Grant: Discovery Grants Program - Individual

In vertebrates, complex hormonal networks regulate feeding, energy homeostasis and growth. Hypothalamic factors such as neuropeptide Y (NPY), orexins and cocaine and amphetamine regulated transcript (CART) ultimately control these functions by either stimulating or decreasing appetite. Other hormones, in particular gastrointestinal hormones such as amylin and cholecystokinin are released in the circulation and reach the brain where they can modulate the actions of these central factors. Environmental factors (e.g. temperature) might also affect feeding and appetite-related factors. In addition, given the link between energy reserves and reproduction, these central feeding regulators might also be influenced by reproductive events and be important regulators of reproduction. To date, there is limited information on the endocrine regulation of feeding and energy metabolism in fish. The goal of this program is to identify the molecules and mechanisms regulating feeding in fish, to assess their interactions and to examine how they are modulated by environmental factors and reproductive events. We intend to characterize uninvestigated peptides, including orexin, CART and amylin in fish, with respect to their nature and their role in feeding and reproduction. Research will be conducted at various levels of organization, from molecular to the whole animal. Techniques used include brain stereotaxic injections followed by behavioral observations and molecular techniques such as cDNA cloning and gene expression studies. Research will focus on goldfish and marine fish species (e.g. cod, flounder and skate) that have not been investigated in the past. Developing a better understanding of how food intake and growth are regulated by hormonal and environmental factors in fish might prove especially important to the aquaculture industry. Also, this research could contribute to the comprehension of the mechanisms that rule states of dysregulation of energy homeostasis in mammals such as obesity.