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🔬 General ResearchPublished: August 19, 2026

CJC-1295 (Mod GRF 1-29): Pulsatile Somatotropic Axis Activation & GH Secretion Kinetics

“CJC-1295 without DAC (Modified GRF 1-29) is a tetrasubstituted 29-amino-acid synthetic secretagogue engineered to activate pituitary GHRH receptors, stimulating physiological, pulsatile growth hormone surges with optimal receptor recovery kinetics.”

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FOR IN-VITRO LABORATORY RESEARCH ONLY: This scientific publication is provided strictly for academic and biochemical reference by certified researchers. Materials and compounds referenced are NOT for human consumption, veterinary use, drug manufacture, or direct clinical administration. Statements have not been evaluated by Health Canada or the FDA.

Scientific Research Overview

Abstract & Executive Summary

Growth Hormone-Releasing Hormone (GHRH) is the hypothalamic master peptide responsible for stimulating the production and pulsatile secretion of growth hormone. The biological activity of native GHRH resides entirely within its first 29 amino acids, GHRH(1-29)NH2 (Sermorelin). However, Sermorelin suffers from an extremely short in-vivo half-life (< 10 minutes) due to rapid DPP-4 enzymatic cleavage at the Ala2 position, deamidation at Asn8, and methionine oxidation at Met27.

Modified GRF 1-29 (commonly referred to in laboratory literature as CJC-1295 without DAC) solves these biochemical vulnerabilities through four strategic substitutions, yielding a stable 29-amino-acid peptide with an extended ~30-minute half-life that matches the natural human somatotropic pulse duration.

+----------------------------------------------------------------------------------------------------+
|                                 CJC-1295 TETRASUBSTITUTED BIOCHEMISTRY                             |
+------------------------------------+----------------------------------+-----------------------------+
| Substitution Position             | Chemical Modification            | Biochemical Consequence     |
+------------------------------------+----------------------------------+-----------------------------+
| Position 2                         | D-Alanine (D-Ala2)               | Completely blocks DPP-4     |
| Position 8                         | Glutamine (Gln8)                 | Prevents Asn deamidation    |
| Position 15                        | D-Alanine (D-Ala15)              | Enhances alpha-helicity     |
| Position 27                        | Leucine (Leu27)                  | Eliminates Met oxidation    |
+------------------------------------+----------------------------------+-----------------------------+

Chemical Structure & Sequence Architecture

  • Primary Sequence: Tyr-D-Ala-Asp-Ala-Ile-Phe-Thr-Gln-Ser-Tyr-Arg-Lys-Val-Leu-Ala-Gln-Leu-Ser-Ala-Arg-Lys-Leu-Leu-Gln-Asp-Ile-Leu-Ser-Arg-NH2
  • Molecular Formula: C152H252N44O42
  • Molecular Weight: 3367.97 g/mol
  • CAS Registry Number: 863288-34-0
  • C-Terminal Modification: Carboxamide (-NH2) terminus conferring protection against carboxypeptidase degradation.

    • Mechanism of Action

    CJC-1295 (Mod GRF 1-29) functions as a potent selective agonist at the anterior pituitary GHRH receptor:

    1. Pituitary GHRH Receptor Engagement

    Mod GRF 1-29 binds with nanomolar affinity to the GHRH-R on pituitary somatotrophs:

  • Stimulates Gs-protein alpha subunit coupling, activating adenylyl cyclase.
  • Drives rapid intracellular conversion of ATP to cAMP, activating Protein Kinase A (PKA).

    • 2. Epac & Calcium-Dependent Granule Exocytosis

    PKA and Epac signaling cascades phosphorylate voltage-gated L-type calcium channels, causing influx of extracellular Ca2+:

  • Elevated cytosolic calcium mobilizes growth hormone secretory vesicles to fuse with the plasma membrane, releasing a clean, physiological pulse of growth hormone.

    • 3. Synergistic Co-Activation with GHRPs (Ghrelin Agonists)

    In multi-secretagogue research models, combining CJC-1295 (targeting GHRH-R) with a Growth Hormone Releasing Peptide (GHRP, such as Ipamorelin, targeting the GHS-R1a receptor) produces an exponential, synergistic GH surge:

  • GHRH pathway drives the amplitude of GH release.
  • GHRP pathway blocks somatostatin (the inhibitor) and triggers phosphoinositol/IP3 intracellular calcium release.
  • The simultaneous stimulation results in a massive, clean GH pulse without elevating prolactin or cortisol.

    • 4. Receptor Cycling & Absence of Tachyphylaxis

    Because Mod GRF 1-29 (w/o DAC) has a finite biological half-life (~30 minutes), somatotroph receptors return to baseline between pulses, avoiding the receptor internalization, desensitization, or down-regulation seen with continuous agonists.

    Key Study Highlights

    ✓

    Tetrasubstituted Stability

    D-Ala2, Gln8, D-Ala15, and Leu27 substitutions block DPP-4 and oxidative breakdown.

    ✓

    Pulsatile Secretion Kinetics

    Generates sharp, physiological growth hormone pulses matching circadian somatotropic rhythms.

    ✓

    GHRP / GHS-R1a Synergy

    Produces exponential, synergistic GH surges when co-incubated with ghrelin mimetics.

    ✓

    Receptor Sensitivity Preservation

    Avoids pituitary receptor tachyphylaxis and preserves negative feedback control.

    Scientific FAQs

    CJC-1295 with DAC includes a Drug Affinity Complex that covalently binds albumin, extending half-life to 6-8 days (causing continuous GH release). CJC-1295 without DAC (Mod GRF 1-29) has a ~30-minute half-life, stimulating natural, healthy pulsatile GH release.
    Molecular Formula: C152H252N44O42, Molecular Weight: 3367.97 g/mol, CAS Number: 863288-34-0.
    Reconstitute with sterile Bacteriostatic Water (0.9% benzyl alcohol). Gently stream diluent down the glass vial wall without shaking. Store reconstituted solution at 2°C to 8°C.

    References

    1. Teichman S.L. et al (2006).
      Prolonged stimulation of GH and IGF-I by CJC-1295
      J Clin Endocrinol Metab, 91(3):799-805
      View Research Paper ↗
    2. Izdebski J. et al (2002).
      Structure-activity relationships of GHRH analogs
      J Pept Sci, 8(6):289-296
      View Research Paper ↗

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