Physiology, Obesity Neurohormonal Appetite And Satiety Control

Excerpt

The feelings of appetite and satiety involve complex interactions between hormones from the gastrointestinal tract to the hypothalamus and subsequent feedback. Within the hypothalamus are specific regions where hormones interact to produce sensations of appetite and satiety, leading to food consumption or a feeling of fullness. Through the interactions of ghrelin and leptin, the hypothalamus can regulate the sensation of hunger and satiety, leading to energy homeostasis. Ghrelin, termed the "hunger hormone," was initially discovered through its receptor, the growth hormone secretagogue receptor, before explaining its role as a growth-hormone-releasing peptide.

Leptin was discovered primarily as a signal in regulating body weight. However, the roles of these hormones in regulating appetite and satiety were not explicitly known until research showed a correlation between a rise in plasma levels of ghrelin before meals and a subsequent decrease in plasma levels of ghrelin after meals and a subsequent change in plasma leptin levels. Together, ghrelin and leptin signals regulate our sensations of hunger and satiety by sending signals to different nuclei within the hypothalamus for food intake. An imbalance or dysregulation of these hormones may drastically affect the body's energy homeostasis.