title: Metabolite transport across the mammalian and insect brain diffusion barriers.
abstract: The nervous system in higher vertebrates is separated from the circulation by a layer of specialized endothelial cells. It protects the sensitive neurons from harmful blood-derived substances, high and fluctuating ion concentrations, xenobiotics or even pathogens. To this end, the brain endothelial cells and their interlinking tight junctions build an efficient diffusion barrier. A structurally analogous diffusion barrier exists in insects, where glial cell layers separate the hemolymph from the neural cells. Both types of diffusion barriers, of course, also prevent influx of metabolites from the circulation. Because neuronal function consumes vast amounts of energy and necessitates influx of diverse substrates and metabolites, tightly regulated transport systems must ensure a constant metabolite supply. Here, we review the current knowledge about transport systems that carry key metabolites, amino acids, lipids and carbohydrates into the vertebrate and Drosophila brain and how this transport is regulated. Blood-brain and hemolymph-brain transport functions are conserved and we can thus use a simple, genetically accessible model system to learn more about features and dynamics of metabolite transport into the brain.
authors.affiliation: Institut für Neuro- und Verhaltensbiologie, Universität Münster, Badestr. 9, 48149 Münster, Germany.
authors.forename: Astrid
authors.initials: A
authors.lastname: Weiler
authors.affiliation: Institut für Neuro- und Verhaltensbiologie, Universität Münster, Badestr. 9, 48149 Münster, Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Volkenhoff
authors.affiliation: Institut für Neuro- und Verhaltensbiologie, Universität Münster, Badestr. 9, 48149 Münster, Germany.
authors.forename: Helen
authors.initials: H
authors.lastname: Hertenstein
authors.affiliation: Institut für Neuro- und Verhaltensbiologie, Universität Münster, Badestr. 9, 48149 Münster, Germany. Electronic address: stefanie.schirmeier@wwu.de.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Schirmeier
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000502:physiology*; D001812:Blood-Brain Barrier / Q000378:metabolism*; D006458:Hemolymph / Q000378:metabolism*; D006801:Humans; D007313:Insecta; D008322:Mammals
keywords: Blood-brain barrier; Brain metabolism; Hemolymph-brain barrier; Metabolite transport