Glial-neuronal interactions underlying fructose utilization in rat hippocampal slices.
Although fructose is commonly used as a sweetener, its effects on brain function are unclear. Using rat hippocampal slices, we found that fructose and mannose, like pyruvate, preserve ATP levels during 3-h of glucose deprivation. Similarly, fructose and mannose restored synaptic potentials (excitatory postsynaptic potential, EPSPs) depressed during glucose deprivation. However, restoration of synaptic responses was slow and only partial with fructose. EPSPs supported by mannose were inhibited by cytochalasin B (CCB), a glucose transport inhibitor, but were not inhibited by alpha-cyano-4-hydroxycinnamate (4-CIN), a monocarboxylate transport inhibitor, indicating that neurons use mannose via glucose transporters. In contrast, both CCB and 4-CIN depressed EPSPs supported by fructose, suggesting that fructose may be taken up by non-neuronal cells through CCB sensitive hexose transporters and metabolized to a monocarboxylate for subsequent use during neuronal respiration. Supporting this possibility, 20 minutes of oxygen deprivation in the presence of fructose resulted in functional and morphological deterioration whereas oxygen deprivation in the presence of glucose or mannose had minimal toxic effects. These results indicate that neuronal fructose utilization differs from glucose and mannose and likely involves release of monocarboxylates from glia.
Department of Psychiatry, Washington University School of Medicine, St. Louis, MO 63110, USA. Izumiy@wustl.edu
Y
Y
Izumi
C F
CF
Zorumski
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D015687:Cell Hypoxia; D003373:Coumaric Acids / Q000008:administration & dosage; D003571:Cytochalasin B / Q000008:administration & dosage; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D005632:Fructose / Q000378:metabolism*; D005947:Glucose / Q000172:deficiency / Q000378:metabolism; D051246:Glucose Transport Proteins, Facilitative / Q000037:antagonists & inhibitors; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D008358:Mannose / Q000378:metabolism*; D008839:Microelectrodes; D027501:Monocarboxylic Acid Transporters / Q000037:antagonists & inhibitors; D009457:Neuroglia / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism; D051381:Rats; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology
D003373:Coumaric Acids; D051246:Glucose Transport Proteins, Facilitative; D027501:Monocarboxylic Acid Transporters; C007175:alpha-cyano-4-hydroxycinnamate; D005632:Fructose; D003571:Cytochalasin B; D000255:Adenosine Triphosphate; D005947:Glucose; D008358:Mannose; D010100:Oxygen