Impact on cerebral function in rainbow trout fed with plant based omega-3 long chain polyunsaturated fatty acids enriched with DHA and EPA.

Characterization and modulation of cerebral function by ω-3 long chain polyunsaturated fatty acids (ω-3 LC-PUFAs), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) enrichment in plant based-diet were studied in rainbow trout (Oncorhynchus mikyss). We hypothesized that ω-3 LC-PUFAs are involved in the regulation of cerebral function in fish. During nine weeks, we examined the growth performance of rainbow trout for three experimental plant based-diets containing distinct levels of EPA and DHA. Using RT-qPCR, we assessed mRNA genes related to feeding behavior regulated by the central nervous system of humans, rodents and fish. These include markers of neuropeptides, indicators of cellular specification, animal stress, oxidant status, cytokines and genes regulating animal behaviour. ω-3 LC-PUFAs enrichment decreased daily food intake and induced a simultaneous mRNA expression increase in orexigenic transcript npy peptide and a decrease in anorexigen transcript pomcA peptide in the hypothalamus. Overall transcript genes related to proinflammatory cytokines, inflammation, antioxidant status, cortisol pathway, serotoninergic pathways and dopaminergic pathways were down-regulated in the juveniles fed the high ω-3 LC-PUFAs diet. However, the mRNA expression of transcripts related to cell specification were down regulated, namely tmem119 markers of microglial cell in forebrain and midbrain, gfap markers of astrocyte in the midbrain, and rbfox3 markers of neurons in the midbrain and hindbrain in juveniles fed high ω-3 experimental diet. In conclusion, this study revealed that a diet rich in ω-3 LC-PUFAs affected a relatively high proportion of the brain function in juvenile rainbow trout through mechanisms comparable to those characterized previously in mammals.