GHRP-6
Growth Hormone Releasing Peptide-6, Growth hormone-releasing hexapeptide, His-D-Trp-Ala-Trp-D-Phe-Lys-NH2
Temporal patterns of increased growth hormone secretion in mice after oral administration of L-ornithine: possible involvement of ghrelin receptors.
Taniguchi. Emi E; Hattori. Ayumi A; Kurogi. Kaito K; Hishida. Yukihiro Y; Watanabe. Fumiko F; Furuse. Mitsuhiro M; Yasuo. Shinobu S
Key Findings
- Oral l‑ornithine raises plasma GH levels in mice, first detectable ~150 minutes after dosing and sustained for >90 minutes.
- The GH increase is completely blocked by the ghrelin‑receptor antagonist [D‑Lys³]‑GHRP‑6, but not by antagonists of somatostatin or GHRH.
- These results indicate that l‑ornithine stimulates GH release via ghrelin‑receptor‑mediated pathways.
Practical Outcomes
- For biohackers, the study suggests that oral ornithine could be a delayed‑acting way to boost growth hormone through the ghrelin system, and that GHRP‑6 (as an agonist) might achieve a similar effect more directly. Timing of dosing matters, and human data are still needed before applying this protocol.
Summary
In mice, taking the amino acid l-ornithine by mouth makes the body release more growth hormone, but the rise starts about 2½ hours after the dose and lasts for over an hour. This hormone boost disappears when a drug that blocks the ghrelin receptor (a version of the peptide GHRP‑6) is given, showing the effect works through that receptor. Other hormone pathways weren’t involved.
Abstract
l-Ornithine is known to stimulate growth hormone (GH) release in mammals. Here, we demonstrated that increases in plasma GH levels after oral administration of l-ornithine were first observed 150 min after administration, and the elevated levels were sustained for more than 90 min in mice. The increase was significantly delayed compared with the reported timing of plasma and tissue levels of l-ornithine after administration. The l-ornithine-induced increase in GH release was completely blocked by [D-Lys<sup>3</sup>]-GHRP-6, a ghrelin receptor antagonist, but not by cyclosomatostatin or JV-1-38, antagonists of somatostatin and GH-releasing hormone, respectively. These results suggest the involvement of ghrelin receptor-mediated pathways in l-ornithine-induced increases in GH release.
Study Information
pubmed
2022
2022-07-26T00:00:00.000Z
10.1292/jvms.22-0125
1
22