GHRH Analogs ExplainedCJC-1295, Sermorelin, Tesamorelin — Research Guide by QSC Peptides

Endogenous Growth Hormone-Releasing Hormone (GHRH) is a 44-amino-acid peptide released from the hypothalamic arcuate nucleus in pulses. It binds the GHRH receptor (GHRHR) — a Gs-protein-coupled receptor expressed on anterior pituitary somatotroph cells — activating the following cascade:

GHRHR → Gs → adenylyl cyclase → ↑cAMP → PKA activation → CREB phosphorylation → GH gene transcription → GH granule priming + secretion

All QSC Peptides GHRH analogs (Sermorelin, CJC-1295, Tesamorelin) activate this same pathway. Their key differences lie in structural modifications that extend half-life and improve resistance to plasma DPP-IV degradation.

The DPP-IV Problem

Dipeptidylpeptidase IV (DPP-IV) cleaves the Tyr1-Ala2 dipeptide bond of native GHRH, inactivating it within 2–5 minutes in plasma. This rapid degradation is the primary obstacle to exogenous GHRH research — and the key engineering challenge addressed by each QSC Peptides GHRH analog:

• Sermorelin: No DPP-IV protection — closest to native GHRH, shortest t½ (~10–20 min)
• CJC-1295 (No DAC): 4 amino acid substitutions block DPP-IV access → t½ ~30 min
• CJC-1295 (With DAC): + albumin-binding DAC linker → t½ ~6–8 days
• Tesamorelin: Trans-3-hexenoic acid N-terminal cap → t½ ~90 min