Project summary: The major goal of this research proposal is to elucidate the function of serotonin (5-HT) in feeding and feeding-related behaviors in Drosophila melanogaster. 5-HT affects the feeding behavior of both vertebrates and invertebrates, however the precise molecular mechanisms by which this occurs are largely unknown. 5-HT also influences numerous other behaviors and physiological processes that could affect feeding such as locomotion, circadian rhythm and digestion. Using the genetically tractable fruit fly, I will address the following questions: How does 5-HT affect both feeding and other feeding-related behaviors? Are there specific subpopulations of 5-HT neurons that affect feeding directly? What is the role of the serotonin receptors in these behaviors? I will address these questions with the following specific aims: Aim 1. Loss-of-function and gain-of-function manipulations of 5-HT signaling. Aim 2. Identification and characterization of 5-HT neuronal subsets. Aim 3. Analysis of 5-HT receptors in feeding behavior. Relevance to public health: Obesity is a serious health concern that confronts millions of people worldwide. In the U.S., more than 65% of adults and 15% of children are considered overweight. Exploration of feeding behavior in model organisms will promote our understanding of how complex behavioral states, such as hunger and satiety, are controlled in the nervous system. [unreadable] [unreadable] [unreadable]