CJC-1295 (without DAC) vs Sermorelin

CJC-1295 (without DAC)

CJC-1295 without DAC, also called modified GRF (1-29), is a 29-residue synthetic analogue of growth hormone-releasing hormone (GHRH). Native GHRH has 44 residues, but its first 29 carry the receptor-binding activity, and this peptide is built on that shortened sequence with four amino-acid substitutions intended to slow breakdown. The name causes confusion: CJC-1295 originally referred to a version carrying a drug affinity complex (DAC), a reactive linker that binds albumin and greatly prolongs circulation. The form described here lacks that linker. Human studies of the DAC version exist but are few; published work on the form without DAC is thinner still, and much of what is said about it is inferred from the parent hormone.

Sermorelin

Sermorelin is a synthetic 29-residue peptide reproducing the N-terminal segment of human growth hormone-releasing hormone (GHRH). Native GHRH has 44 residues, and the 1–29 segment, amidated at its C-terminus as here, is reported to retain the receptor activity of the full hormone. Like native GHRH, it is cut quickly by plasma enzymes including dipeptidyl peptidase-4, a property that later analogues such as tesamorelin were modified to avoid. Research on it has centred on growth hormone release from the anterior pituitary, including human physiology studies, many of them decades old, alongside animal and cell work. Recent literature on sermorelin itself is sparse beside that on newer GHRH analogues.

How CJC-1295 (without DAC) acts

Like native GHRH, the peptide has been reported to bind the GHRH receptor, a class B G protein-coupled receptor on somatotroph cells of the anterior pituitary. Receptor activation couples to Gs, raising intracellular cAMP and releasing stored growth hormone; circulating growth hormone in turn drives IGF-1 production, mainly in the liver. The substitutions, D-alanine at position 2, glutamine at 8, alanine at 15 and leucine at 27, were chosen to resist cleavage by dipeptidyl peptidase-4 and to reduce deamidation and oxidation at vulnerable residues. Without the albumin-binding linker its half-life is short, and pharmacokinetic data specific to this form are sparse.

How Sermorelin acts

Sermorelin binds the GHRH receptor, a class B G-protein-coupled receptor on somatotroph cells of the anterior pituitary. Receptor activation has been reported to raise cyclic AMP and activate protein kinase A and the transcription factor CREB, which is linked to transcription of the growth hormone gene as well as to release of stored hormone. Because it acts upstream of the pituitary, the growth hormone released stays subject to inhibition by somatostatin and to negative feedback from IGF-1. This is the main pharmacological difference between GHRH analogues and growth hormone itself.

The records side by side

• Type: CJC-1295 (without DAC), GHRH analog (Modified GRF 1-29); Sermorelin, GHRH analog (growth hormone secretagogue)
• Length: CJC-1295 (without DAC), not recorded; Sermorelin, 29 amino acids
• Molecular weight: CJC-1295 (without DAC), 3647.2 g/mol; Sermorelin, 3357.9 g/mol
• Molecular formula: CJC-1295 (without DAC), C165H269N47O46; Sermorelin, C149H246N44O42S

Reading a comparison

A comparison places two records side by side; it does not merge them. Each description above is drawn from that compound's own record, and the two were not necessarily characterised by the same methods, at the same time, or to the same level of detail. Before comparing any attribute, it is worth establishing that both records describe the substance you think they describe — names are not identifiers, and two entries sharing a name can differ in salt form, stereochemistry or the convention used to state a mass. Where a figure carries no method beside it, the comparison is between two reported numbers rather than between two measurements.