💉
Endocrine
Vertebrates
Growth Hormone / IGF-1 Axis
GH-driven somatic growth and metabolism via hepatic IGF-1 production.
Overview
Growth hormone (GH) is secreted from the anterior pituitary in pulsatile fashion, regulated by hypothalamic GHRH (stimulatory) and somatostatin (inhibitory). GH binds GH receptor (GHR), a cytokine receptor family member, activating JAK2-STAT5 signaling. GH stimulates hepatic IGF-1 production, which mediates most growth-promoting effects through IGF-1R (a receptor tyrosine kinase) activating PI3K-AKT and RAS-MAPK pathways.
Cellular Location
Hypothalamus → Pituitary → Liver → Systemic
Clinical Significance
GH deficiency causes dwarfism (recombinant GH therapy); GH excess causes gigantism/acromegaly; IGF-1 pathway linked to aging (caloric restriction reduces IGF-1); IGF-1R targeted in cancer trials.