CJC-1295 and Ipamorelin are two distinct synthetic peptides that act at different receptors of the hypothalamic–pituitary growth hormone (GH) axis. CJC-1295 is an analog of growth hormone-releasing hormone (GHRH) that binds the GHRH receptor, while Ipamorelin is a pentapeptide agonist of the ghrelin receptor (GHS-R1a). Because the two receptors use different intracellular signaling routes, each is used as a tool in research that examines how the GHRH and ghrelin receptor systems interact at pituitary somatotroph cells. Neither is approved by the FDA for human or veterinary use, and neither is sold by Excalibur Peptides; this page is for information only. This overview covers their chemistry, receptor pharmacology, research context, analytical characterization and laboratory handling.
CJC-1295 (with DAC): a synthetic analog of GHRH(1-29) with amino-acid substitutions that increase resistance to enzymatic degradation, and a C-terminal lysine carrying a maleimidopropionic acid linker known as the Drug Affinity Complex (DAC). The maleimide group is designed to form a covalent conjugate with cysteine-34 of serum albumin. Molecular weight (with DAC): ~3,647 Da. CAS (with DAC): 863288-34-0. The form without DAC, often called modified GRF(1-29), lacks the albumin-reactive linker.
Ipamorelin: a synthetic pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2) developed at Novo Nordisk as a selective GHS-R1a agonist. Molecular formula: C38H49N9O5. Molecular weight: 711.9 Da. CAS: 170851-70-4. Its non-proteinogenic residues (α-aminoisobutyric acid and D-2-naphthylalanine) and C-terminal amide increase stability against peptidases.
CJC-1295 binds the GHRH receptor, a class B G protein-coupled receptor on anterior pituitary somatotrophs. Receptor activation couples to Gαs, raising intracellular cAMP and activating protein kinase A, which phosphorylates CREB and promotes GH gene transcription and secretion in cultured pituitary cells.
Ipamorelin binds GHS-R1a, a class A G protein-coupled receptor that couples mainly to Gαq/11. Activation stimulates phospholipase C, generating IP3 and diacylglycerol, which mobilize intracellular calcium and activate protein kinase C. GHS-R1a is also expressed in the hypothalamus, where ghrelin-receptor signaling influences somatostatin and GHRH neurons.
Because the two peptides act through separate receptors and second-messenger cascades, each serves as a receptor-selective tool in research on receptor cross-talk at the somatotroph, a topic examined in pituitary cell cultures and animal models.
Ipamorelin selectivity (Raun et al., Eur J Endocrinol, 1998, PMID 9849822): foundational characterization in animal models reported GHS-R1a-mediated GH release without the ACTH and cortisol elevation observed with earlier secretagogues such as GHRP-6 and GHRP-2, establishing Ipamorelin as a selective GHS-R1a tool compound.
DAC chemistry (Jetté et al., Endocrinology, 2005, PMID 15817669): characterized GRF(1-29) analogs bearing an albumin-reactive linker in rat models and in vitro, including the conjugate later designated CJC-1295, and showed that the albumin conjugates retain GHRH receptor activity.
CJC-1295 and Ipamorelin are studied in: GH-axis receptor pharmacology, GHRH receptor and GHS-R1a cross-talk at pituitary somatotrophs, albumin-conjugation chemistry for peptide half-life extension, structure–activity work on GHRH(1-29) analogs, and receptor selectivity profiling of ghrelin-receptor agonists.
Both peptides are characterized by reverse-phase HPLC for purity and mass spectrometry for identity. For CJC-1295 with DAC, the maleimide linker is reactive toward thiols, so method development confirms that the intact linker is present and has not hydrolyzed or formed adducts. Ipamorelin's small size (~712 Da) allows straightforward identity confirmation by electrospray mass spectrometry.
GHRH receptor activity is typically measured by cAMP accumulation in cells expressing the receptor, and GHS-R1a activity by intracellular calcium flux or IP1 accumulation. Primary rat pituitary cell cultures allow both receptors to be studied in native somatotrophs, while transfected cell lines isolate each receptor for selectivity work.
CJC-1295 with DAC — form: lyophilized powder; storage: −20°C, protected from moisture. Ipamorelin — form: lyophilized powder; storage: −20°C, protected from moisture and light.
For research use only. Not for human consumption. Neither peptide is approved by the FDA for human or veterinary use.
They act at different receptors of the GH axis. CJC-1295 binds the GHRH receptor (Gαs/cAMP signaling) and Ipamorelin binds the ghrelin receptor GHS-R1a (Gαq/calcium signaling), so each is used as a receptor-selective tool when studying how the two receptor systems interact at pituitary somatotroph cells.
The DAC version carries a maleimidopropionic acid linker designed to conjugate covalently to serum albumin, which prolongs its persistence in animal plasma. The version without DAC, often called modified GRF(1-29), lacks this linker and is cleared much faster.
Ipamorelin is the pentapeptide Aib-His-D-2-Nal-D-Phe-Lys-NH2 (C38H49N9O5, 711.9 Da), a selective agonist of the ghrelin receptor GHS-R1a.
No. Neither CJC-1295 nor Ipamorelin is approved by the FDA for human or veterinary use. Material sold as a research chemical is supplied for in-vitro laboratory research only and is not for human consumption.