GHRP-6
Growth Hormone Releasing Peptide-6, Growth hormone-releasing hexapeptide, His-D-Trp-Ala-Trp-D-Phe-Lys-NH2
A non-opioid pattern characterizes inhibition of growth hormone releasing peptide binding by dynorphin-related peptides.
Codd. E E EE; Aloyo. V J VJ; Walker. R F RF
Key Findings
- Dynorphin A strongly inhibits the binding of GHRP-6 to its target.
- The inhibition is non‑opioid, as the truncated peptide des‑Tyr‑dynorphin is equally effective.
- A kappa‑opioid selective ligand (U‑50,488) only weakly blocks GHRP-6 binding, confirming the non‑opioid nature of the interaction.
Practical Outcomes
- For biohackers using GHRP-6, be aware that high levels of dynorphin (or substances that raise dynorphin) could reduce the peptide’s effectiveness. Opioid drugs are unlikely to interfere with GHRP-6’s action, so focus on managing endogenous dynorphin pathways rather than opioid interactions.
Summary
GHRP-6 is a peptide that makes the body release growth hormone. This study shows that another peptide called dynorphin can block GHRP-6 from binding, but it does so through a non‑opioid mechanism. Opioid‑type drugs don’t seem to affect GHRP-6 much, so the interaction is specific to dynorphin‑related pathways.
Abstract
GHRP-6 (His-D-Trp-Ala-Trp-D-Phe-LysNH2; SK&F 110679) is a hexapeptide that specifically releases growth hormone. Although derived from methionine enkephalin, 3H-SK&F 110679 binding profiles suggest that it retains little mu or delta opioid activity. In the present study, dynorphin A was a potent inhibitor of SK&F 110679 binding. However, detailed structure-activity studies using dynorphin-related compounds suggest that the interaction between SK&F 110679 and dynorphin was non-opioid in nature. The non-opioid peptide des-Tyr-dynorphin was virtually as potent an inhibitor of 3H-SK&F 110679 binding as the intact dynorphin peptide. Additionally, the non-peptide, kappa selective ligand U-50,488 was a very weak inhibitor of 3H-SK&F 110679 binding. Since dynorphin but not U-50,488 has been reported to release growth hormone, the present results suggest that a non-opioid dynorphin site participates in SK&F 110679's growth hormone releasing action.
Study Information
pubmed
1990
10.1016/0143-4179(90)90144-n