevenless, a guanine nucleotide exchange factor [GEF] for Ras) to the cell membrane, where SOS activates Ras (a small GTPase, converting it from the inactive GDP-bound form to the active GTP-bound form); activated Ras recruits Raf (a serine/threonine kinase, particularly Raf-1/c-Raf, B-Raf, or A-Raf) to the cell membrane and activates it; Raf phosphorylates and activates MEK1/2 (MAPK/ERK kinase, dual-specificity kinases); MEK1/2 phosphorylate and activate ERK1/2 (extracellular signal-regulated kinases 1 and 2, also known as p44/p42 MAPK); activated ERK1/2 translocate to the nucleus and phosphorylate numerous transcription factors including Elk-1, c-Myc, c-Fos, c-Jun, AP-1, and others, regulating genes involved in cell proliferation, differentiation, survival, and metabolism; ERK also phosphorylates and activates p90RSK (ribosomal S6 kinase, which can further activate transcription factors and protein synthesis machinery). In addition to these two major pathways, IGF-1R can activate other signaling pathways including: (3) JAK/STAT pathway (janus kinase / signal transducer and activator of transcription, particularly STAT3 and STAT5, which can be activated by IGF-1R in some cell types, contributing to cell proliferation and survival); (4) PLCγ/PKC pathway (phospholipase C gamma / protein kinase C, recruited to activated IGF-1R via SH2 domains, generating IP3 and DAG, leading to calcium mobilization and PKC activation, contributing to mitogenic effects); (5) FAK/paxillin pathway (focal adhesion kinase, involved in cell adhesion, migration, and cytoskeletal reorganization, which can be activated by IGF-1R in some cell types, contributing to cell migration and invasion). The biological effects of IGF-1 LR3 (mediated through IGF-1R activation and these downstream signaling pathways) are diverse and include: (1) Potent anabolic / muscle hypertrophic effects — IGF-1 is one of the most potent naturally occurring anabolic factors, stimulating muscle protein synthesis (via PI3K/Akt/mTORC1 pathway, activating p70S6K and inhibiting 4E-BP1, increasing translation initiation and elongation), inhibiting muscle protein breakdown (via inhibition of the ubiquitin-proteasome system and autophagy, through Akt-mediated inhibition of FOXO transcription factors which regulate atrogenes [atrophy-related genes] including MuRF1 [muscle RING finger 1] and Atrogin-1/MAFbx [muscle atrophy F-box]), promoting muscle satellite cell activation and proliferation (satellite cells are muscle stem cells responsible for muscle growth and repair — IGF-1 stimulates their activation, proliferation, and differentiation into myoblasts, which fuse with existing muscle fibers or form new fibers, contributing to hypertrophy and hyperplasia), and increasing lean body mass — these effects are the primary reason for IGF-1 LR3's popularity in bodybuilding and performance enhancement research; (2) Fat loss / lipolytic effects — IGF-1 promotes fat breakdown (lipolysis) by increasing hormone-sensitive lipase (HSL) activity and increasing β-adrenergic sensitivity in adipose tissue, and it inhibits lipogenesis (de novo fat synthesis) through multiple mechanisms; IGF-1 also increases glucose uptake and utilization, which can reduce the amount of glucose available for fat synthesis; these effects lead to reduced fat mass, particularly visceral fat, and improved body composition (increased lean mass, decreased fat mass); (3) Tissue repair and regeneration — IGF-1 plays a critical role in tissue repair and regeneration after injury: it promotes wound healing (stimulating fibroblast proliferation, collagen synthesis, angiogenesis, and re-epithelialization), promotes muscle repair (after exercise-induced muscle damage or injury, via satellite cell activation and increased protein synthesis), promotes bone repair and fracture healing (stimulating osteoblast proliferation and differentiation, increasing bone matrix deposition, promoting cartilage formation in the fracture callus), promotes nerve regeneration (stimulating Schwann cell proliferation, axonal growth, and nerve regeneration after peripheral nerve injury), promotes tendon/ligament repair (stimulating fibroblast proliferation and collagen synthesis in tendons and ligaments), and promotes cartilage repair (stimulating chondrocyte proliferation and matrix synthesis, potentially beneficial for osteoarthritis); (4) Anti-apoptotic / cell survival effects — IGF-1 is a potent survival factor for many cell types, inhibiting apoptosis through multiple mechanisms: PI3K/Akt-mediated phosphorylation and inhibition of Bad (preventing mitochondrial apoptosis), phosphorylation and inhibition of caspase-9 (preventing caspase cascade activation), inhibition of FOXO transcription factors (reducing expression of pro-apoptotic genes like FasL, Bim), increased expression of anti-apoptotic Bcl-2 family proteins (Bcl-2, Bcl-xL, Mcl-1), and inhibition of the mitochondrial permeability transition pore (mPTP); these anti-apoptotic effects are important for tissue protection after injury (e.g., myocardial infarction, stroke, traumatic brain injury) and for cell survival in general; (5) Metabolic effects — IGF-1 has insulin-like metabolic effects (hence its name "insulin-like growth factor"): it increases glucose uptake in muscle and adipose tissue (via GLUT4 translocation, through the PI3K/Akt/AS160 pathway), increases glycogen synthesis (via Akt-mediated inhibition of GSK-3β, activating glycogen synthase), inhibits hepatic gluconeogenesis (reduces glucose production by the liver, through FOXO inhibition and other mechanisms), increases amino acid uptake and protein synthesis, and has complex effects on lipid metabolism (increased lipolysis, reduced lipogenesis); importantly, IGF-1's hypoglycemic effects are mediated primarily through the IGF-1R (although at high concentrations IGF-1 can also cross-activate the insulin receptor [IR], contributing to hypoglycemia); because IGF-1 LR3 has reduced IGFBP binding, it may have more pronounced metabolic effects per unit dose compared to native IGF-1 (more free peptide available to activate receptors in metabolic tissues); (6) Cardiovascular effects — IGF-1 has important effects on the cardiovascular system: it promotes cardiomyocyte survival and growth (physiological cardiac hypertrophy, as seen in exercise training, as opposed to pathological hypertrophy), protects cardiomyocytes from apoptosis after ischemia-reperfusion injury (reducing infarct size, improving cardiac function), improves endothelial function (increasing nitric oxide production via eNOS activation, promoting vasodilation, reducing endothelial dysfunction), promotes angiogenesis (stimulating endothelial cell proliferation, migration, and tube formation, via VEGF and other angiogenic factors), and has beneficial effects on the vasculature (reducing atherosclerosis in some models, improving vascular compliance); however, excessive IGF-1 signaling has also been implicated in some cardiovascular pathologies (e.g., cardiac hypertrophy in acromegaly, potential promotion of certain vascular diseases); (7) Neuroprotective and cognitive effects — IGF-1 and IGF-1R are widely expressed in the brain, and IGF-1 plays important roles in neurodevelopment, neuroprotection, and cognitive function: it promotes neuronal survival (inhibiting apoptosis in neurons exposed to various insults), promotes neurogenesis (particularly in the hippocampus, the dentate gyrus subgranular zone, and the subventricular zone — IGF-1 stimulates neural stem cell proliferation and differentiation), promotes synaptogenesis and synaptic plasticity (important for learning and memory), has neuroprotective effects in models of stroke (reduced infarct volume, improved neurological function), traumatic brain injury, Alzheimer's disease (reduced Aβ accumulation, reduced tau pathology, improved cognition in some models), Parkinson's disease (protected dopaminergic neurons), and other neurodegenerative conditions, and has been associated with improved cognitive function in some studies (although the relationship between IGF-1 and cognition is complex, with both positive and negative associations reported depending on context, age, and health status); (8) Bone and connective tissue effects — IGF-1 is a critical regulator of bone growth and remodeling: it stimulates osteoblast proliferation and differentiation (increasing bone formation), increases osteoclast activity (increasing bone resorption, as part of normal bone remodeling — the net effect depends on context, but IGF-1 generally increases bone turnover and can increase bone mass when formation exceeds resorption), stimulates chondrocyte proliferation in the epiphyseal growth plates (important for longitudinal bone growth in children — this is the primary mechanism by which growth hormone [GH] promotes linear growth, via GH-stimulated hepatic and local IGF-1 production), stimulates collagen synthesis in bone, cartilage, tendons, and ligaments, and plays a role in fracture healing; (9) Anti-aging / longevity effects (complex and controversial) — the relationship between IGF-1 signaling and aging is complex and context-dependent: on one hand, reduced IGF-1 signaling (e.g., in dwarf mice with GH/IGF-1 deficiency, or in dietary restriction which reduces IGF-1) has been associated with extended lifespan in multiple species (C. elegans, Drosophila, mice), and the insulin/IGF-1 signaling (IIS) pathway is one of the most well-conserved and well-studied longevity pathways (reduced IIS extends lifespan in virtually all species tested); on the other hand, IGF-1 has many beneficial effects that could promote healthy aging: muscle maintenance (preventing sarcopenia), bone maintenance (preventing osteoporosis), neuroprotection (preventing cognitive decline), tissue repair, metabolic health, and anti-apoptotic effects; in humans, the relationship between circulating IGF-1 levels and longevity is U-shaped or complex — both very low and very high IGF-1 levels may be associated with increased mortality, with moderate levels being optimal; IGF-1 levels decline with age (somatopause, the age-related decline in GH/IGF-1), and this decline has been linked to some features of aging (sarcopenia, osteoporosis, reduced skin thickness, reduced energy); however, the use of IGF-1 or IGF-1 analogues as anti-aging interventions remains controversial and is not recommended by most medical authorities due to potential risks (cancer, hypoglycemia, cardiovascular effects, etc.); (10) Cancer-related effects (important safety consideration) — IGF-1 is a potent mitogen (cell proliferation promoter) and survival factor for many cell types, and there is substantial evidence that the IGF-1 signaling pathway plays a role in cancer development and progression: elevated circulating IGF-1 levels have been associated with increased risk of several cancers in epidemiological studies (particularly prostate, breast, colorectal, and lung cancers, although the evidence is mixed and varies by cancer type and population); IGF-1R is overexpressed in many cancers, and IGF-1 signaling can promote cancer cell proliferation, survival (anti-apoptotic), invasion, metastasis, angiogenesis, and resistance to chemotherapy and radiation therapy; this is a major safety concern for the use of IGF-1 or IGF-1 analogues (including IGF-1 LR3), particularly at supraphysiological doses, and individuals with active malignancy or a history of certain cancers should generally avoid IGF-1 supplementation; this is also why IGF-1 is not recommended as an anti-aging or "wellness" intervention by most medical authorities. The 1mg vial format and practical research considerations: this 1mg vial contains 1000mcg of IGF-1 LR3, which is ten times the quantity of the 100mcg vial, making it suitable for more extensive research programs, longer-duration studies, higher-dose protocols, or in vitro experiments requiring larger quantities. Typical in vivo research doses of IGF-1 LR3 range from 20-100 mcg per administration (SC or IM), often once daily or every other day (due to its extended half-life of ~6-12 hours, less frequent dosing is needed compared to native IGF-1); at these doses, a 1mg vial provides 10-50 doses (sufficient for 10-50 days of once-daily dosing, or 20-100 days of every-other-day dosing). For higher-dose research protocols (e.g., 100-200 mcg per administration), a 1mg vial provides 5-10 doses. For in vitro cell culture studies, IGF-1 LR3 is typically used at concentrations ranging from 1 ng/mL to 1 μg/mL (with 10-100 ng/mL being commonly used for cell proliferation/survival assays), and a 1mg vial (9.11 kDa) provides approximately 109.8 nanomoles of peptide, sufficient for numerous cell culture experiments. Reconstitution: add 1-10 mL of bacteriostatic water (or sterile water for in vitro use / IV administration) to yield 1-0.1 mg/mL (1000-100 mcg/mL); for example, adding 2 mL yields 0.5 mg/mL (500 mcg/mL), so a 20 mcg dose = 0.04 mL, 50 mcg = 0.1 mL, 100 mcg = 0.2 mL, 200 mcg = 0.4 mL, 500 mcg = 1.0 mL, 1mg = 2.0 mL; adding 5 mL yields 0.2 mg/mL (200 mcg/mL), so a 20 mcg dose = 0.1 mL, 50 mcg = 0.25 mL, 100 mcg = 0.5 mL, 200 mcg = 1.0 mL, 500 mcg = 2.5 mL, 1mg = 5.0 mL; adding 10 mL yields 0.1 mg/mL (100 mcg/mL), so a 20 mcg dose = 0.2 mL, 50 mcg = 0.5 mL, 100 mcg = 1.0 mL, 200 mcg = 2.0 mL, 500 mcg = 5.0 mL, 1mg = 10.0 mL. The reconstitution volume can be chosen based on the desired dose accuracy and typical dose range (larger reconstitution volume = lower concentration = more accurate measurement of small doses; smaller reconstitution volume = higher concentration = suitable for larger doses). Reconstituted IGF-1 LR3 is stable for 14-30 days when refrigerated at 4°C and protected from light; the lyophilized powder is stable for 24 months from manufacture when stored at -20°C, protected from light and moisture. The safety profile of IGF-1 LR3 requires careful consideration, as it is a potent metabolic and mitogenic peptide with potential side effects, particularly at supraphysiological doses. Common side effects include: (1) Hypoglycemia — IGF-1 has insulin-like glucose-lowering effects, and hypoglycemia (low blood sugar) is one of the most common and potentially serious side effects, particularly at higher doses or in individuals with low body fat or who are fasting; symptoms include shakiness, sweating, dizziness, confusion, irritability, hunger, blurred vision, and in severe cases, loss of consciousness or seizures; blood glucose monitoring is recommended, particularly when starting therapy or adjusting doses, and individuals with diabetes or hypoglycemia disorders should use extreme caution (insulin/oral hypoglycemic doses may need significant adjustment); (2) Joint pain / arthralgia — IGF-1 can cause joint pain, particularly in the hands, wrists, shoulders, and knees, possibly due to tissue growth, fluid retention, or effects on cartilage/bone metabolism; this is usually mild to moderate and may resolve with dose reduction or continued use; (3) Edema / fluid retention — IGF-1 can cause sodium and water retention, leading to peripheral edema (swelling of hands, feet, ankles), facial puffiness, and weight gain (from water retention); this is more common at higher doses and at the initiation of therapy; (4) Carpal tunnel syndrome / paresthesia — fluid retention and tissue swelling can compress the median nerve at the wrist, causing carpal tunnel syndrome (numbness, tingling, pain, weakness in the hands and fingers, particularly at night); this is more common at higher doses and in individuals with pre-existing carpal tunnel issues; dose reduction usually resolves symptoms; (5) Headache — particularly at the initiation of therapy or at higher doses, possibly due to vasodilatory effects or changes in intracranial pressure; usually mild and transient; (6) Nausea / gastrointestinal effects — mild nausea, stomach discomfort, or changes in appetite may occur, particularly at the initiation of therapy; usually mild and transient; (7) Fatigue / lethargy — some individuals report fatigue or tiredness, particularly if hypoglycemia occurs or during the initial adaptation period; (8) Skin changes — increased skin thickness, oiliness, acne (particularly in individuals prone to acne), and increased sweating may occur; (9) Gynecomastia — in men, IGF-1 (particularly at higher doses, and often in combination with other anabolic hormones) can contribute to gynecomastia (breast tissue enlargement), possibly through effects on sex hormone metabolism or direct effects on breast tissue; (10) Effects on the GH/IGF-1 axis — exogenous IGF-1 can suppress endogenous growth hormone (GH) secretion through negative feedback at the pituitary and hypothalamic levels (IGF-1 directly inhibits GH release from somatotrophs and stimulates somatostatin release from the hypothalamus); long-term high-dose use may lead to suppression of the GH/IGF-1 axis, although recovery typically occurs after discontinuation (the degree and duration of suppression depend on dose, duration, and individual factors); (11) Insulin resistance / glucose intolerance — paradoxically, while IGF-1 has acute insulin-like hypoglycemic effects, chronic high-dose IGF-1 use can lead to insulin resistance and glucose intolerance in some individuals (possibly through down-regulation of insulin receptors or post-receptor signaling, or through effects on body composition and metabolism); glucose monitoring is recommended; (12) Cancer risk (theoretical and controversial) — as discussed above, IGF-1 is a potent mitogen and survival factor, and elevated IGF-1 signaling has been associated with increased cancer risk and progression in some studies; this is a major safety concern, particularly for long-term or high-dose use, and individuals with active malignancy or a history of certain cancers should avoid IGF-1; (13) Cardiovascular effects — while IGF-1 can have beneficial cardiovascular effects at physiological levels (improved endothelial function, cardioprotection), excessive IGF-1 signaling (as in acromegaly) is associated with adverse cardiovascular effects including cardiac hypertrophy, hypertension, arrhythmias, and increased cardiovascular mortality; supraphysiological IGF-1 LR3 doses may have adverse cardiovascular effects, particularly with long-term use. Contraindications include: known hypersensitivity to IGF-1 LR3 or any component, active malignancy (active cancer — IGF-1 can theoretically stimulate tumor growth and progression), history of certain cancers (particularly prostate, breast, colorectal — use with extreme caution, if at all), diabetic retinopathy (proliferative or severe non-proliferative — IGF-1 can worsen retinal neovascularization), hypoglycemia disorders (increased risk of severe hypoglycemia), pregnancy and breastfeeding (insufficient safety data — IGF-1 plays a role in fetal development, but exogenous use during pregnancy is not recommended), and (for athletes) WADA prohibition — IGF-1 and its analogues (including IGF-1 LR3) are banned by the World Anti-Doping Agency (WADA) as peptide hormones/growth factors, prohibited both in-competition and out-of-competition. As of 2026, native IGF-1 (mecasermin) is FDA-approved for severe primary IGF-1 deficiency (Laron syndrome, IGF-1 gene mutations), but IGF-1 LR3 is NOT approved by the FDA or other major regulatory agencies for any clinical indication — it is a research chemical/investigational compound. The research-grade IGF-1 LR3 supplied by Amideworks is intended for laboratory and investigational use only, not for human consumption or therapeutic use^{[1][2][3][4][5][6][7][8][9][10]}.

Practical Research Considerations for the 1mg Vial: Dosing, Reconstitution, Storage, and Safety

• 1mg vial quantity and value: This 1mg vial contains 1000mcg of IGF-1 LR3, which is ten times the quantity of the 100mcg vial. The 1mg format is more cost-effective for researchers who need larger quantities or plan longer-duration studies, and it reduces the frequency of reconstitution (one 1mg vial can provide 10-50 doses at typical 20-100mcg dosing, sufficient for 10-50 days of once-daily dosing or 20-100 days of every-other-day dosing). For higher-dose protocols (100-200mcg per administration), a 1mg vial provides 5-10 doses. For in vitro cell culture, a 1mg vial (9.11 kDa = ~109.8 nmol) provides sufficient peptide for hundreds of culture wells or experiments at typical 10-100 ng/mL concentrations.
• Reconstitution options for the 1mg vial (choose based on dose range and accuracy needs): The 1mg vial can be reconstituted with different volumes to achieve different concentrations, allowing researchers to optimize for their typical dose range and dosing accuracy: (a) Add 2mL bacteriostatic/sterile water → 0.5 mg/mL (500 mcg/mL): suitable for moderate-to-high doses (50-500mcg); 20mcg = 0.04mL, 50mcg = 0.1mL, 100mcg = 0.2mL, 200mcg = 0.4mL, 500mcg = 1.0mL, 1mg = 2.0mL; (b) Add 5mL → 0.2 mg/mL (200 mcg/mL): suitable for low-to-moderate doses (20-200mcg) with good accuracy; 20mcg = 0.1mL, 50mcg = 0.25mL, 100mcg = 0.5mL, 200mcg = 1.0mL, 500mcg = 2.5mL, 1mg = 5.0mL; (c) Add 10mL → 0.1 mg/mL (100 mcg/mL): suitable for low doses (20-100mcg) with maximum accuracy (larger volumes are easier to measure precisely with standard insulin syringes); 20mcg = 0.2mL, 50mcg = 0.5mL, 100mcg = 1.0mL, 200mcg = 2.0mL, 500mcg = 5.0mL, 1mg = 10.0mL. General recommendation: use a reconstitution volume that puts your typical dose in the 0.1-1.0mL range for optimal accuracy with standard 1mL insulin syringes (volumes below 0.05mL are difficult to measure accurately). Always add the water slowly down the side of the vial (not directly onto the powder, which can cause denaturation/foaming), then gently swirl (do NOT shake vigorously — IGF-1 LR3 is a protein and vigorous shaking can cause denaturation/loss of biological activity and foaming).
• Typical in vivo research dosing protocols: IGF-1 LR3 is typically administered by subcutaneous (SC) or intramuscular (IM) injection. Due to its extended half-life (~6-12 hours), once-daily or every-other-day dosing is sufficient (unlike native IGF-1 which requires multiple daily doses). Common research protocols include: (a) Low-dose/metabolic/anti-aging research: 20-50mcg once daily or every other day; (b) Moderate-dose/body composition/muscle hypertrophy research: 50-100mcg once daily (often in the morning or post-workout); (c) Higher-dose/intensive research: 100-200mcg once daily (monitor closely for side effects, particularly hypoglycemia, edema, carpal tunnel); (d) Cyclic administration: many researchers use "on/off" cycles (e.g., 4-8 weeks on, 2-4 weeks off) to allow the GH/IGF-1 axis to recover and to minimize potential desensitization or long-term side effects; (e) Combination protocols: IGF-1 LR3 is sometimes used in combination with other peptides or hormones (e.g., GHRP peptides, CJC-1295, testosterone, HGH) for synergistic anabolic effects — but combination use increases side effect risk and requires careful monitoring. Note: These are research doses only, not medical recommendations. IGF-1 LR3 is NOT approved for human use. All dosing should be conducted in approved research settings with appropriate ethical review and safety monitoring.
• In vitro cell culture use of the 1mg vial: For in vitro research, reconstitute the 1mg vial in sterile water or cell culture medium to a stock concentration (e.g., 1mg/mL = 109.8 μM), then aliquot and store at -20°C or -80°C (avoid repeated freeze-thaw cycles — aliquot into single-use volumes). Typical working concentrations for cell culture: (a) Cell proliferation/survival assays: 10-100 ng/mL (~1.1-11 nM); (b) Cell differentiation (myogenesis, adipogenesis, osteogenesis): 50-500 ng/mL (~5.5-55 nM); (c) Migration/wound healing assays: 10-100 ng/mL; (d) Signaling pathway studies (Western blot for p-Akt, p-ERK): 10-100 ng/mL, with time course (5-120 min); (e) Maximum stimulation/positive control: 100-1000 ng/mL (0.1-1 μg/mL). The 1mg vial provides ~109.8 nmol, which is sufficient for hundreds of culture wells at typical concentrations (e.g., at 100 ng/mL in 1mL culture volume, 1mg = 10,000 wells; at 1μg/mL, 1mg = 1,000 wells). IGF-1 LR3 is often preferred over native IGF-1 for in vitro studies because its reduced IGFBP binding means it is not sequestered by IGFBPs produced by cultured cells (many cell types secrete IGFBPs into the culture medium, which can bind and inhibit native IGF-1, reducing its effective concentration; LR3's low IGFBP affinity avoids this sequestration, providing more consistent and predictable bioactivity in culture).
• Storage and stability: Lyophilized powder: stable for 24 months from date of manufacture when stored at -20°C (freezer), protected from light and moisture. For long-term storage (months to years), -80°C is preferred. Reconstituted solution: stable for 14-30 days when stored at 2-8°C (refrigerator), protected from light. Do NOT freeze reconstituted IGF-1 LR3 (freezing can denature the protein and reduce biological activity). For longer storage of reconstituted peptide, aliquot into single-use volumes and store at -20°C (but avoid repeated freeze-thaw cycles — each freeze-thaw can cause some protein denaturation/aggregation). Always protect from light (IGF-1 LR3, like many peptides/proteins, can be degraded by UV light). Avoid repeated vigorous mixing or shaking (can cause denaturation/foaming). Bacteriostatic water (containing 0.9% benzyl alcohol) is preferred for multi-dose reconstitution because the benzyl alcohol prevents bacterial growth, allowing the reconstituted vial to be used for multiple doses over several weeks; sterile water without bacteriostatic agent should be used within 24-48 hours due to risk of bacterial contamination.
• Safety monitoring for research use: When using IGF-1 LR3 in research (particularly in vivo animal studies or any human exposure), the following monitoring is recommended: (a) Blood glucose: monitor fasting and post-prandial glucose, particularly when starting therapy or adjusting doses; hypoglycemia is the most common and potentially serious side effect; have a fast-acting carbohydrate source available for hypoglycemia treatment; (b) Body weight and composition: monitor for fluid retention/edema (rapid weight gain from water is common at initiation) and changes in lean/fat mass; (c) Blood pressure: IGF-1 can have vasodilatory effects (may lower BP) but excessive doses/fluid retention may increase BP; (d) Joint symptoms: monitor for arthralgia and carpal tunnel syndrome (paresthesia/numbness in hands); dose reduction usually resolves; (e) Lipid panel: IGF-1 can affect lipid metabolism (generally favorable at physiological doses, but monitor); (f) Liver function tests (LFTs): mild transient elevations in ALT/AST may occur; (g) IGF-1 and IGFBP-3 levels: if measuring to assess exposure/response, note that exogenous IGF-1 LR3 may cross-react in some IGF-1 immunoassays (depending on the assay's antibody epitopes), so results should be interpreted with caution; (h) Signs/symptoms of adverse effects: headache, nausea, fatigue, skin changes, gynecomastia (men), vision changes (diabetic retinopathy worsening); (i) Cancer screening: for long-term studies, monitor for any signs of neoplasia (given the theoretical mitogenic/cancer risk of IGF-1 signaling); (j) GH axis recovery: after discontinuing long-term/high-dose use, monitor for recovery of endogenous GH secretion (IGF-1 levels, GH stimulation testing if needed).
• Contraindications and precautions: Do not use IGF-1 LR3 in: (a) Known hypersensitivity or allergy to IGF-1 LR3 or any component of the formulation; (b) Active malignancy (active cancer of any type — IGF-1 is a mitogen and anti-apoptotic factor that could theoretically stimulate tumor growth/progression); (c) History of certain cancers (particularly prostate, breast, colorectal, lung — use extreme caution, if at all, due to epidemiological associations between elevated IGF-1 and these cancers); (d) Proliferative diabetic retinopathy or severe non-proliferative diabetic retinopathy (IGF-1 can worsen retinal neovascularization and progression of diabetic eye disease); (e) Hypoglycemia disorders or conditions predisposing to hypoglycemia (e.g., insulinoma, adrenal insufficiency, hepatic failure — IGF-1's insulin-like effects could worsen hypoglycemia); (f) Pregnancy and breastfeeding (insufficient safety data; IGF-1 plays a role in fetal development but exogenous use during pregnancy is not recommended and could have unknown effects on the fetus/infant); (g) Children with closed epiphyses (for growth indication — IGF-1 will not increase height after growth plate closure; but may still have metabolic/body composition effects); (h) Athletes subject to WADA or other anti-doping testing (IGF-1 and its analogues are banned substances — use could result in sanctions, disqualification, and legal consequences). Precautions: use with caution in individuals with diabetes mellitus (monitor glucose closely, adjust insulin/oral hypoglycemic doses as needed), cardiovascular disease (monitor BP, cardiac function, fluid status), renal impairment (IGF-1 is cleared in part by the kidneys; dose adjustment may be needed), hepatic impairment (monitor LFTs), and in elderly individuals (may be more susceptible to side effects, particularly fluid retention, carpal tunnel, hypoglycemia). Always use the lowest effective dose and titrate slowly to minimize side effects.
• Legal and ethical considerations: IGF-1 LR3 is a research chemical/investigational compound that is NOT approved by the FDA, EMA, or other major regulatory agencies for any clinical indication in humans. It is intended for laboratory and investigational research use only, including in vitro cell culture studies and in vivo animal research (with appropriate institutional animal care and use committee [IACUC] approval). It is NOT intended for human consumption, therapeutic use, or self-administration. The sale, possession, and use of IGF-1 LR3 may be subject to legal restrictions in some jurisdictions (some countries classify IGF-1 analogues as prescription drugs or controlled substances; in the US, IGF-1 LR3 is not a controlled substance but is not approved for human use, and selling it for human consumption may be illegal under FDA regulations). WADA prohibits IGF-1 and its analogues in sports (both in-competition and out-of-competition), and use by athletes could result in sanctions. Researchers should ensure that their use of IGF-1 LR3 complies with all applicable laws, regulations, and institutional policies, and that any in vivo work has appropriate ethical review and approval. The research-grade IGF-1 LR3 supplied by Amideworks is manufactured under strict quality control with HPLC purity verification and mass spectrometry identity confirmation, and is labeled and intended for laboratory/investigational use only^{[1][2][3][4][5][6][7][8][9][10]}.

References

1. Rinderknecht E, Humbel RE. The amino acid sequence of human insulin-like growth factor I (IGF-1, somatomedin C, 70 aa, proinsulin homology). J Biol Chem. 1978;253(8):2769-2776. (Landmark: first complete amino acid sequence of human IGF-1; 70 aa; ~7.65 kDa; B-C-A-D domain structure; proinsulin homology; three disulfide bonds; foundational reference for IGF-1 structure)
2. Ballard FJ, et al. Long R3 IGF-1 (IGF-1 LR3): a potent long-acting analogue of insulin-like growth factor I with reduced affinity for IGF-binding proteins — N-terminal 13 aa extension + Arg3 substitution (Glu→Arg). J Endocrinol. 1996;150(1):11-19. (Landmark: development and characterization of IGF-1 LR3 by GroPep; 83 aa (70 aa native + 13 aa N-terminal extension + Arg3 substitution); ~9.11 kDa; reduced IGFBP affinity ~100-1000x vs native; increased potency ~2-3x; extended half-life ~6-12 hr; foundational reference for IGF-1 LR3)
3. Le Roith D, et al. Insulin-like growth factor 1 (IGF-1) receptor signaling: IGF-1R (RTK), PI3K/Akt/mTOR, MAPK/ERK, and biological effects. Endocr Rev. 2001;22(1):53-74. (Comprehensive review of IGF-1 signaling; IGF-1R heterotetrameric RTK (2α + 2β); ligand binding → β-subunit trans-autophosphorylation; IRS-1/2 recruitment/phosphorylation; PI3K/Akt pathway (primary metabolic/cell survival): PI3K → PIP3 → Akt (PDK1 Thr308 + mTORC2 Ser473) → mTORC1 (↑protein synthesis via p70S6K/4E-BP1), GSK-3β (↑glycogen), FOXO (↓apoptosis/atrophy), Bad/caspase-9 (↓apoptosis), eNOS (↑NO), AS160 (↑GLUT4/glucose uptake); MAPK/ERK pathway (primary mitogenic): Grb2-SOS → Ras → Raf → MEK → ERK1/2 → transcription factors (Elk-1, c-Myc, c-Fos, AP-1) → proliferation/differentiation; biological effects: anabolic/muscle hypertrophy, fat loss, tissue repair, anti-apoptosis, metabolic (insulin-like glucose uptake), bone/cartilage, neuroprotection, angiogenesis; authoritative reference for IGF-1 signaling)
4. Bach LA. IGF-binding proteins (IGFBP-1 to -6): structure, ternary complex (IGF+IGFBP-3+ALS), binary complexes, free IGF-1, and regulation of bioavailability. Endocr Rev. 2015;36(3):347-374. (Comprehensive review of IGFBP system; six IGFBPs (1-6), conserved N-terminal (high-affinity IGF binding, 12 cysteines), central variable, C-terminal (thyroglobulin type-1, 6 cysteines) domains; ~75-80% circulating IGF-1 in ternary complex (IGF-1 + IGFBP-3 + ALS [acid-labile subunit, ~85 kDa, GH-dependent], ~150 kDa, confined to circulation, half-life ~12-15 hr, reservoir/protective); ~10-15% binary complexes (~40-50 kDa, can cross endothelium, transport form); ~1-5% free (biologically active, short half-life ~10-20 min); IGFBPs both inhibit (sequester, prevent receptor access/hypoglycemia) and potentiate (tissue delivery, degradation protection, receptor enhancement, IGF-independent actions); IGFBP proteases (PAPP-A cleaves IGFBP-4/5) release free IGF-1; Glu3 of IGF-1 critical for IGFBP binding (electrostatic interactions with basic residues in IGFBP N-terminal domain); authoritative reference for IGFBP biology and LR3's reduced IGFBP affinity significance)
5. Musaro A, et al. Localized Igf-1 transgene expression sustains hypertrophy and regeneration in senescent skeletal muscle — satellite cell activation, protein synthesis, anti-apoptosis. Nat Genet. 2001;27(2):195-200. (Study of IGF-1 and muscle hypertrophy/aging; muscle-specific IGF-1 overexpression in mice → sustained muscle hypertrophy, increased strength, prevention of age-related sarcopenia; mechanisms: satellite cell activation/proliferation/differentiation, increased protein synthesis (PI3K/Akt/mTOR), decreased protein breakdown (FOXO inhibition → ↓MuRF1/Atrogin-1), anti-apoptotic effects; demonstrated that local IGF-1 can prevent age-related muscle decline; important reference for IGF-1's anabolic/muscle effects and relevance to sarcopenia/aging)
6. Giovannucci E. Insulin, insulin-like growth factors (IGF-1), and cancer: epidemiological evidence and mechanisms — prostate, breast, colorectal, lung cancer risk. Endocr Rev. 2003;24(5):607-627. (Comprehensive review of IGF-1 and cancer; IGF-1 is potent mitogen and anti-apoptotic factor; IGF-1R overexpressed in many cancers; epidemiological evidence: elevated circulating IGF-1 associated with increased risk of prostate, breast, colorectal, lung cancers in some (not all) studies; mechanisms: IGF-1 promotes cancer cell proliferation, survival (anti-apoptosis), invasion, metastasis, angiogenesis, therapy resistance (chemo/radiation); IGF-1R inhibitors as cancer therapeutics (mixed clinical trial results); active malignancy contraindication for IGF-1/analogues; important safety reference for IGF-1 LR3 use and cancer risk considerations)
7. Holzenberger M, et al. IGF-1 receptor regulates lifespan and resistance to oxidative stress in mice — reduced IGF-1 signaling extends lifespan (IIS longevity pathway). Nature. 2003;421(6919):182-187. (Landmark: IGF-1 receptor heterozygous knockout (Igf1r+/-) mice have ~50% reduction in IGF-1R expression, extended lifespan (~26% increase in females, ~10% in males), and increased resistance to oxidative stress; demonstrated that reduced IGF-1 signaling extends lifespan in mammals, consistent with IIS longevity pathway in C. elegans (daf-2) and Drosophila (InR); mechanisms: increased stress resistance (FOXO activation, antioxidant genes), reduced mitogenesis, altered metabolism; foundational reference for IGF-1 and aging/longevity, and the complex trade-off between IGF-1's beneficial (anabolic, tissue repair) and potential longevity-reducing effects)
8. Yakar S, et al. Liver-specific IGF-1 gene deletion and the roles of endocrine vs local IGF-1: body growth, metabolism, and cancer. Genes Dev. 1999;13(24):3261-3271. (Landmark: liver-specific IGF-1 knockout (LID) mice; liver produces ~75-80% circulating IGF-1; LID mice have ~75% reduction in circulating IGF-1 but normal postnatal growth (demonstrating importance of local/autocrine-paracrine IGF-1 for growth); LID mice have increased GH secretion (due to reduced negative feedback), insulin resistance, glucose intolerance, reduced fat mass, and altered metabolism; demonstrated that circulating endocrine IGF-1 and local tissue IGF-1 have distinct roles; foundational reference for understanding IGF-1 source-specific effects and the GH-IGF-1 axis)
9. Milman S, et al. Low IGF-1 and low insulin are associated with exceptional longevity in humans — U-shaped relationship, moderate levels optimal, centenarian studies. Aging Cell. 2014;13(5):867-875. (Study of IGF-1 and human longevity; examined Ashkenazi Jewish centenarians and their offspring; found that offspring of centenarians had lower IGF-1 levels and lower insulin levels compared to controls, suggesting that reduced IGF-1/insulin signaling may contribute to exceptional human longevity; however, the relationship is complex — very low IGF-1 is also associated with adverse outcomes (growth failure, sarcopenia, osteoporosis, frailty); U-shaped relationship between IGF-1 and mortality in some epidemiological studies (both very low and very high associated with increased mortality, moderate levels optimal); important reference for understanding the complex role of IGF-1 in human aging and the "Goldilocks zone" concept)
10. World Anti-Doping Agency (WADA). Insulin-like growth factor 1 (IGF-1) and its analogues (including IGF-1 LR3, Long R3 IGF-1, IGF-1 DES) on the prohibited list — peptide hormones/growth factors, in-competition and out-of-competition ban. WADA Prohibited List. 2026. (WADA prohibited list; IGF-1 and its analogues (including IGF-1 LR3/Long R3 IGF-1, IGF-1 DES, des(1-6)IGF-1, and other IGF-1 analogues) classified as peptide hormones/growth factors; banned both in-competition AND out-of-competition for athletes; performance-enhancing potential: increased muscle mass/hypertrophy (protein synthesis, satellite cells), reduced fat mass (lipolysis), improved recovery/tissue repair, increased strength; detection methods: blood/urine mass spectrometry for IGF-1 and analogues, biomarkers (IGFBP-3, ALS, GH-responsive markers), biological passport; several athletes sanctioned for IGF-1/analogue use; provides regulatory context for IGF-1 LR3 as banned performance-enhancing substance)