Glossary

IGF-1

Insulin-Like Growth Factor 1

IGF-1 is the primary downstream effector of growth hormone. When GH binds its receptors on the liver, the liver synthesizes and releases IGF-1, which then circulates and drives much of what is colloquially called ‘the GH effect’ — protein synthesis, satellite-cell activation, soft-tissue repair, and a contribution to fat oxidation.

In peptide research, IGF-1 is the canonical biomarker for GH-axis activation. Whether a researcher is dosing sermorelin, tesamorelin, ipamorelin, MK-677, or somatropin, total IGF-1 is the most commonly tracked endpoint because it integrates the cumulative pulsatile GH release over the prior 12–24 hours.

IGF-1 LR3 is a long-acting analog (Long Arg-3 IGF-1) used in research as an exogenous IGF-1 source. It has a substantially longer half-life than native IGF-1 and binds with reduced affinity to IGF-binding proteins, which is what gives it its extended duration of action.

Used in 5 research peptides

See also

Educational use only

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