Growth hormone releasing peptides: a comparison of the growth hormone releasing activities of GHRP-2 and GHRP-6 in rat primary pituitary cells.
Cheng. J J; Wu. T J TJ; Butler. B B; Cheng. K K
Key Findings
- GHRP-2 and GHRP-6 both stimulate GH release via the same receptor in rat pituitary cells.
- Both peptides act synergistically with GHRF, enhancing GH secretion.
- Combining GHRP-2 and GHRP-6 at maximal doses offers no additional GH release beyond using either alone.
- Repeated exposure to one GHRP can desensitize cells to the other, but not to GHRF.
Practical Outcomes
- For biohackers, using either GHRP-2 or GHRP-6 alone (not both together) with a GHRF peptide is the most efficient way to boost growth hormone. Stacking the two GHRPs provides no extra benefit and may lead to quicker desensitization, so protocols should avoid simultaneous use.
Summary
The study shows that GHRP-2 triggers growth hormone release in rat pituitary cells just like GHRP-6, works best when paired with growth hormone‑releasing factor (GHRF), and doesn’t give extra benefit when both GHRP‑2 and GHRP‑6 are taken together. The two peptides can make each other less effective over time, but they don’t affect the response to GHRF.
Abstract
In the present study, the effect of GHRP-2 on GH release was evaluated in rat primary pituitary cells, and the results were compared with those elicited by GHRP-6. In the rat system, GHRP-2, like GHRP-6, acts synergistically with GRF to release GH. Co-administration of GHRP-2 and GHRP-6 at maximal concentrations had no further effect on GH release than either one alone. The GHRP's were able to desensitize cells to each other, but not to GRF. The effect of GHRP-2 was inhibited by Peptide Antagonist, but was not affected by a GRF antagonist. In conclusion, GHRP-2 was found to stimulate GH release from rat pituitary cells via the same receptor and mechanism as GHRP-6, despite the structural difference between the peptides.
Study Information
pubmed
1997
10.1016/s0024-3205(96)00655-8