Short answer
What is CJC-1295? CJC-1295 is a synthetic analog of growth hormone-releasing hormone (GHRH) built on a modified GRF(1-29) backbone with four amino-acid substitutions. It is studied in growth hormone research as a long-acting GHRH receptor agonist. It is sold as a lyophilized research powder and is not for human use.
What is CJC-1295?
CJC-1295 is a 30-residue analog of growth hormone-releasing hormone. It is a member of the GRF (growth hormone-releasing factor) family and is sometimes described as a modified GRF(1-29), because its core corresponds to the first 29 amino acids of GHRH with four substitutions at positions 2, 8, 15, and 27. The peptide was originally developed and characterized in the early 2000s as a candidate for extending the short half-life of native GHRH, which is only a few minutes in circulation [1].
Because native GHRH is rapidly broken down, researchers interested in sustained growth hormone pathway stimulation have studied analogs with structural changes that slow enzymatic degradation. CJC-1295 is one such analog, and its distinguishing feature is the presence or absence of a Drug Affinity Complex (DAC).
CJC-1295 with DAC vs CJC-1295 without DAC
A recurring question in growth hormone research is the difference between the two forms of CJC-1295 sold as research chemicals.
CJC-1295 with DAC. This form carries a maleimidopropionyl linker that covalently attaches to cysteine residues on serum albumin. Binding to albumin shields the peptide from proteases and dramatically extends its time in circulation. In clinical research, a single administration of the DAC form was associated with dose-dependent elevations of growth hormone and insulin-like growth factor-I (IGF-I) lasting up to 11 days, with a reported plasma half-life of 5.8 to 8.1 days [2].
CJC-1295 without DAC (Mod GRF 1-29). This form retains the same four-substitution GRF(1-29) backbone and its resistance to dipeptidyl peptidase-IV (DPP-IV), but lacks the albumin-binding complex. As a result its duration of action is much shorter. Researchers often choose the no-DAC form when they want a more episodic growth hormone stimulation profile rather than a sustained one.
The distinction matters for experimental design: a study that requires sustained receptor occupancy may favor the DAC form, while one that models pulsatile endocrine signaling may favor the no-DAC form.
Mechanism of action
CJC-1295 acts at the growth hormone-releasing hormone receptor (GHRHR) on pituitary somatotroph cells. Binding of the peptide to this G-protein-coupled receptor activates the classic G alpha-s/adenylyl cyclase/cAMP/protein kinase A pathway, which drives the synthesis and release of growth hormone from the anterior pituitary [1][2].
Several features make the analog useful in research:
Because growth hormone secretion is normally regulated by the interplay of GHRH, somatostatin, and ghrelin signaling, compounds that stimulate the GHRH receptor are commonly studied as tools for probing the growth hormone axis in laboratory models.
Research history
CJC-1295 entered the published literature through a 2005 study that identified it as a lead bioconjugate. In that work, three maleimido derivatives of hGRF(1-29) were conjugated to human serum albumin, and CJC-1295 was selected for its activity at the GRF receptor on the anterior pituitary in rats. The compound produced a roughly fourfold increase in growth hormone area under the curve over two hours compared with hGRF(1-29), and remained detectable in plasma beyond 72 hours [1].
A 2006 clinical research study extended these observations to healthy adults. Two randomized, placebo-controlled, ascending-dose trials reported that single administrations produced dose-dependent increases in growth hormone of 2- to 10-fold and 1.5- to 3-fold increases in IGF-I, with IGF-I remaining elevated for up to 11 days [2].
A third line of evidence came from genetic models. A study using the GHRH knockout mouse, which lacks endogenous GHRH signaling, showed that once-daily administration of the long-acting analog normalized growth in these animals [3]. Because the knockout mouse is a well-defined model of disrupted growth hormone axis function, this finding supports the idea that the analog is able to substitute for endogenous GHRH in driving somatic growth in a research setting.
The somatotropic axis in laboratory research
To understand why a GHRH analog like CJC-1295 is studied, it helps to place it within the somatotropic axis, the endocrine circuit that controls growth hormone production. In a normal research setting, growth hormone output from the anterior pituitary is governed by three converging signals: GHRH stimulates it, somatostatin inhibits it, and ghrelin-receptor signaling modulates it. Growth hormone itself then stimulates the liver and peripheral tissues to produce IGF-I, which feeds back to dampen further release.
This circuit is studied across endocrinology, metabolic physiology, and aging research, because the growth hormone axis influences body composition, nutrient partitioning, and tissue maintenance in animal models. Compounds that act on the GHRH receptor, such as CJC-1295, give researchers a way to stimulate the pathway at its first step, upstream of growth hormone and IGF-I. That is a fundamentally different experimental intervention than administering growth hormone directly, which bypasses the pituitary and provides a fixed hormone level rather than engaging the native feedback loop.
In practice, this means CJC-1295 is most often used as a research tool to probe how the hypothalamus-pituitary axis responds to sustained GHRH-receptor stimulation, and to study downstream changes in IGF-I and target tissues. It is not studied as a replacement for growth hormone in any clinical sense; rather, it is a reagent for investigating the physiology of the axis itself.
What research shows about the growth hormone axis
The published work on CJC-1295 is most usefully read as evidence about the growth hormone axis rather than about any single application. Three findings recur across the studies:
Researchers in endocrinology and metabolic physiology use compounds of this class as research tools to study the somatotropic axis, IGF-I signaling, and related feedback circuits.
CJC-1295 compared with related research peptides
CJC-1295 belongs to a family of growth hormone pathway research peptides. Understanding the differences helps researchers select the right tool:
Because GHRH receptor agonists and ghrelin receptor agonists act through complementary pathways, some research protocols combine them. A pre-mixed CJC-1295 + Ipamorelin Blend is available for studies that call for both mechanisms in a single lyophilized product.
How to evaluate research-grade CJC-1295
When sourcing CJC-1295 for laboratory work, the quality markers to verify are the same as for any research peptide:
The 30-residue sequence and the presence or absence of the DAC linker are both details worth confirming with the supplier, since the two forms are used for different experimental purposes.
Storage and handling
Lyophilized CJC-1295 is stable when stored correctly. General laboratory handling guidance applies:
For a detailed step-by-step protocol, see our peptide reconstitution and laboratory handling guide.
Summary
CJC-1295 is a well-characterized long-acting GHRH analog built on a modified GRF(1-29) backbone. Its two commercial research forms differ in whether they carry an albumin-binding DAC, which controls the duration of growth hormone stimulation. Published research documents its receptor pharmacology, its sustained hormone output in clinical studies, and its ability to normalize growth in GHRH knockout mice. As with all research peptides, laboratory-grade CJC-1295 should be verified for HPLC purity, mass-spectrometry identity, and batch-specific COA, and handled according to standard lyophilized-peptide protocols.
FAQ
What is CJC-1295?
CJC-1295 is a synthetic GHRH analog based on a modified GRF(1-29) backbone with four amino-acid substitutions, studied in growth hormone research.
What is the difference between CJC-1295 with DAC and without DAC?
The DAC form carries an albumin-binding complex that prolongs plasma half-life; the no-DAC form (Mod GRF 1-29) has the same backbone but a shorter duration of action.
How does CJC-1295 work?
It activates the GHRH receptor on pituitary somatotrophs to stimulate growth hormone synthesis and secretion, and is resistant to DPP-IV degradation.
What purity should research-grade CJC-1295 have?
At least 98% by HPLC, with identity confirmed by mass spectrometry and a batch-specific COA.