The endocrine regulation of feeding in fish

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In all vertebrates, the regulation of food intake involves intricate networks of appetite-regulating factors (ARFs) produced by both brain and peripheral tissues. ARFs affect feeding centres in the brain, and either stimulate or inhibit feeding. Despite recent advances, our current understanding of the regulation of feeding in fish is limited and based on few model species, e.g. goldfish. However, the diversity in species and diets/feeding habits in fish suggests the existence of species-specific mechanisms in the endocrine regulation of feeding. My research has established comprehensive and interactive models of feeding control in fish by examining ARFs in several marine (i.e. cunner and skate) and freshwater (i.e. goldfish, characids) fish. The ongoing long-term goal of my research is to identify and characterize molecules and physiological mechanisms regulating appetite and food intake in fish, and to examine how they are modulated by nutritional status, diet, environmental cues and reproductive events. To date, my research has provided compelling new evidence that major interspecific differences occur in the structure, sites of production and mechanisms of action of these factors. My program is unique in that it is one of the few worldwide to use an integrative (from whole animal to genes) comparative approach to examine the endocrine regulation of feeding in both freshwater and marine fish. We also use a variety of complementary techniques, which include in vivo (injections, behavioral observations) and in vitro (cloning, qPCR, RNAseq, tissue culture, enzyme assays, in situ hybridization) methods. Our short-term objectives are to: (1) characterize ARFs in temperate and tropical fish and assess the interactions between ARFs (2) examine the effects of fasting, diets and exercise on feeding and ARFs; (3) examine the interactions between gut microbiota and ARFs; (4) examine the effects of environmental changes and potential climate change-induced variations on feeding and ARFs; (5) assess the interactions of ARFs in the regulation of feeding and reproduction. This research will allow us to establish a general model elucidating the endocrine regulation of feeding in fish and vertebrates and its impact on growth and reproduction, provide new approaches to manage and enhance growth and reproduction in fish and to understand how different fish species deal with environmental stressors of ecological importance (e.g. global warming). Our results will be highly beneficial and likely to have impact in the local and multi-national fishing and aquaculture industries.