[Physiology of appetite and feeding behavior: introduction]

Food intake is regulated by the central nervous system depending on macronutrients and environmental changes. The hypothalamus is the target of hunger and satiety signals arising from the peripheral organs and the brain. Noradrenaline-neuropeptide Y and opioid-galanine are involved in carbohydrate and fat intake, respectively, while serotonin-CCK-insulin and dopamine-cyclic dipeptides systems inhibit them. Histamine and proinflammatory cytokines are involved in stress- and sickness-induced anorexia. Leptin accelerated intrahypothalamic anorexic mechanisms executed by POMC/CART and CRH but suppresses orexigenic mechanisms promoted by NPY and orexin. Although these mechanisms elegantly regulate appetite and feeding behavior, disruption of weight control has been accelerated and the incidence of obesity and eating disorder are dramatically increasing recent years in our modern society. New approach may be necessary to solve the problems of weight control.