Growth hormone secretagogue actions on the pituitary gland: multiple receptors for multiple ligands?
Chen. C C
Key Findings
- GH secretion is regulated by GHRH, somatostatin, and also by synthetic GH‑releasing peptides (GHRPs) via a distinct GHS‑R.
- The GHS‑R is a G‑protein‑coupled receptor cloned from humans, pigs, and rats, suggesting a common but not identical target across species.
- Cell signaling pathways involved include calcium, cAMP, protein kinases A and C, and phospholipase C.
- Species‑specific differences in response to GHRP‑2 indicate the possible existence of more than one GHS‑R subtype.
Practical Outcomes
- For biohackers, this research confirms that GHRP‑2 works through a unique receptor and that its effects can differ between species, which may explain variability in human responses. It suggests caution when extrapolating animal data to dosing protocols and highlights the need for personal experimentation to find the optimal dose.
Summary
The study explains that growth hormone (GH) release is controlled not only by the usual brain hormones but also by synthetic peptides like GHRP‑2, which work through a special receptor (GHS‑R). Different species seem to have slightly different versions of this receptor, meaning the way GHRP‑2 works can vary between animals.
Abstract
1. Growth hormone (GH) secretion is thought to occur under the reciprocal regulation of two hypothalamic hormones, namely GH-releasing hormone (GHRH) and somatostatin (SRIF), through their engagement with specific cell-surface receptors on the anterior pituitary somatotropes. 2. In addition to GHRH and SRIF, synthetic GH-releasing peptides (GHRP) or GH secretagogue(s) (GHS) regulate GH release through the activation of a novel receptor, the GHS receptor (GHS-R). 3. The cloning of the GHS-R from human, swine and rat identifies a novel G-protein-coupled receptor involved in the control of GH secretion and supports the existence of an undiscovered hormone that may activate this receptor. 4. Varieties of intracellular signalling systems are suggested to mediate the action of GHS, which include changes in intracellular free Ca2+ ([Ca2+]i), cAMP, protein kinases A and C, phospholipase C etc. 5. With regard to the use of signalling systems by GHS, especially a new form of GHRP or GHRP-2, a clear species difference has been demonstrated, supporting the possibility of more than one type of GHS-R.
Study Information
pubmed
2000
2000-05-01T00:00:00.000Z
10.1046/j.1440-1681.2000.03258.x
70
66