Impact on cerebral function in rainbow trout fed with plant based omega-3 long chain polyunsaturated fatty acids enriched with DHA and EPA
FISH & SHELLFISH IMMUNOLOGY
Authors: Roy, Jerome; Larroquet, Laurence; Surget, Anne; Lanuque, Anthony; Sandres, Franck; Terrier, Frederic; Corraze, Genevieve; Lee, Jetty Chung-Yung; Skiba-Cassy, Sandrine
Abstract
Characterization and modulation of cerebral function by omega-3 long chain polyunsaturated fatty acids (omega-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 omega-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. omega-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 omega-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 omega-3 experimental diet. In conclusion, this study revealed that a diet rich in omega-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.
Two distinct ontogenies confer heterogeneity to mouse brain microglia
DEVELOPMENT
Authors: De, Shrutokirti; Van Deren, Donn; Peden, Eric; Hockin, Matt; Boulet, Anne; Titen, Simon; Capecchi, Mario R.
Abstract
Hoxb8 mutant mice show compulsive behavior similar to trichotillomania, a human obsessive-compulsive-spectrum disorder. The only Hoxb8 lineage-labeled cells in the brains of mice are microglia, suggesting that defective Hoxb8 microglia caused the disorder. What is the source of the Hoxb8 microglia? It has been posited that all microglia progenitors arise at embryonic day (E) 7.5 during yolk sac hematopoiesis, and colonize the brain at E9.5. In contrast, we show the presence of two microglia subpopulations: canonical, non-Hoxb8 microglia and Hoxb8 microglia. Unlike non-Hoxb8 microglia, Hoxb8 microglia progenitors appear to be generated during the second wave of yolk sac hematopoiesis, then detected in the aorto-gonad-mesonephros (AGM) and fetal liver, where they are greatly expanded, prior to infiltrating the E12.5 brain. Further, we demonstrate that Hoxb8 hematopoietic progenitor cells taken from fetal liver are competent to give rise to microglia in vivo. Although the two microglial subpopulations are very similar molecularly, and in their response to brain injury and participation in synaptic pruning, they show distinct brain distributions which might contribute to pathological specificity. Non-Hoxb8 microglia significantly outnumber Hoxb8 microglia, but they cannot compensate for the loss of Hoxb8 function in Hoxb8 microglia, suggesting further crucial differences between the two subpopulations.