The design of more efficient feeding strategies is one of the major challenges facing aquaculture when it comes to producing fish, a source of high-quality proteins for a growing human population, and which extractive fishing is unable to meet. “The most important cost of fish production is food. Knowing the mechanisms that make a fish eat or not eat will allow us to design more efficient feeding strategies in the medium term, so that the fish eat all the food at the optimal time and conditions for it, so that none of it is wasted,” explains José Luis Soengas, a professor and researcher in the Fish Physiology group at the Marine Research Center (CIM), who, together with his groupmate Jesús Míguez, coordinates the project New perspectives on the regulation of food intake in fish: interactions between homeostatic, circadian and hedonic mechanisms. With a total amount of around 600,000 euros, the project of the State R&D&I Program Oriented to the Challenges of Society of the Ministry of Science and Innovation, has the participation, in addition to researchers from UVigo, of the Fish Neuroendocrinology group of the Complutense University, led by María Jesús Delgado and the Fish Intake Control group of the Torre de la Sal Aquaculture Institute-CSIC with José Miguel Cerdá-Reverter at the head.
There are three basic components in the regulation of food intake in fish: homeostatic regulation, mediated by metabolic and endocrine mechanisms and which explains the mechanisms of hunger and satiety; circadian regulation, which explains why some animals eat during the day and others at night; and hedonic regulation, which explains why an animal eats even when it is not hungry. The three subprojects that make up this research address the three basic components in the regulation of intake in a series of joint or separate experimental tasks. “In this new project, using several species of teleost fish as a model, the participants, coordinated by the University of Vigo, intend to go one step further in the knowledge of the processes that regulate food intake, delving into not only the homeostatic and circadian mechanisms, studied to date, but also the hedonic or reward mechanisms, which have not been addressed in detail by any research group to date”, details Soengas, whose research group has been collaborating with the other members of the project for 15 years on homeostatic and circadian regulations. Regarding hedonic regulation, the UVigo researcher points out that although it is well known that fish can eat when they are not hungry, “so it is assumed that this hedonic regulation of intake exists in them”, the specific knowledge of it, that is, which food components would stimulate it, through which mechanisms, or in which places, etc. “is something that there is very little knowledge of”.
Research teams that established the scientific basis of ingestion mechanisms
The three research teams participating in the project New perspectives on the regulation of food intake in fish: interactions between homeostatic, circadian and hedonic mechanisms have previously worked together in five coordinated and consecutive projects over the last 15 years, “which allowed us to establish the scientific bases of the mechanisms of intake, as evidenced by the large number of JCR articles, approximately 200 in the last 10 years, and above all the quality, the majority Q1, which is why they are an international reference in this regard”, points out Soengas, who in the medium term hopes that the transfer of the project results to the production sector will allow improving the design of feeding strategies in aquaculture “and, consequently, contribute to strengthening its competitiveness and sustainability”.
In the project, which began in the middle of this year and will last until the middle of 2023, at the homeostatic level, the objectives addressed include, at the gastrointestinal level, characterizing the capacity to detect nutrients and their participation through the modulation of the secretion of gastrointestinal hormones in the control of food intake, as well as the impact of the overexpression of the neuropeptide ASIP and the mechanisms of action of serotonin at both the central and peripheral levels. “The research staff will characterize the regulatory role in food intake and energy expenditure of new peripheral regulatory peptides such as asprosin, adropin and phenexin,” explains Soengas, who in the case of the regulation of peripheral metabolism explains that the effect of alterations at the central level in AMPK (AMP-activated protein kinase) will be studied, as well as the role of nocturnin in the liver. At a central level, aspects of nutrient detection mechanisms that have not been studied to date will be addressed, such as sexual dimorphism or new intracellular mechanisms, and, secondly, the mechanisms of nutrient and hormone integration will be studied.
At the circadian level, the objectives set will allow determining the rhythmicity of the melanocortin system, evaluating the capacity of hepatic clocks for the integration of endocrine and light signals, characterizing new clocks at the central level and their relationship with peripheral clocks, determining the role of energy sensors in the functioning of endogenous clocks, the possible synchronization role of intestinal microbiota metabolites or the capacity of the serotonergic system to modulate circadian oscillators. Finally, at the hedonic level, the behavioral tests for their study will be defined, the presence of possible hedonic components in food and their communication pathways to the central nervous system will be evaluated, and the possible circadian dependence of hedonic responses and possible mediators of them will be characterized.
The research activity of the CIM has the support of the Xunta de Galicia and the European Union, through its co-financing under the FEDER/FSE Galicia 2014-2020 Operational Program.
Source: DUVI
