Abstract
Novel neuropeptides of G-protein coupled receptor (GPCR) ligands are shown to be localized in brain and play a range of physiological functions including feeding regulation. This review concerns some novel GPCR ligands of feeding regulating neuropeptides such as orexin, ghrelin, galanin-like peptide (GALP) and neuropeptide W such as those studied by our research group, and neuronal interactions among these neuropeptides in the hypothalamus. Cross-talk among several these neuropeptides-containing neurons in the hypothalamus plays a key role in determining feeding states as well as feeding behavior. We will show some structural and functional characteristics of these novel GPCR ligands and summarize the interactions between these different kind of feeding regulating neurons and leptin-targeting neurons in brain. Moreover, we will present a new strategy for analyzing the neural circuit of these feeding-regulating GPCR ligands-containing neurons in brain by use of transgenic model mice. Finally, we will present our very recent results of GALP which are involved in regulation of feeding as well as energy homeostasis and body temperature. Research in this field will serve a very important role of clarifying neurologically-based causes for appetite dysfunctions and diseases and it may help in establishing and leading to new therapies for people who are suffering such conditions. [J Physiol Sci. 2008;58 Suppl:S15]
