Feeding the developing brain: Juvenile rats fed diet rich in prebiotics and bioactive milk fractions exhibit reduced anxiety-related behavior and modified gene expression in emotion circuits

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Early life nutrition is critical for brain development. Dietary prebiotics and bioactive milk fractions support brain development by increasing plasticity and altering activity in brain regions important for cognition and emotion regulation, perhaps through the gut-microbiome-brain axis. Here we examined the impact of a diet containing prebiotics, lactoferrin, and milk fat globule membrane (test diet) on beneficial gut bacteria, basal gene expression for activity and plasticity markers within brain circuits important for cognition and anxiety, and anxiety-related behavior in the open field. Juvenile male F344 rats were fed the test diet or a calorically matched control diet beginning postnatal day 24. After 4 weeks on diets, rats were sacrificed and brains were removed. Test diet significantly increased mRNA expression for cfos, brain derived neurotropic factor, and the GluN1 subunit of the NMDA receptor in the prefrontal cortex and reduced cfos mRNA within the amygdala. Diet-induced increases in fecal Lactobacillus spp., measured using selective bacterial culture, positively correlated with altered gene expression for cfos and serotonin receptors within multiple brain regions. In a separate cohort of juvenile rats, 4 weeks of the test diet increased time spent in the center of the open field, a behavior indicative of reduced anxiety. These data demonstrate that early life diets containing prebiotics and bioactive milk fractions can adaptively alter genes in neural circuits underlying emotion regulation and impact anxiety-related behavior.