Involvement of Taste Receptors in the Oro-Sensory Perception of Nutrients in Rainbow Trout (Oncorhynchus mykiss) Fed Diets with Different Fatty Acid Profiles

Abstract

Taste perception plays an important role in an animal’s detection of nutrients, conveying key dietary information, fundamental for its growth and survival. Because alternative terrestrial ingredients are known to affect the feeding of rainbow trout (RT, Oncorhynchus mikyss), we aimed to assess the importance of taste receptors in detection. Using self-feeders, we examined the feeding behavior (30 days of a feeding trial followed by 10 days of a preference trial) of RT fed with a commercial diet (C), vegetable diets supplemented with linseed oil (V1) or algal oil (V2). During the feeding trial those fed V2 decreased their food intake. The preference trial revealed that fish preferred V2 v. C and V1 v. V2 for fish which had consumed V1 and C during their feeding trial. Mechanistically, taste receptors were mainly expressed in taste organs and regulated by diet, which indicated the function of the taste receptors. Some taste receptors for fatty acids (such as the ffar receptor) and amino acids (such as the tasr receptor) were highly expressed in the RT tongue. While ffar2a transcripts were upregulated by vegetal diets in the tongue, ffar1 and ffar4, known for important roles in mammals, were very low expressed and not found in the RT genome, respectively. Overall findings show that RT displayed the fundamental mechanisms for oro-gustatory perception of nutrients related to different diet composition.

Detection and Modulation of Olfactory Sensing Receptors in Carnivorous Rainbow Trout (Oncorhynchus mykiss) Fed from First Feeding with Plant-Based Diet

“…In our study, the major difference in terms of nutrients was DHA (26.53%) present in FO of the C diet and replaced by alpha-linolenic acid (ALA; 28.24%) in the V diet. As we recently suggested for the gustatory system [15], the difference in the proportion of ω-3 PUFAs between the two dietary treatments could involve the regulation of olfactory sensing receptors influencing the feeding behavior of RT. In this study, some olfactory receptor-encoding genes display modulation of their expression regarding diet and/or feeding status and are found in the three main olfactory receptor families.…”

“…For the gustatory sensing system, our previous research assessed the detection and modulation of taste receptors in RT fed with a total plant based-diet, with or without supplementation by ω-3 LC-PUFA [15]. The results of this study showed that RT have the fundamental mechanisms for oro-gustatory perception of nutrients related to different diet composition.…”

Long-term regulation of fat sensing in rainbow trout (Oncorhynchus mykiss) fed a vegetable diet from the first feeding: focus on free fatty acid receptors and their signalling

“…We postulate that the fish underwent adaptations to accommodate the provided diet, or alternatively, the juvenile fish were compelled to consume it in order to ensure their survival. In a recent study that included a similar formulation, we demonstrated that from the juvenile stage, RT had no preference for a commercial (with DHA and EPA) or plant-based (with ALA but without DHA and EPA) diet using a self-feeder method (17) . Thus, we were interested in the postprandial regulation of FI in RT fed the V diet over the long term.…”

“…Thus, beyond a purely neuropeptide regulation, the influence of FI could be related more to hedonic sensations of the diet. A previous study based on the same trial (17) indicated that changes in the FI of the V diet are related to a decrease in desire to eat rather than changes in the mechanisms of FI (i.e. regulation of appetite neuropeptide).…”

Physical Enrichment Triggers Brain Plasticity and Influences Blood Plasma Circulating miRNA in Rainbow Trout (Oncorhynchus mykiss)

“…Compared to 18 s and actin , the elongation factor 1α gene ( eef1α ) showed the most stable expression between brain areas and tissues and was chosen as the reference gene. Relative expression of the target genes was determined by the ΔΔCT method [ 35 , 36 , 37 ]. Mean ± standard error of mean values for each group are expressed in fold changes relative to the BE treatment for all genes.…”