Postnatal prebiotic supplementation in rats affects adult anxious behaviour, hippocampus, electrophysiology, metabolomics, and gut microbiota.

We have shown previously that prebiotic (Bimuno galacto-oligosacharides, B-GOS®) administration to neonatal rats increased hippocampal NMDAR proteins. The present study has investigated the effects of postnatal B-GOS® supplementation on hippocampus-dependent behavior in young, adolescent, and adult rats and applied electrophysiological, metabolomic and metagenomic analyses to explore potential underlying mechanisms. The administration of B-GOS® to suckling, but not post-weaned, rats reduced anxious behavior until adulthood. Neonatal prebiotic intake also reduced the fast decay component of hippocampal NMDAR currents, altered age-specific trajectories of the brain, intestinal, and liver metabolomes, and reduced abundance of fecal Enterococcus and Dorea bacteria. Our data are the first to show that prebiotic administration to rats during a specific postnatal period has long-term effects on behavior and hippocampal physiology. The study also suggests that early-life prebiotic intake may affect host brain function through the reduction of stress-related gut bacteria rather than increasing the proliferation of beneficial microbes.

Developmental Signatures of Microbiota-Derived Metabolites in the Mouse Brain.

The gut microbiome is recognized to exert a wide-ranging influence on host health and disease, including brain development and behavior. Commensal bacteria can produce bioactive molecules that enter the circulation and impact host physiology and homeostasis. However, little is known about the potential for these metabolites to cross the blood-brain barrier and enter the developing brain under normal physiological conditions. In this study, we used a liquid chromatography-mass spectrometry-based metabolomic approach to characterize the developmental profiles of microbial-derived metabolites in the forebrains of mice across three key postnatal developmental stages, co-occurring with the maturation of the gut microbiota. We demonstrate that direct metabolites of the gut microbiome (e.g., imidazole propionate) or products of the combinatorial metabolism between the microbiome and host (e.g., 3-indoxyl-sulfate, trimethylamine-N-oxide, and phenylacetylglycine) are present in the forebrains of mice as early as the neonatal period and remain into adulthood. These findings demonstrate that microbial-associated molecules can cross the BBB either in their detected form or as precursor molecules that undergo further processing in the brain. These chemical messengers are able to bind receptors known to be expressed in the brain. Alterations in the gut microbiome may therefore influence neurodevelopmental trajectories via the regulation of these microbial-associated metabolites.

Phenotypic characterization of retinoic acid differentiated SH-SY5Y cells by transcriptional profiling.

Multiple genetic and environmental factors play a role in the development and progression of Parkinson's disease (PD). The main neuropathological hallmark of PD is the degeneration of dopaminergic (DAergic) neurons in the substantia nigra pars compacta. To study genetic and molecular contributors to the disease process, there is a great need for readily accessible cells with prominent DAergic features that can be used for reproducible in vitro cellular screening. Here, we investigated the molecular phenotype of retinoic acid (RA) differentiated SH-SY5Y cells using genome wide transcriptional profiling combined with gene ontology, transcription factor and molecular pathway analysis. We demonstrated that RA induces a general neuronal differentiation program in SH-SY5Y cells and that these cells develop a predominantly mature DAergic-like neurotransmitter phenotype. This phenotype is characterized by increased dopamine levels together with a substantial suppression of other neurotransmitter phenotypes, such as those for noradrenaline, acetylcholine, glutamate, serotonin and histamine. In addition, we show that RA differentiated SH-SY5Y cells express the dopamine and noradrenalin neurotransmitter transporters that are responsible for uptake of MPP(+), a well known DAergic cell toxicant. MPP(+) treatment alters mitochondrial activity according to its proposed cytotoxic effect in DAergic neurons. Taken together, RA differentiated SH-SY5Y cells have a DAergic-like phenotype, and provide a good cellular screening tool to find novel genes or compounds that affect cytotoxic processes that are associated with PD.