Influence of the environment on feeding from a fish point of view

DI YORIO, MARÍA P.

Mar del Plata

Congreso; Reunión conjunta SAIC SAB AAFE AACYTAL 2023. XXV Jornadas Anuales de la Sociedad Argentina de Biología (SAB).; 2023

SAIC SAB AAFE AACYTAL

Teleost fish represent more than half of the extant vertebrate species. This group is characterized by a remarkable diversity in terms of genome, ecology, behavior, and anatomy. Besides, their feeding habits range from herbivore to carnivore, resulting in high variability of the gastrointestinal tract (GIT) morphology and hormone profiles. Food intake and feeding behavior are regulated by the interaction between the central nervous system and the GIT in conjunction with the associated organs (pancreas, liver, gall bladder), which synthesize neuropeptides and hormones similar to those that control this function in other groups of vertebrates. Although these neuropeptides and peptides are found throughout the vertebrate lineage, some functions would be conserved while others depend on the group studied. This fact makes them attractive for studying the evolution of appetite-regulating systems. At the central level, the main center that regulates food intake is in the hypothalamus, where different populations of neurons produce important neuropeptides: neuropeptide Y (Npy) / agouti-related peptide (Agrp), proopiomelanocortin (POMC), melanocyte-stimulating hormone (Mch), orexins, and cocaine- and amphetamine-regulated transcript (Cart). Besides, the main hormones produced by the GIT are ghrelin (secreted by the stomach or its equivalent in fish species that do not have it); cholecystokinin (Cck, synthesized by cells of the gastrointestinal tract); neuropeptide Y (Npy), and peptide yy (Pyy) (produced by endocrine cells of the intestine); insulin, and glucagon (produced by pancreatic cells) and leptin (secreted mainly by the liver). These peptides exert different actions at the local level, promoting the secretion of digestive enzymes, motility, or absorptive capacity, and in turn, enter the bloodstream and modulate the expression of neuropeptides at the central level. Besides, this network, which involves the neuroendocrine and endocrine cells mentioned above sense internal (such as reproductive and nutritional status, or stress) and external factors (such as temperature, photoperiod, light, hypoxia, salinity, social status, nutrients, or GIT microbiota/parasites), which in turn modulate food intake and the characteristics of the GIT, "adjusting" these functions to the demands of the organism. Thus, knowing how these neuropeptides and peptides act is essential to understand how different internal and external factors impact on the regulation of food intake in teleost fish, and it will also help maximize production efficiency in aquaculture. Considering that new actors have been included in this network, this presentation will summarize the current knowledge of the hypothalamic-GIT network, discuss the impact of external and internal factors, and the gaps that are necessary to access this complex and dynamic system. In this frame, we will present results obtained in the cichlid fish Cichlasoma dimerus about a new factor and the impact of tank color.