Overviews of avian neuropeptides and peptides

Abstract Peptides play significant roles in diverse physiological processes. This chapter provides a brief review on 134 peptides/neuropeptides, divided under 39 families. This covers their structure, functions, expression and major actions involved in the regulation of avian growth, stress, food intake, energy balance, lipid and glucose metabolism, reproduction, water homeostasis, calcium homeostasis, cardiovascular functions, blood pressure, host defense, etc., in a systemic approach. Most of these avian peptides have their corresponding mammalian orthologs, and some of them play physiological roles similar to those in mammals, such as hypothalamic GHRH and SST, stimulate, and inhibit pituitary GH secretion, respectively. However, notable differences are present between these two animal groups, so caution must be taken when we transfer our knowledge on mammalian peptides onto avian models. The unique physiological and behavioral processes such as flight, brooding in birds warrant in-depth investigation to uncover the roles of these peptides in avian model and across vertebrates from a comparative endocrinological perspective.