CJC-1295 is a tetrasubstituted 29-amino acid peptide analogue of human growth hormone-releasing hormone (GHRH) studied extensively within neuroendocrine and physiological research models. Designed to overcome the short biological half-life of native GHRH(1-29), the compound exists in two primary formulations: Modified GRF(1-29) without Drug Affinity Complex (DAC) and CJC-1295 with DAC. In laboratory environments, researchers evaluate CJC 1295 dosage protocols to analyze somatotroph recruitment, growth hormone (GH) secretion dynamics, insulin-like growth factor-1 (IGF-1) transcription, and metabolic substrate oxidation in animal tissue and cell culture models.
What is CJC 1295 Dosage?
CJC-1295 is classified structural-biochemically as a synthetic secretagogue analogue of endogenous growth hormone-releasing hormone. Its design builds upon the truncated active fragment of natural hypothalamic GHRH, known as Sermorelin or GHRH(1-29). The primary sequence of modified GRF(1-29) contains 29 amino acids, featuring four specific amino acid substitutions at positions 2, 8, 15, and 27: 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.
These targeted substitutions alter the biochemical resistance of the molecule. Substituting D-alanine at position 2 protects the N-terminal peptide bond from rapid cleavage by dipeptidyl peptidase-IV (DPP-IV), which otherwise inactivates native GHRH within minutes. Additional substitutions of glutamine at position 8, alanine at position 15, and leucine at position 27 enhance α-helical secondary structure stability and prevent oxidative degradation.
Without further modification, this tetrasubstituted peptide—frequently designated as CJC-1295 without DAC or Modified GRF(1-29)—possesses a molecular formula of C152H252N44O42 and a molecular weight of approximately 3367.9 g/mol. The extended variant, CJC-1295 with DAC, incorporates a maleimido-propionic acid linker bound to the C-terminal lysine residue. This functional group covalently binds to circulating albumin in-vivo via cysteine-34 thiol reactivity, raising the molecular weight and extending the clearance half-life from roughly 30 minutes to 6–8 days in laboratory models. Discovery of the peptide arose from efforts by ConjuChem Inc. during the late 1990s and early 2000s to create bioconjugate drug technologies capable of prolonging peptide hormone activity.
Mechanism of Action
CJC-1295 functions as a selective agonist at the growth hormone-releasing hormone receptor (GHRHR), a class B G-protein coupled receptor expressed primarily on the cell membranes of anterior pituitary somatotrophs. Receptor engagement initiates a classic intracellular signaling cascade mediated via the stimulatory G-protein subunit (Gs).
Upon ligand binding, the activated Gs subunit stimulates membrane-bound adenylyl cyclase, converting adenosine triphosphate (ATP) into cyclic adenosine monophosphate (cAMP). Elevated cytosolic cAMP levels activate protein kinase A (PKA), which subsequently phosphorylates downstream target proteins and transcription factors, including the cAMP response element-binding protein (CREB).
This phosphorylation cascade triggers two distinct biological events within the somatotroph:
PKA-mediated activation opens voltage-gated L-type calcium channels, inducing an influx of extracellular calcium ions (Ca2+) that promotes immediate exocytosis of pre-stored growth hormone secretory granules into the intercellular space.
Nuclear CREB phosphorylation enhances the transcription of the growth hormone gene, increasing structural synthesis of new hormone stores over extended experimental intervals.
Because CJC-1295 acts as an upstream GHRHR agonist rather than a direct growth hormone substitute, it relies on intact pituitary cellular machinery. Endogenous feedback loops remain operational in preclinical models: circulating GH and downstream liver-derived IGF-1 stimulate hypothalamic somatostatin release, which acts via inhibitory G-protein channels (Gi) to counterbalance adenylyl cyclase activation. When evaluating a CJC 1295 dosage design, researchers observe that the absence or presence of the DAC moiety influences whether GH release manifests as discrete pulsatile bursts or as a sustained baseline elevation.
What the Research Shows
Preclinical and clinical investigation into CJC-1295 has focused on defining pharmacokinetic parameters, somatotroph sensitivity, longitudinal endocrine responses, and tissue growth in genetic knockout models.
1. In-Vivo Bioconjugation and Pharmacokinetic Profile
In foundational rodent and non-human primate studies published in PubMed, researchers evaluated the covalent albumin-binding capabilities of the DAC-modified hGRF(1-29) analogue. The study tested subcutaneous administration across varying concentration ranges in rat models to measure plasma stability and GHRH receptor stimulation.
The investigators observed that CJC-1295 containing the maleimido functional group rapidly bound endogenous serum albumin following injection. This bioconjugation protected the peptide backbone from renal clearance and enzymatic degradation by DPP-IV. A single subcutaneous dose in murine models sustained elevated plasma GH levels for over 24 hours, whereas native GHRH(1-29) demonstrated a clearance half-life under 10 minutes.
2. Normalization of Phenotype in Knockout Models
In a knockout model study indexed on PubMed Central, researchers tested CJC-1295 in GHRH-deficient knockout mice to observe whether long-acting GHRH receptor stimulation could restore normal physiological growth metrics.
The experimental protocol administered once-daily subcutaneous doses of CJC-1295 or vehicle control over a 5-week treatment period. The study reported that daily CJC 1295 dosage administration normalized total body weight, linear bone growth, and lean tissue mass in GHRH knockout mice compared to wild-type controls. Northern blot analysis confirmed increased pituitary growth hormone RNA expression and total pituitary GH content, demonstrating that sustained GHRHR receptor occupation can preserve somatotroph function in absolute endogenous deficiency states.
3. Human Clinical Pharmacokinetics and Pulsatility Analysis
A landmark clinical trial published in PubMed investigated the endocrine effects of CJC-1295 in healthy adult human subjects. The protocol examined single doses ranging from 30 to 90 mcg/kg alongside multiple-dose regimens over several weeks.
Deconvolution analysis of 24-hour GH release profiles revealed that a single CJC 1295 dosage elevated baseline GH concentrations 2- to 10-fold and increased total circulating IGF-1 levels 1.5- to 3-fold for up to 14 days. Crucially, the researchers documented that despite continuous, sustained GHRH receptor stimulation provided by the albumin-bound peptide, physiological pulsatile GH release was preserved. The underlying nocturnal secretory pulses continued, superimposed upon an elevated baseline trough concentration, illustrating that hypothalamic somatostatin feedback retains its counter-regulatory control.
Research Applications
Laboratory research surrounding CJC-1295 encompasses several key biochemical and physiological domains:
Pituitary GHRH Receptor Kinetics: Evaluating receptor activation, ligand-receptor binding affinity, GPCR desensitization pathways, and somatotroph intracellular signaling cascades.
Somatotroph Secretory Pulsatility: Analyzing differences in total endocrine output when comparing short-acting pulsatile agonists (Modified GRF 1-29) against continuous GHRHR activation models (CJC-1295 with DAC).
IGF-1 Axis Gene Expression: Measuring downstream transcription of hepatic IGF-1, skeletal tissue IGFBP-3, and local tissue growth factor expression in response to sustained hormone exposure.
Combination Secretagogue Models: Studying the synergistic interactions between GHRH receptor agonists (such as CJC-1295) and ghrelin receptor agonists (such as Ipamorelin or GHRP-6) on intracellular calcium flux.
Bioconjugate Chemistry: Using the maleimido-propionic acid linker technology as a experimental template for extending the circulating half-life of small structural peptides in preclinical drug design.
Purity, Storage and Handling
Maintaining rigorous analytical standards is essential when handling CJC-1295 for laboratory assays. Because degradation accelerates once reconstituted, batch-level HPLC verification matters more here than with more stable peptides. UK laboratories sourcing CJC 1295 dosage references or evaluating research materials from suppliers like Peptides Lab UK should expect a batch-specific certificate of analysis and lyophilised storage at -20C. Facilities evaluating Where to buy peptides in UK must review high-performance liquid chromatography (HPLC) and mass spectrometry (MS) documentation to confirm a minimum purity threshold of 98%.
HPLC analysis verifies chemical purity by measuring peak area percentage, ensuring the absence of deletion sequences or truncated fragments resulting from incomplete solid-phase peptide synthesis (SPPS). Mass spectrometry confirms exact molecular weight (3367.9 g/mol for non-DAC; ~3648 g/mol for DAC-modified variants). High purity prevents non-specific receptor binding or unexpected cellular toxicity during sensitive cell culture trials.
Storage Specifications
Lyophilized CJC-1295 powder should be stored under the following conditions:
Temperature: Store at -20°C for routine research use, or at -80°C for long-term storage spanning beyond 12 months.
Desiccation: Keep vials in sealed containers with active desiccants to prevent hydrolytic degradation caused by atmospheric moisture exposure.
Light Sensitivity: Protect vials from direct ultraviolet and ambient room light, as specific amino acid residues (such as tyrosine and tryptophan) are subject to photo-oxidation.
Reconstitution Protocols
When reconstituting lyophilized CJC-1295 for experimental use, protocols require strict adherence to standard aseptic laboratory methods:
Allow cold vials to reach room temperature before adding solvents to prevent condensation on the interior vial walls.
Reconstitute using sterile laboratory-grade solvents, such as 0.9% bacteriostatic sodium chloride or sterile water for injection, depending on the requirements of the biological assay.
Direct the solvent down the glass container wall rather than spraying directly onto the peptide cake, gently swirling the vial to dissolve the powder. Avoid mechanical shaking or vortexing, which causes structural shearing and protein aggregation.
Once reconstituted, store liquid aliquots at 2°C to 8°C for short-term use, or freeze single-use micro-aliquots at -80°C to avoid damaging repeat freeze-thaw cycles.
Frequently Asked QuestionsWhat is the primary functional difference between CJC-1295 with DAC and without DAC?
CJC-1295 with DAC contains a maleimido linker that binds albumin, extending its clearance half-life to several days. The non-DAC version (Modified GRF 1-29) lacks this linker, resulting in a short half-life of roughly 30 minutes.
How does CJC-1295 interact with the pituitary gland?
CJC-1295 acts as an agonist at the growth hormone-releasing hormone receptor on pituitary somatotrophs. It stimulates adenylyl cyclase and elevates cytosolic cAMP and calcium, driving growth hormone transcription and secretion.
What analytical methods verify the purity of CJC-1295 batches?
High-performance liquid chromatography (HPLC) evaluates purity by confirming peak area ratios above 98%, while mass spectrometry (MS) verifies exact molecular mass and amino acid identity.
What solvent is typically used to reconstitute CJC-1295 for laboratory research?
Reconstitution is generally performed using sterile laboratory-grade solvents, such as 0.9% bacteriostatic sodium chloride or sterile water for injection, under sterile conditions.
This compound is supplied strictly as a lyophilised chemical for in-vitro laboratory research and analytical experimentation only. It is not a pharmaceutical product, medication, or food additive, and is strictly not for human or veterinary use.