Source comparison
Mechanism of Action: GHRH Pathway vs Ghrelin Mimicry
CJC-1295 is a synthetic analog of growth hormone-releasing hormone (GHRH). The endogenous peptide secreted by the arcuate nucleus of the hypothalamus that binds to GHRH receptors on anterior pituitary somatotrophs. The unmodified peptide (CJC-1295 without DAC,
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- CJC-1295 is a synthetic analog of growth hormone-releasing hormone (GHRH). The endogenous peptide secreted by the arcuate nucleus of the hypothalamus that binds to GHRH receptors on anterior pituitary somatotrophs. The unmodified peptide (CJC-1295 without DAC, also called Modified GRF 1-29 or Mod GRF) has a plasma half-life of approximately 30 minutes, identical to native GHRH. The DAC modification. Tetra-substituted lysine conjugation that allows covalent binding to serum albumin. Extends this half-life to 6–8 days by protecting the peptide from dipeptidyl peptidase-IV (DPP-IV) degradation. This creates a sustained GHRH signal that doesn't override the body's natural pulsatile GH release but amplifies each endogenous pulse. IGF-1 levels rise gradually and remain elevated for the duration of the half-life, which is why CJC-1295 (with DAC) is dosed once or twice weekly in research protocols rather than multiple times daily.
- Hexarelin belongs to a different class entirely: growth hormone secretagogues (GHS), which are synthetic ghrelin mimetics. Ghrelin is the endogenous 'hunger hormone' produced primarily by gastric P/D1 cells, and it binds to the growth hormone secretagogue receptor type 1a (GHS-R1a). A receptor distinct from the GHRH receptor. When Hexarelin binds GHS-R1a on pituitary somatotrophs, it triggers immediate GH release independent of GHRH signalling. Peak plasma GH occurs within 30–60 minutes post-administration, often reaching levels 10–15 times baseline, then returns to baseline within 4–6 hours. IGF-1 elevation is transient because the GH spike is brief. The practical implication: Hexarelin delivers acute, high-amplitude GH bursts suitable for protocols requiring immediate hormonal response, but it does not sustain IGF-1 the way CJC-1295 does. Our team has observed this pattern consistently across comparative pharmacokinetic studies. The CJC-1295 vs Hexarelin which better comparison ultim