Evidence of gastrointestinal sensing and gut-brain communication in rainbow trout (Oncorhynchus mykiss) in response to the aqueous extract of fishmeal and its free amino acid fraction

Using rainbow trout (Oncorhynchus mykiss) as a model, we aimed to obtain information about the gastrointestinal tract (GIT) amino acid sensing capacity and hormone production along regions of GIT, in response proline (Pro), solution free acids (FAA) mimicking composition fishmeal (FM) aqueous extract (FM-FAA), or whole FM (FM-AQE). In addition, evaluated central responses (in hypothalamus) mechanisms regulating food intake, 2 h following intragastric administration these treatments. The presence Pro GIT elicited changes systems hormones, especially more proximal parallel with an anorectic hypothalamus. FM-AQE induced increased hormones peptide tyrosine-tyrosine (PYY) cholecystokinin (CCK) that occurred 20 min post-treatment middle intestine this treatment. These hypothalamus post-treatment. treatment FM-FAA comparable at post-treatment, which was associated however complex GIT. This included PYY CCK intestine, but also decreased orexigenic ghrelin (GHRL) stomach, after administration. effects were accompanied by some parameters related mediated receptors, not observed Overall, results indicate all treatments elements gut gut-brain axis, despite important differences specific genes (likely having different substrate specificities), areas times observed.