GHRP-6
Growth Hormone Releasing Peptide-6, Growth hormone-releasing hexapeptide, His-D-Trp-Ala-Trp-D-Phe-Lys-NH2
Effect of GHRP-6 and GHRH on GH secretion in rats following chronic glucocorticoid treatment.
Voltz. D M DM; Piering. A W AW; Magestro. M M; Giustina. A A; Wehrenberg. W B WB
Key Findings
- GHRP‑6 increases plasma GH in rats in a dose‑dependent manner (1, 4, 25 µg/kg).
- Chronic glucocorticoid (dexamethasone) treatment blunts the GH response to both GHRP‑6 and GHRH.
- Combining GHRP‑6 with GHRH does not produce a synergistic increase in GH beyond what each peptide does alone.
Practical Outcomes
- For biohackers, GHRP‑6 can still stimulate GH even if you’re taking glucocorticoids or under high stress, but expect a weaker effect. Adding GHRH to a GHRP‑6 regimen is unlikely to boost GH further. When planning GH‑boosting protocols, consider the impact of steroids or chronic stress on the overall response.
Summary
In rats, the peptide GHRP‑6 raises growth hormone (GH) levels in a dose‑dependent way, even when the animals are on a steroid (dexamethasone) that normally suppresses GH. However, the steroid still cuts the GH boost in half, and giving GHRP‑6 together with the natural GH‑releasing hormone (GHRH) doesn’t give any extra benefit.
Abstract
The aim of our study was to investigate the effects of His-DTrp-Ala-Trp-Phe-Lys-NH2 (GHRP-6) on baseline and growth hormone-releasing hormone (GHRH) stimulated growth hormone (GH) release in conscious, freely-moving rats receiving chronic glucocorticoid treatment. Animals were treated daily for seven days with either vehicle or dexamethasone (dex, 40 micrograms/day). On the day of experimentation, rats received an i.v. injection of saline or GHRP-6 followed 15 min later by an i.v. injection of saline or rat GHRH. Three doses of GHRP-6 were evaluated, 1 microgram, 4 micrograms and 25 micrograms/kg; one dose of GHRH was evaluated, 500 ng/kg. GHRP-6 increased plasma GH levels over baseline concentrations in a dose-dependent fashion both in vehicle- and dex-treated rats. The GH response to GHRP-6 and GHRH was significantly less in dex-treated rats as compared to vehicle-treated rats. The combined administration of GHRP-6 and GHRH did not result in any change in plasma GH levels which could not be predicted from the administration of either peptide alone. Our results show that GHRP-6 is able to stimulate GH secretion in glucocorticoid-treated rats but it is unable to counteract the glucocorticoid-induced inhibition of GH secretion.
Study Information
pubmed
1995
10.1016/0024-3205(94)00478-b