Figure 1.

A schematic model for functional segregation of the central melanocortin system. Current evidence suggests that several subsets of POMC neurons exist in the ARC that project to and act on distinct downstream MC4R populations to suppress food intake, to increase energy expenditure, to decrease insulin secretion, or to increase insulin sensitivity, respectively. Multiple metabolic cues, including estrogens, 5-HT, and leptin, directly act on distinct or partially overlapping POMC subsets to regulate different aspects of energy and glucose homeostasis.