IGF-1 (insulin-like growth factor 1)

IGF-1 — insulin-like growth factor 1, also called somatomedin C — is the principal mediator of growth hormone’s anabolic and growth-promoting effects in peripheral tissues. Hepatic IGF-1 synthesis downstream of GHR activation is the canonical readout in growth-hormone-axis pharmacology research.

Definition

IGF-1 is a 70-amino-acid single-chain polypeptide with structural homology to proinsulin. The compound is synthesised predominantly by hepatocytes in response to growth hormone signalling through the GH receptor, secreted into circulation bound to IGF-binding proteins (principally IGFBP-3), and delivered to peripheral tissues where it engages the IGF-1 receptor (IGF-1R) — a receptor tyrosine kinase structurally related to the insulin receptor. Activation of IGF-1R drives downstream PI3K-Akt-mTOR and Ras-MAPK signalling, mediating the anabolic, mitogenic, and growth-promoting effects historically attributed to growth hormone itself.

The relationship between GH and IGF-1 is the central axis of growth-hormone-axis pharmacology research. GHRH analogues and growth hormone secretagogues are characterised primarily by their ability to increase endogenous GH release from the pituitary; the downstream rise in serum IGF-1 is the secondary biomarker that quantifies whether the change in GH release translated into peripheral-tissue signalling. The GH/IGF-1 axis terminology in the published literature refers to this coupled signalling architecture.

How IGF-1 is studied in peptide research

Serum IGF-1 levels are the standard biomarker readout for GHRH-analogue and GH-secretagogue research. The Teichman characterisation of CJC-1295 in healthy adults documented prolonged stimulation of both GH and IGF-1 secretion as the canonical pharmacological signature of the long-acting GHRH analogue (PMID 16352683). The Sackmann-Sala work documented serum protein profile changes during sustained GH/IGF-1 axis activation by CJC-1295 (PMID 19386527). The Alba GHRH-knockout mouse model established that CJC-1295 normalises growth specifically through reconstitution of GHRH-receptor signalling (PMID 16822960). The Sattler review consolidates the GH/IGF-1 axis biology in the aging-male context (PMID 24054930).

IGF-1R signalling is also implicated in tissue-repair research independently of pituitary GH release. The BPC-157 tendon-fibroblast work documented growth hormone receptor up-regulation alongside the tissue-repair findings (PMID 21030672), with downstream IGF-1-axis engagement as a plausible mediator of the observed cellular phenotypes.

Related terms

• Growth hormone receptor
• Akt signalling
• mTOR
• Tyrosine kinase receptor
• IGF-1 receptor (IGF-1R)
• IGFBP-3 / IGF-binding protein 3
• Somatomedin C

Compounds where IGF-1 appears in the mechanism literature

• CJC-1295 No DAC — long-acting GHRH analogue; IGF-1 elevation is the canonical downstream biomarker
• Tesamorelin — GHRH analogue; IGF-1 normalization is a secondary clinical endpoint in HIV-lipodystrophy trials
• Ipamorelin — selective growth hormone secretagogue; IGF-1 elevation downstream of GH pulse
• BPC-157 — growth hormone receptor up-regulation documented in tendon-fibroblast culture with implied downstream IGF-1-axis engagement

References

1. Chang CH et al. The promoting effect of pentadecapeptide BPC 157 on tendon healing involves tendon outgrowth, cell survival, and cell migration. J Appl Physiol 2011;110(3):774-780. [PMID 21030672]
2. Teichman SL et al. Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults. J Clin Endocrinol Metab 2006;91(3):799-805. [PMID 16352683]
3. Alba M et al. Once-daily administration of CJC-1295, a long-acting growth hormone-releasing hormone (GHRH) analog, normalizes growth in the GHRH knockout mouse. Am J Physiol Endocrinol Metab 2006;291(6):E1290-E1294. [PMID 16822960]
4. Sackmann-Sala L et al. Activation of the GH/IGF-1 axis by CJC-1295, a long-acting GHRH analog, results in serum protein profile changes in normal adult subjects. Growth Horm IGF Res 2009;19(6):471-477. [PMID 19386527]
5. Sattler FR. Growth hormone in the aging male. Best Pract Res Clin Endocrinol Metab 2013;27(4):541-555. [PMID 24054930]

Glossary entries describe research-context use of peptide-research terminology. They do not constitute medical, veterinary, or clinical advice. Every compound in the Ronin catalog is sold strictly for laboratory and research use only.