CJC-1295

Both share the same modified GHRH(1-29) backbone with four protease-resistant substitutions (D-Ala2, Gln8, Ala15, Leu27). The DAC variant adds a C-terminal maleimidopropionyl-lysine linker that covalently anchors the peptide to serum albumin's Cys34, extending plasma half-life to roughly 5.8-8.1 days (Teichman et al. 2006). The no-DAC variant - sometimes called Modified GRF(1-29) or Mod GRF 1-29 - omits that linker, so plasma half-life is roughly 30 minutes and the pharmacological profile approximates a single endogenous GHRH pulse rather than sustained receptor agonism.

A ~30-minute plasma half-life produces a sharp, pulsatile rise and fall in GH that resolves over hours, rather than the multi-day plateau seen with CJC-1295 DAC. For researchers this matters because endogenous GHRH is itself pulsatile, and somatotroph responsiveness, receptor desensitization, and IGF-1 feedback all depend on pulse architecture. The no-DAC variant lets investigators model discrete GHRH events while keeping the four protease-resistant substitutions that make in vitro and preclinical work practical.

CJC-1295 binds the GHRH receptor on anterior pituitary somatotrophs - a class B (secretin-family) G-protein-coupled receptor. Activation signals through Gαs, adenylyl cyclase, and the cAMP/PKA cascade that drives GH gene transcription and pulsatile GH secretion. The four amino acid substitutions (D-Ala2, Gln8, Ala15, Leu27) protect the peptide from DPP-IV and trypsin-like proteolysis, but without the DAC linker there is no covalent serum-albumin anchor, so circulation time and biological effect remain short.

Somatotrophs are activated by two converging pathways: GHRH-receptor agonism (which CJC-1295 provides) and growth hormone secretagogue receptor (GHS-R / ghrelin receptor) agonism (which ipamorelin, GHRP-2, and GHRP-6 provide). When both receptors are activated simultaneously the GH response is markedly larger than either ligand alone. Pairing a short-acting GHRH analog like CJC-1295 (no DAC) with a selective GHS-R agonist like ipamorelin is a common in vitro and preclinical design for studying this cooperative pulse-amplitude effect without the confound of sustained albumin-bound peptide exposure.

It functions as a protease-stable, short-duration GHRH-R agonist - a useful tool for separating acute GHRH pharmacology from the chronic receptor occupancy that defines CJC-1295 DAC. Common use cases include studying pulsatile GH secretion, GHRH-R / GHS-R synergy with co-administered secretagogues, comparative pharmacokinetics versus the DAC variant, and receptor desensitization kinetics in preclinical endocrinology models. Sold for in vitro and preclinical research use only.

Store lyophilized powder at -20°C protected from light for long-term stability. Reconstitute with bacteriostatic water by injecting solvent down the vial wall and gently swirling - avoid vigorous shaking, which can foam and shear the peptide. Store reconstituted solution at 2-8°C and use within 14 days; avoid repeated freeze-thaw cycles. Without the maleimide moiety of the DAC variant, the no-DAC peptide is somewhat more tolerant of handling, but gentle technique is still standard practice.