What Is a GHRP? Growth Hormone-Releasing Peptides
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GHRP (growth hormone-releasing peptide)

Also called GHRP, GHRP-6, GHRP-2, growth hormone-releasing peptide · Reviewed

Definition: A GHRP (growth hormone-releasing peptide) is a small synthetic peptide that makes the pituitary release growth hormone. GHRPs act on a different receptor from GHRH: the growth hormone secretagogue receptor, whose natural signal turned out to be ghrelin. GHRP-6, GHRP-2 and ipamorelin belong to this group.

Where GHRPs came from

GHRPs were made in the lab before anyone knew which body signal they copied. A 1984 study compared a six amino acid synthetic GHRP with GRF-44 in rat pituitary cells. Both released GH, but GRF-44 was 60 times more potent and each seemed to work by a slightly different route.

In 1999, Kojima and colleagues found ghrelin, the body's own signal for that receptor. Their paper notes the GH secretagogues act through a receptor separate from the one GHRH uses.

How the common GHRPs differ

Raun 1998 compared them in animals. Ipamorelin, a 5 amino acid peptide, released GH with potency and efficacy similar to GHRP-6. GHRP-6 and GHRP-2 also raised ACTH and cortisol, the stress hormones; ipamorelin did not, even at doses more than 200 times its effective dose. None of them changed FSH, LH, prolactin or TSH.

Counting the chain

  1. The 1984 GHRP is His-DTrp-Ala-Trp-DPhe-Lys-NH2: 6 amino acids.
  2. Ipamorelin is Aib-His-D-2-Nal-D-Phe-Lys-NH2: 5 amino acids.
  3. Ghrelin, the natural signal, is 28. All are well under the 40 amino acid line for a peptide.

These are animal and lab findings. We found no FDA label on DailyMed for GHRP-6, GHRP-2 or ipamorelin.

If you log one of these, note the name exactly as on the vial. GHRP-6 and GHRP-2 are different molecules, and the number is part of the name, not a dose.

Read more on Dose Track: Ipamorelin guide · CJC-1295 and ipamorelin blend

General education drawn from labels and published studies, not personal medical advice. Your prescriber, pharmacist and the label that came with your product are the final word.
Growth hormone secretagogueA growth hormone secretagogue is a compound that makes your pituitary gland release more of its own growth… GhrelinGhrelin is a peptide hormone first purified from the stomach. It raises appetite and triggers growth… GHRH (growth hormone-releasing hormone)GHRH (growth hormone-releasing hormone, also called GRF) is a hormone made in the hypothalamus, part of… PeptideA peptide is a short chain of amino acids, the same building blocks that make up proteins. US rules draw… Research use only (RUO)Research use only (RUO) is a label phrase. In US rules it comes from labeling for in vitro diagnostic…

Frequently asked questions

What is the difference between a GHRP and GHRH?+
Both trigger growth hormone release, but through different receptors. GHRH analogs use the GHRH receptor. GHRPs use the growth hormone secretagogue receptor, the one ghrelin acts on.
Is ipamorelin a GHRP?+
Yes. A 1998 study described ipamorelin as a GHRP-receptor agonist that, in animals, released growth hormone without raising cortisol the way GHRP-6 and GHRP-2 did.

Sources

  1. Badger TM et al. The effects of GH-releasing peptides on GH secretion in perifused pituitary cells of adult male rats. Endocrinology 1984. PMID 6148232
  2. Kojima M et al. Ghrelin is a growth-hormone-releasing acylated peptide from stomach. Nature 1999. PMID 10604470
  3. Raun K et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol 1998. PMID 9849822

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