Where does CJC-1295 act?

At the GHRH receptor on pituitary somatotrophs, the same receptor native GHRH uses.

Why GRF(1-29) rather than full GHRH?

Receptor-activating capacity resides in the N-terminal region; the 29-residue fragment retains full agonist activity.

Does continuous stimulation flatten GH pulses?

Ionescu and Frohman reported pulsatile GH secretion persisting during continuous stimulation, with the pituitary imposing its own rhythm.

CJC-1295 Mechanism: A GHRH Analogue

The short answer

CJC-1295 is an agonist at the growth hormone-releasing hormone receptor on pituitary somatotrophs. It is based on the active GRF(1-29) fragment of native GHRH (twenty-nine residues ending in argininamide) with four substitutions that resist enzymatic degradation, chiefly by blocking the DPP-4 cleavage site at the N-terminus.

Key facts

Receptor: GHRH receptor (GHRHR)
Location: Pituitary somatotrophs
Basis: GRF(1-29), the active GHRH fragment
Substitutions: D-Ala2, Gln8, Ala15, Leu27
Native GHRH half-life: Minutes
Normal signalling: Pulsatile

What GHRH normally does

Growth hormone-releasing hormone is produced in the hypothalamus and travels through the hypophyseal portal circulation to the anterior pituitary, where it acts on somatotrophs to stimulate GH synthesis and release. Its release is pulsatile, and the resulting GH secretion is pulsatile too, a pattern that appears to matter for downstream effects.

Why only the first 29 residues

Native GHRH is 44 residues but its receptor-activating capacity resides in the N-terminal region. GRF(1-29) retains full agonist activity, which is why sermorelin (native GRF(1-29)) was developed as a therapeutic and why CJC-1295 starts from that fragment rather than the whole hormone.

Research material referenced

CJC-1295 + Ipamorelin 5+5mg, third-party HPLC tested

Buy CJC-1295 + Ipamorelin · £36.99

What each substitution addresses

D-alanine at position 2 is the critical one: DPP-4 cleaves GHRH after residue 2, and a D-amino acid is not a substrate. Gln8, Ala15 and Leu27 address further degradation-prone points. Together they take the peptide from a half-life of minutes to roughly thirty, without altering the receptor interaction.

The pulsatility question the DAC form raises

Physiological GHRH arrives in pulses. A covalently albumin-bound analogue produces continuous receptor exposure instead, which is a different stimulus. Ionescu and Frohman addressed this in 2006, reporting that pulsatile GH secretion persists during continuous stimulation. The pituitary appears to impose its own rhythm rather than simply following the input.

Why the receptor is a good target

Acting upstream at GHRH rather than administering GH directly means the pituitary retains its own regulatory feedback. That is a meaningfully different intervention from exogenous GH, and it is the general rationale for secretagogue approaches, whichever receptor they use.

Frequently asked questions

Where does CJC-1295 act?: At the GHRH receptor on pituitary somatotrophs, the same receptor native GHRH uses.
Why GRF(1-29) rather than full GHRH?: Receptor-activating capacity resides in the N-terminal region; the 29-residue fragment retains full agonist activity.
Does continuous stimulation flatten GH pulses?: Ionescu and Frohman reported pulsatile GH secretion persisting during continuous stimulation, with the pituitary imposing its own rhythm.

Extended research context

The CJC-1295 & Ipamorelin deep dive

Deep dive: why CJC-1295 and Ipamorelin are studied together

CJC-1295 is a modified GHRH (growth-hormone-releasing hormone) analogue; Ipamorelin is a selective growth-hormone secretagogue that binds the ghrelin receptor (GHS-R1a). In pituitary-cell research models the two act on independent pathways whose downstream effect converges on GH release. CJC-1295 amplifies the endogenous GHRH signal while Ipamorelin adds a separate ghrelin-pathway stimulus. That's why supplier catalogues frequently package them together as a research reference blend.

DAC vs no-DAC: which CJC-1295 is which

'CJC-1295 with DAC' contains a Drug Affinity Complex (a Lys-maleimide moiety) that binds serum albumin and extends half-life to several days. 'CJC-1295 no-DAC' (also called Modified GRF 1-29) lacks the linker and clears in minutes. These are pharmacologically different peptides. A CoA must specify which form is in the vial; mass differs (~3,367 Da with DAC vs ~3,367 minus linker for no-DAC).

Ipamorelin's selectivity profile

Unlike earlier GHS-R agonists (e.g. GHRP-6), Ipamorelin was engineered for minimal cross-activity at cortisol- and prolactin-releasing pathways in research models. That receptor selectivity is why it is the reference secretagogue for controlled pituitary-cell studies.

Research applications

▸Pituitary-cell GH-release assays (comparator vs GHRH and hexarelin)
▸Half-life comparison studies: DAC vs no-DAC CJC-1295 forms
▸Ghrelin-receptor binding assays for Ipamorelin analogue development
▸Analytical HPLC method development for lipidated GHRH analogues
▸Stability testing under refrigerated storage

Handling checklist

✓Store lyophilised at −20 °C long-term
✓Reconstitute in bacteriostatic water; both peptides dissolve readily
✓Aliquot immediately, refrigerate at 2–8 °C, use within 28 days
✓Confirm salt form and DAC/no-DAC status on CoA before starting a study
✓Do not use for human administration (research reference only)

Common research-handling mistakes

Learnt from thousands of researcher orders across our UK labs.

✗ Confusing DAC and no-DAC CJC-1295

Fix: Check the CoA. The two have very different pharmacokinetics.

✗ Assuming Ipamorelin acts on GHRH receptors

Fix: It binds the ghrelin receptor (GHS-R1a), a separate pathway from CJC-1295.

✗ Storing reconstituted solution at room temperature

Fix: Refrigerate 2–8 °C after reconstitution.

Continue researching

Peer-reviewed guides, comparators and matched reference materials.

Primary sources & clinical trials

Peer-reviewed research and registered trials from PubMed, ClinicalTrials.gov, PubChem, FDA and NIH. All links open in a new tab and point to the primary source, so every claim can be verified at origin.

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Written and reviewed by

The UK Peptides Editorial Team · Research library, UK Peptides

The editorial team is responsible for supplier selection, batch release decisions and the content published in this research library. Every article here is sourced to primary literature and every product page to a signed third-party certificate. Corrections are made in place and the review date updated.

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How CJC-1295 Works as a GHRH Analogue