title: Extracellular ascorbate modulates glutamate dynamics: role of behavioral activation.
abstract: BACKGROUND
  A physiological increase in extracellular ascorbate (AA), an antioxidant vitamin found throughout the striatum, elevates extracellular glutamate (GLU). To determine the role of behavioral arousal in this interaction, microdialysis was used to measure striatal GLU efflux in rats tested in either a lights-off or lights-on condition while reverse dialysis either maintained the concentration of AA at 250 microM or increased it to 1000 microM to approximate endogenous changes.
  
  
  RESULTS
  When lights were off, both locomotion and GLU increased regardless of AA dose. In contrast, animals in the lights-on condition were behaviorally inactive, and infusion of 1000, but not 250, microM AA significantly increased extracellular GLU. Interestingly, when ambient light returned to the lights-off group, 1000 microM prolonged the GLU increase relative to the 250 microM group.
  
  
  CONCLUSIONS
  Our results not only support evidence that elevated striatal AA increases extracellular GLU but also indicate that this effect depends on behavioral state and the corresponding level of endogenous GLU release.
authors.affiliation: Central Michigan University, Psychology Department, Mount Pleasant, MI, USA. sands1m@cmich.edu <sands1m@cmich.edu>
authors.forename: Michael I
authors.initials: MI
authors.lastname: Sandstrom
authors.forename: George V
authors.initials: GV
authors.lastname: Rebec
mesh_terms: D000818:Animals; D001143:Arousal / Q000502:physiology*; D001205:Ascorbic Acid / Q000378:metabolism*; D001522:Behavior, Animal / Q000502:physiology*; D003342:Corpus Striatum / Q000502:physiology*; D018698:Glutamic Acid / Q000378:metabolism*; D008124:Locomotion / Q000502:physiology*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D018698:Glutamic Acid; D001205:Ascorbic Acid