GHRP-6
Growth Hormone Releasing Peptide-6, Growth hormone-releasing hexapeptide, His-D-Trp-Ala-Trp-D-Phe-Lys-NH2
Postprandial changes in plasma GH and insulin concentrations, and responses to stimulation with GH-releasing hormone (GHRH) and GHRP-6 in calves around weaning.
Katoh. K K; Furukawa. G G; Kitade. K K; Katsumata. N N; Kobayashi. Y Y; Obara. Y Y
Key Findings
- Milk‑based feeding in 3‑week‑old calves sharply increases baseline GH, insulin, and glucose, unlike solid‑food feeding in 12‑week‑old calves.
- Injecting GHRP‑6 (2.5 µg/kg) raises plasma GH in both young and older calves, with a larger overall GH exposure (AUC) in the younger group.
- GHRP‑6 triggers a brief insulin increase only in the older, weaned calves, with a greater insulin AUC compared to younger calves.
Practical Outcomes
- The study shows GHRP‑6 can reliably stimulate growth hormone, but the magnitude may depend on age and nutritional status. For human biohackers, it suggests that younger individuals or those on high‑protein, fast‑digesting diets might experience stronger GH responses, while insulin effects may be more pronounced in older or more metabolically mature users. However, because the data come from calves, direct dosing or protocol recommendations for people remain speculative.
Summary
In young calves that still drink milk, feeding raises their natural growth hormone and insulin levels, while older, weaned calves on solid food don’t see the same boost. Giving the peptide GHRP‑6 makes growth hormone spike in both age groups, but the spike is bigger in the younger calves. Only the older calves show a temporary rise in insulin after GHRP‑6.
Abstract
Changes in plasma concentrations of GH and insulin in response to feeding and stimulation with GH-releasing hormone (GHRH) or GH-releasing peptide (GHRP-6, a ligand for endogenous GH secretagogue receptors) were compared between 3-week-old (milk-fed) and 12-week-old (concentrate and hay-fed) calves. Feeding of a milk-replacer diet in 3-week-old animals significantly increased the basal (prefeeding) concentrations of GH, insulin and glucose in plasma, whereas feeding of concentrate and hay in 12-week-old animals did not cause a significant change in these traits. However, in the animals maintained on a milk-replacer diet until 12 weeks of age, postprandial plasma GH concentrations and AUC (area under the curve) were not different from those in the age-matched weaned group. The venous injection of either GHRH (0.25 microg/kg) or GHRP-6 (2.5 microg/kg) significantly increased plasma GH concentrations in both 3- and 12-week-old animals, but GH AUC was significantly greater in 3-week-old than in 12-week-old animals. Insulin concentration was transiently but significantly increased by the injection of GHRP-6 only in 12-week-old animals, the AUC being greater in 12-week-old than 3-week-old animals. From these results, we conclude that postprandial levels of plasma GH and insulin concentrations are altered after weaning and by aging, and that the quality of diets or development of the neuroendocrine functions in the digestive-pituitary system may be involved in this alteration.
Study Information
pubmed
2004
10.1677/joe.1.05898