IGF-1
Insulin-Like Growth Factor 1 (IGF-1) is a 70-amino acid polypeptide hormone that mediates many of the growth-promoting and anabolic effects of growth hormone throughout the body. It plays a central role in muscle development, bone formation, tissue repair, and metabolic regulation, serving as the primary downstream effector of the GH-IGF axis.
The Primary Effector of Growth Hormone Signaling
Insulin-Like Growth Factor 1 (IGF-1), also known as somatomedin C, is a 70-amino acid polypeptide with structural similarity to insulin. It is primarily produced by the liver in response to growth hormone stimulation, though virtually all tissues produce IGF-1 locally for autocrine and paracrine signaling. IGF-1 circulates in the bloodstream bound to a family of six IGF-binding proteins (IGFBPs), with IGFBP-3 being the most abundant carrier. The GH-IGF-1 axis is one of the most fundamental endocrine systems governing growth, metabolism, and tissue maintenance throughout life.
Research into IGF-1 spans decades and encompasses its roles in skeletal growth, muscle development and maintenance, neuronal survival and function, bone remodeling, wound healing, and metabolic regulation. IGF-1 levels, like GH, decline with age, and low IGF-1 states have been associated with sarcopenia (muscle loss), osteoporosis, impaired recovery, cognitive decline, and metabolic dysfunction. Recombinant IGF-1 (mecasermin) carries FDA approval for the treatment of severe primary IGF-1 deficiency. Research continues to explore its therapeutic potential across a broader range of clinical applications.
At Aspire Rejuvenation, IGF-1 therapy is available for patients whose evaluation reveals IGF-1 insufficiency that may not be adequately addressed by GH secretagogues alone. Our physicians perform comprehensive testing to assess where IGF-1 fits within the broader picture of each patient's GH-IGF axis function, determining whether direct IGF-1 support, GH stimulation, or a combination approach is most appropriate.
Proposed Mechanism of Action
IGF-1 signals primarily through the IGF-1 receptor (IGF-1R), a heterotetrameric tyrosine kinase receptor structurally related to the insulin receptor. Upon IGF-1 binding, the receptor undergoes autophosphorylation and recruits intracellular adaptor proteins, principally IRS-1 and IRS-2. These adaptors activate two major signaling branches: the PI3K/Akt pathway and the MAPK/ERK pathway. The PI3K/Akt branch is central to IGF-1's metabolic and survival effects - it promotes glucose transporter (GLUT4) translocation for glucose uptake, activates mTOR for protein synthesis, phosphorylates BAD to inhibit apoptosis, and stimulates glycogen synthesis. This pathway is the primary mediator of IGF-1's muscle-building and tissue-protective effects.
The bioavailability and activity of IGF-1 are tightly regulated by six IGF-binding proteins (IGFBP-1 through IGFBP-6). IGFBP-3 carries approximately 80% of circulating IGF-1 in a ternary complex with the acid-labile subunit (ALS), creating a reservoir that extends IGF-1's half-life from minutes to approximately 16 hours. Other IGFBPs modulate IGF-1 activity at the tissue level - some inhibit IGF-1 receptor access while others potentiate local IGF-1 activity. This complex regulatory system ensures appropriate tissue-specific IGF-1 signaling. Local IGF-1 production (autocrine/paracrine) also plays crucial roles, particularly in skeletal muscle where mechanical loading stimulates local IGF-1 splice variants (MGF/IGF-1Ec) that activate satellite cells for muscle repair and hypertrophy.
What IGF-1 Is Being Explored For
These are the primary areas where IGF-1 has been studied or discussed in the context of peptide therapy. Research depth varies by area.
How IGF-1 Is Offered
IGF-1 is available through Aspire in the following formulations, all compounded by licensed U.S. 503A pharmacies. Your clinician will recommend the appropriate form based on your goals and treatment plan.
How Treatment Works
Peptide therapy at Aspire follows a clinician-guided process. IGF-1 is not available for self-prescribing or anonymous purchase.
IGF-1 FAQ
IGF-1 has one of the most extensive evidence bases in endocrinology. Recombinant IGF-1 (mecasermin) is FDA-approved for severe primary IGF-1 deficiency. Broader applications are supported by extensive preclinical and clinical research spanning several decades.
Ready to explore IGF-1?
Talk with an Aspire clinician about your goals and whether IGF-1 therapy may be appropriate for you.
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