HealthMap

Ghrelin and Hunger Signaling

• Primary Role: Ghrelin is widely known and documented in biochemical literature as the primary peptide hormone that stimulates appetite and initiates hunger signals.
• Site of Production: It is predominantly produced and released mainly by the stomach (specifically by oxyntic cells in the gastric fundus), although smaller amounts are also secreted by the small intestine, pancreas, and brain.
• Mechanism of Action:
• Circulating ghrelin acts on the hypothalamus in the brain, specifically targeting neuropeptide Y (NPY) and agouti-related peptide (AgRP) neurons.
• This neural activation generates the subjective sensation of hunger and promotes food intake.
• Physiological Fluctuation:
• Blood levels of ghrelin typically rise significantly before meals, anticipating energy intake.
• Levels drop sharply after eating as the stomach is distended and nutrients are processed.
• Broader Metabolic Impact: Beyond stimulating appetite, ghrelin also plays a crucial role in regulating growth hormone release, gastric motility, acid secretion, and long-term body weight regulation through energy homeostasis.