The central melanocortin system and the regulation of energy balance.

The central melanocortin system is comprised of discrete populations of neurons and circuits that play a key role in maintaining energy balance. This system can sense levels of peripheral energy stores and can integrate a variety of nutrient, neuronal and hormonal signals to regulate food intake, energy expenditure and nutrient metabolism. Disruption of this system at multiple levels causes obesity in humans and animals. This article reviews the normal physiology and regulation of the central melanocortin system, the abnormalities of this system that cause impaired energy balance in humans and in rodents and the potential to target this system for the treatment of obesity and cachexia.