GHRP-6
Growth Hormone Releasing Peptide-6, Growth hormone-releasing hexapeptide, His-D-Trp-Ala-Trp-D-Phe-Lys-NH2
Induction of c-fos mRNA in the arcuate nucleus of normal and mutant growth hormone-deficient mice by a synthetic non-peptidyl growth hormone secretagogue.
Sirinathsinghji. D J DJ; Chen. H Y HY; Hopkins. R R; Trumbauer. M M; Heavens. R R; Rigby. M M; Smith. R G RG; van der Ploeg. L H LH
Key Findings
- GHRP‑6 (and another secretagogue) sharply increases c‑fos mRNA—a marker of neuronal activation—in the arcuate‑ventromedial hypothalamus of both wild‑type and growth‑hormone‑deficient mice.
- The response occurs despite the mice lacking functional growth‑hormone or GHRH receptors, indicating a direct central action of the secretagogue.
- Mutant mice (dw/dw and lit/lit) already have a 5‑fold higher baseline GHRH mRNA in the same brain region, yet still show the secretagogue‑induced c‑fos rise.
Practical Outcomes
- For biohackers, the data hint that GHRP‑6 may influence appetite, metabolism, or other hypothalamic functions beyond simply boosting growth‑hormone levels. However, the work is in mice and focuses on gene expression, so it doesn’t provide dosing guidance or proven human benefits. Use this as a mechanistic clue rather than a direct protocol recommendation.
Summary
The study shows that the synthetic peptide GHRP‑6 activates brain cells in the hypothalamus (the ARC‑VMH area) of both normal mice and mice that can’t make growth hormone. This activation happens even when the usual growth‑hormone pathways are broken, meaning GHRP‑6 likely works directly on brain neurons that control growth‑hormone release, not just by raising hormone levels in the blood.
Abstract
We have studied by in situ hybridization histochemistry the mRNA expression of the c-fos immediate early gene in the brains of wild type and dwarf(dw/dw) and little(lit/lit) mutant mice after systemic injections of the synthetic GH secretagogues GHRP-6 and L-163,191. Both GH secretagogues induced a marked c-fos mRNA expression in the arcuate-ventromedial hypothalamus (ARC-VMH) of both control and mutant mice indicating a possible action on growth hormone releasing hormone (GHRH) neurones in the ARC-VMH. Both dw/dw and lit/lit mice showed a 5-fold elevation in GHRH mRNA expression in the ARC-VMH compared with control animals under basal conditions. Since lit/lit mice have a reduced ability to secrete GH and lack a functional GHRH receptor while dw/dw mice lack both GH and presumably GHRH receptors, the GH-secretagogue-induced c-fos mRNA in the brain of these mutants are unlikely to be mediated by an indirect action of GH or a interaction of the synthetic GH-secretagogue with the GHRH receptor.
Study Information
pubmed
1995
1995-10-23T00:00:00.000Z
10.1097/00001756-199510010-00009
18