Appetite regulation is a complex mechanism that involves physiological, psychological, and environmental signals. Research on the physiological control of feeding has shown that it involves an elaborate interaction between orexigenic (appetite stimulating) and anorectic (appetite suppressing) hormones, neuropeptides, and nutrients. Interestingly, the action of many of these molecules is transduced through G protein-coupled receptors (GPCRs). GPCRs represent the largest family of membrane receptors. GPCRs that respond to feeding-related molecules initiate intracellular signaling cascades that ultimately promote or inhibit food intake. These GPCRs are the focus of numerous drug development studies as targeting these receptors have the potential to modulate satiety and improve glucose homeostasis. R&D Systems offers a wide variety of tools for investigating the role of GPCRs in feeding behavior.