Role of neurotransmitters in obesity regulation

The main goal of this chapter is to provide a comprehensive review of neurotransmitters, neuropeptides, and other chemicals that have been reported to be involved in obesity regulation based on data obtained from animal and human studies. These substances affect obesity via several mechanisms: a decrease in food intake through satiety and non-satiety pathways or an effect on energy expenditure through hyperactivity and thermogenesis. An induction of weight loss is a resultant action of the ingestion of compounds that mimic or alter the action of neurotransmitters and neuropeptides, as described in this chapter. The neurotransmitters discussed in this chapter include 5-hydroxytryptamine (5-HT), or serotonin; the catecholamines norepinephrine (NE) and dopamine (DA); and histamine. For neuropeptides, the focus is on neuropeptide Y (NPY), galanin, corticotropin- releasing factor (CRF), orexin, and melanocortin. For both neurotransmitters and neuropeptides, an additional review of pharmacological receptors associated with their actions is provided. For brevity, only in highly relevant cases is a discussion of signal transduction pathways for neurotransmitters and neuropeptides included. We also discuss the role of other chemicals such as endocannabinoids and their respective receptors in the regulation of obesity. The reader is also provided with a bibliography of critical references for more information about the neurotransmitters and neuropeptides discussed in this chapter.