Growth Hormone

Full name: Somatotropin (GH/hGH)

A 191-amino-acid single-chain peptide hormone produced and secreted by somatotroph cells of the anterior pituitary. Regulates body composition, cell reproduction, and metabolism. Stimulates IGF-1 production in the liver. Secreted in pulsatile fashion, primarily during deep sleep. Declines with age (~14% per decade after age 25), driving interest in GH-stimulating peptide protocols.