The hexapeptide KP-102 (D-ala-D-beta-Nal-ala-trp-D-phe-lys-NH(2)) stimulates growth hormone release in a cichlid fish (Ooreochromis mossambicus).
Shepherd. B S BS; Eckert. S M SM; Parhar. I S IS; Vijayan. M M MM; Wakabayashi. I I; Hirano. T T; Grau. E G EG; Chen. T T TT
Key Findings
- KP-102 at a low dose (1 ng/g) significantly increased plasma growth hormone in tilapia at 6 and 12 hours post‑injection.
- The effect was comparable to a standard growth‑hormone‑releasing hormone (GHRH) control, though the timing differed.
- KP-102 did not produce significant changes in prolactin levels, indicating some specificity for GH release.
Practical Outcomes
- For biohackers, this research reinforces that GHRPs can activate GH pathways across species, supporting the biological plausibility of using GHRPs in humans. However, the study provides no human dosing or safety data, so it does not change current human protocols and should be viewed as background science rather than a direct guide for supplementation.
Summary
A study in tilapia fish showed that the synthetic peptide KP-102, which belongs to the growth‑hormone‑releasing peptide (GHRP) family, can boost the fish's growth hormone levels after a single injection, confirming that GHRPs work in lower vertebrates as well as mammals.
Abstract
Abstract Studies in mammals have shown that synthetic Met-enkephalin derivatives, called growth hormone-releasing peptides (GHRPs), stimulate growth hormone (GH) release. The present study was conducted to determine whether the GHRP, KP-102, specifically stimulates GH release in a teleost. Tilapia (Oreochromis mossambicus) were given a single intraperitoneal injection of KP-102 (D-Ala-D-beta;-Nal-Ala-Trp-D-Phe-Lys-NH(2)) or bovine GHRH(1-29)-amide or vehicle and blood was sampled at 1, 6 and 12 h after injection. KP-102 was administered at two doses of 1 ng/g and 10 ng/g body weight, whereas GHRH (positive control) was administered at a single dose of 10 ng/g body weight. Plasma levels of tilapia GH and prolactins (tPRL(177) and tPRL(188)) were determined by radioimmunoassay. As expected, GHRH injection significantly (P<0.001) elevated plasma GH levels (ng/ml) in tilapia at 6 h post-injection. KP-102 also significantly elevated GH levels (at the low dose) at 6 (P<0.05) and 12 (P<0.01) hours post-injection. There were no significant effects on plasma PRL(s) levels, although mean levels of both PRLs were elevated at 6 h post-injection. These results show for the first time that GHRPs stimulate GH release in teleosts and suggest that the GHRP receptor and possibly a "Ghrelin-like" ligand are also present in lower vertebrates.
Study Information
pubmed
2000
10.1677/joe.0.167r007