Brain serotonin system in the coordination of food intake and body weight.

An inverse relationship between brain serotonin and food intake and body weight has been known for more than 30 years. Specifically, augmentation of brain serotonin inhibits food intake, while depletion of brain serotonin promotes hyperphagia and weight gain. Through the decades, serotonin receptors have been identified and their function in the serotonergic regulation of food intake clarified. Recent refined genetic studies now indicate that a primary mechanism through which serotonin influences appetite and body weight is via serotonin 2C receptor (5-HT(2C)R) and serotonin 1B receptor (5-HT(1B)R) influencing the activity of endogenous melanocortin receptor agonists and antagonists at the melanocortin 4 receptor (MC4R). However, other mechanisms are also possible and the challenge of future research is to delineate them in the complete elucidation of the complex neurocircuitry underlying the serotonergic control of appetite and body weight.