GHRP-6: The First Selective GH Secretagogue Hexapeptide

GHRP-6 sits at the start of a lineage: it was the first of the synthetic growth-hormone-releasing peptides, and it is the compound against which later secretagogues are often compared.

The molecule

GHRP-6 is the hexapeptide His-D-Trp-Ala-Trp-D-Phe-Lys-NH₂ (C₄₆H₅₆N₁₂O₆, ≈ 873 g/mol), first characterized by Bowers and colleagues (Endocrinology, 1984). Its D-amino acid content is what protects it from enzymatic breakdown — an early example of that design trick in peptide drug development.

How it works

GHRP-6 is studied as a GHS-R1a (ghrelin receptor) agonist. The ghrelin pathway is distinct from the GHRH pathway: where GHRH directly drives somatotroph activity, the ghrelin/secretagogue pathway modulates GH release through a separate receptor system. This is why research frequently looks at the two in combination — each pathway contributing a different component of the GH pulse.

Research applications

• Growth-hormone release research — the original and dominant thread
• Ghrelin-receptor pharmacology — binding and selectivity studies against later secretagogues
• Appetite and food-intake pathway studies — ghrelin is an appetite signal, so receptor agonism research spans feeding behavior
• Pulsatility studies — how secretagogue signaling shapes the amplitude and timing of GH pulses

Handling notes

Lyophilized, reconstitute with bacteriostatic water; the reconstitution calculator handles the math. Store at −20°C lyophilized.

See GHRP-6 for CAS, purity and full specifications.

For laboratory research use only. Not medical advice.