Orexins are neuropeptides that are localized in neurons within the lateral hypothalamus and regulate feeding behavior. The lateral hypothalamus plays an important role in not only feeding but the central regulation of gut function. Along this line, accumulating evidence have shown that orexins acts in the central nervous system to regulate gastrointestinal functions. The purpose of this review is to summarize recent relevant findings on brain orexins and a digestive system, and discuss the pathophysiological roles of the peptides. Centrally administered orexin or endogenously released orexin in the brain potently stimulates gastric acid secretion in rats. The vagal cholinergic pathway is involved in the orexin-induced stimulation of acid secretion. Considering its stimulatory action on feeding, it should be hypothesized that orexin in the brain is a candidate mediator of cephalic phase gastric secretion. In addition, brain orexin may be involved in the development of depression and functional gastrointestinal disorders which are frequently accompanied with the inhibition of gut function, because lack of orexin action might induce the inhibition of gastric physiology and evoke depressive state. These evidence suggest that orexin in the brain would be a possible molecular target for the treatment of functional gastrointestinal disorders.
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The original publication is available at springerlink.com