GHRP-6
Growth Hormone Releasing Peptide-6, Growth hormone-releasing hexapeptide, His-D-Trp-Ala-Trp-D-Phe-Lys-NH2
Mechanism of action of hexarelin and GHRP-6: analysis of the involvement of GHRH and somatostatin in the rat.
Conley. L K LK; Teik. J A JA; Deghenghi. R R; Imbimbo. B P BP; Giustina. A A; Locatelli. V V; Wehrenberg. W B WB
Key Findings
- Both hexarelin (25 µg/kg) and GHRP‑6 trigger strong GH spikes in awake, non‑stressed rats.
- Blocking GHRH or somatostatin with specific antisera does not stop the GH response, suggesting a direct pituitary effect.
- Hexarelin’s GH response was actually higher when somatostatin was blocked, while GHRP‑6’s response was unchanged.
Practical Outcomes
- For biohackers, the data supports the idea that GHRP‑6 (and hexarelin) can reliably boost GH even if your body’s GHRH or somatostatin balance is off, making them useful for consistent GH elevation. However, the study is in rats, so human dosing and safety still need careful consideration, and the findings don’t change existing dosing protocols dramatically.
Summary
In rats, the GH‑releasing peptides hexarelin and GHRP‑6 still cause a big rise in growth hormone even when the normal regulators (GHRH or somatostatin) are blocked. This means the peptides can act directly on the pituitary, not just by tweaking those other hormones.
Abstract
We have recently reported oral and parenteral bioactivity for a new GH-releasing peptide, hexarelin. In the present study, we have examined the neuroendocrine mechanism by which hexarelin and GHRP-6, two GH-releasing peptides, mediate their actions. Although previous studies have looked at the role of growth hormone-releasing hormone (GHRH) and somatostatin in regulating the action of GHRP-6 in culture and in stressed animals, our study looked at the role of both somatostatin and GHRH in regulating the action of hexarelin as well as GHRP-6 in conscious and freely-moving, nonstressed rats. Adult male rats, prepared with indwelling jugular catheters, were pretreated i.v. with either control antiserum (CTLas), growth hormone-releasing hormone antiserum (GHRHas), somatostatin antiserum (SSas), or both GHRHas and SSas. Animals were then treated i.v. with 25 micrograms/kg of either hexarelin or GHRP-6 4 h after i.v. antisera pretreatment. Blood samples were collected every 20 min for the 3 h prior to peptide treatment and at 5, 10, 15, 20, 40 and 60 min following hexarelin or GHRP-6 injection. The peak plasma GH responses in rats pretreated with CTLas were 552 +/- 125 ng/ml following hexarelin administration and 386 +/- 132 ng/ml following GHRP-6 administration. Rats pretreated with SSas exhibited peak GH responses following hexarelin or GHRP-6 of 702 +/- 115 and 312 +/- 42 ng/ml, respectively. These plasma GH responses were similar to those observed in the CTLas-pretreated animals.(ABSTRACT TRUNCATED AT 250 WORDS)
Study Information
pubmed
1995
10.1159/000126826
59