Growth Hormone (GH)
Definition
Growth Hormone (GH), also called somatotropin, is a 191-amino-acid polypeptide hormone synthesised and secreted by somatotroph cells in the anterior pituitary gland. It is the primary hormonal regulator of somatic growth and plays fundamental roles in metabolism, body composition, and tissue repair.
Secretion and Regulation
GH secretion follows a pulsatile pattern, with the largest pulses occurring during deep sleep. Two hypothalamic hormones regulate GH release:
- GHRH (Growth Hormone-Releasing Hormone) — Stimulates GH release by binding GHRH receptors on somatotrophs
- Somatostatin (SST) — Inhibits GH release, creating the pulsatile rhythm
Additionally, ghrelin (acting through GHSR) provides a third regulatory input, amplifying GH pulses. IGF-1 provides negative feedback at both the hypothalamic and pituitary level.
Physiological Effects
GH acts both directly and indirectly (via IGF-1) to influence protein synthesis, lipolysis, glucose metabolism, bone mineralisation, and immune function. GH secretion declines with age — a process termed somatopause — which has motivated research into GH-axis peptides.
Relevance to Peptide Research
A significant proportion of research peptides target the GH axis. GHRH analogues (Sermorelin, CJC-1295, tesamorelin), growth hormone secretagogues (MK-677, GHRP-6, GHRP-2, ipamorelin, hexarelin), and somatostatin analogues (octreotide, lanreotide) all modulate GH physiology through different mechanisms. Understanding GH biology is foundational to interpreting research across these peptide categories.
Related Peptides
Peptide profiles that reference “Growth Hormone (GH)” in their research content.