Molecular class and origin
CJC-1295 is a peptide analog derived from the biologically active 1-29 fragment of human GHRH (sermorelin, GRF 1-29). Native GHRH is a 44-amino-acid hypothalamic hormone, but the first 29 residues retain full receptor-activating capacity, which is why the 1-29 scaffold is the basis for this analog class.
The molecule incorporates four amino-acid substitutions relative to the native 1-29 sequence — D-Ala at position 2, Gln at position 8, Ala at position 15, and Leu at position 27. These substitutions are engineered to resist enzymatic degradation (notably dipeptidyl peptidase-4 cleavage at the N-terminus) and to reduce oxidation and deamidation, increasing the analog's stability in solution relative to unmodified GRF 1-29.
Receptor target and signaling
CJC-1295 acts as an agonist at the growth-hormone-releasing hormone receptor (GHRHR), a class B G-protein-coupled receptor expressed on somatotroph cells of the anterior pituitary. Agonist binding couples to Gs, activating adenylate cyclase, elevating intracellular cAMP, and engaging protein kinase A signaling.
In the research literature this pathway is characterized as increasing the synthesis and pulsatile release of growth hormone from somatotrophs. Because the mechanism works upstream through the pituitary's own regulatory machinery, the literature frequently frames GHRH analogs as preserving the pulsatile, feedback-regulated character of endogenous secretion rather than overriding it.
The DAC vs no-DAC distinction
The single most important structural variable in CJC-1295 research is the presence or absence of the Drug Affinity Complex (DAC). DAC is a maleimidopropionic-acid (lysine-linked) moiety appended to the peptide that reacts with a free cysteine thiol on circulating serum albumin, forming a reversible covalent conjugate.
CJC-1295 with DAC is albumin-bound in circulation, which shields it from renal clearance and proteolysis and extends its plasma half-life to the order of days in reported models. The no-DAC form — often referred to in the literature as modified GRF(1-29) or 'mod-GRF 1-29' — lacks the albumin-binding element and behaves as a short-acting analog with a half-life on the order of minutes.
This difference matters mechanistically: the long-acting DAC form is studied for its capacity to raise a sustained tonic GHRH tone, whereas the short-acting no-DAC form is studied for producing a discrete, pulse-like stimulus that more closely mimics endogenous GHRH kinetics. Researchers select between them based on the temporal profile a given experiment requires.
- With DAC: albumin-conjugating, long circulating half-life (days), sustained receptor tone.
- No-DAC (mod-GRF 1-29): no albumin binder, short half-life (minutes), pulse-like stimulus.
- Both share the same four-substitution GHRHR-agonist core sequence.
Why it is co-studied with ghrelin-receptor agonists
GHRH-receptor signaling and ghrelin-receptor (GHSR) signaling represent two distinct, complementary axes of somatotroph regulation. Much of the literature pairs a GHRH analog such as CJC-1295 with a selective GHSR agonist such as ipamorelin to examine the interaction of the two pathways in vitro and in animal models. The mechanistic rationale for this pairing is covered in the dedicated comparison reference.
Laboratory handling and verification
As a lyophilized peptide, CJC-1295 is handled under standard cold-chain research practice: reconstitution with an appropriate sterile diluent, aliquoting to minimize freeze-thaw cycles, and storage per the compound's stability profile. The DAC and no-DAC forms have differing stability characteristics that inform handling decisions.
Every Kairo Labs lot is verified to the lot with a Certificate of Analysis documenting identity and purity by mass spectrometry and HPLC, so researchers can confirm which analog form and what purity they are working with before experimental use.