Effects of GHRP-2 and hexarelin, two synthetic GH-releasing peptides, on GH, prolactin, ACTH and cortisol levels in man. Comparison with the effects of GHRH, TRH and hCRH.
Arvat. E E; di Vito. L L; Maccagno. B B; Broglio. F F; Boghen. M F MF; Deghenghi. R R; Camanni. F F; Ghigo. E E
Key Findings
- GHRP‑2 and hexarelin produce comparable, robust GH spikes that exceed the response to GHRH at the same dose.
- Both peptides also raise prolactin, ACTH, and cortisol modestly, with effects similar to TRH (for prolactin) and hCRH (for ACTH/cortisol).
- The GH‑releasing effect diminishes with age, but the relative potency of GHRP‑2 vs. hexarelin remains unchanged.
Practical Outcomes
- For biohackers, GHRP‑2 can be used as an effective GH secretagogue at low microgram‑per‑kg doses, offering similar results to hexarelin. Expect a modest rise in prolactin, ACTH, and cortisol, so monitor these hormones if you’re sensitive to stress or hormonal balance. Older users may see a weaker GH response, so dosage adjustments or combination strategies might be needed.
Summary
In healthy young adults, the synthetic peptides GHRP‑2 and hexarelin trigger a strong rise in growth hormone—stronger than the classic GHRH stimulus—when given at 1‑2 µg per kilogram intravenously. They also cause modest increases in prolactin, ACTH and cortisol, similar to what other hormones (TRH, hCRH) do. In older adults the GH boost is smaller, but the pattern of hormone release is the same.
Abstract
GHRP-2 (D-Ala-D-beta Nal-Trp-D-Phe-Lys-NH2) and Hexarelin (HEX) (His-D-2-methylTrp-Ala-Trp-DPhe-Lys-NH2) are synthetic, non-natural super-analogs of GHRP-6 endowed with potent stimulatory effect on GH secretion and slight stimulatory effect on PRL, ACTH and cortisol levels. Their GH-releasing activity ahs never been compared each other and their effects on PRL, ACTH and cortisol have never been compared with that of other stimuli. To clarify these points, in 6 normal young adults (22-27 yr) we studied the GH, PRL, ACTH and cortisol responses to 1 and 2 micrograms/kg i.v. GHRP-2 and HEX comparing them with that after 1 micrograms/kg i.v. GHRH and 400 micrograms i.v. TRH + 2 micrograms/kg i.v. hCRH. The Gh responses to 2 micrograms/kg i.v. GHRP-2 or HEX, compared with those to 1 microgram/kg GHRH, were also studied in 6 normal elderly subjects (66-73 yr). In young adults 1 microgram/kg i.v. GHRP-2 and HEX induced a similar, strong GH response, which was higher (p < 0.05) than that to GHRH. The administration of 2.0 micrograms/kg i.v. GHRP-2 and HEX again elicited a similar GH response, which was higher (p < 0.05) than that after the 1.0 microgram/kg dose. In elderly subjects, the GH those in young subjects. In young adults, the PRL responses to all doses of GHRP-2 or HEX were similar and lower (p < 0.01) responses were similar to those to hCRH. In conclusion, our results demonstrate that, in man, GHRP-2 and HEX have similar, 2 and HEX is not fully specific, as they induce similar increases in PRL, ACTH and cortisol levels. The PRL-releasing activity of GHRPs is lower than that of TRH while their ACTH/cortisol-releasing activity is similar to that of hCRH.
Study Information
pubmed
1997
10.1016/s0196-9781(97)00016-8