title: Expression of glucose transporters in the prelaminar region of the optic-nerve head of the pig as determined by immunolabeling and tissue culture.
abstract: BACKGROUND
  To develop the use of cultured tissue of the prelaminar optic nerve of the pig to explore possible alterations of the astrocyte-axon metabolic pathways in glaucoma, we map the distribution of the glucose transporters GLUT1 and GLUT3 in fresh and cultured tissue.
  
  
  METHODS
  We monitor cell survival in cultures of the prelaminar optic-nerve tissue, measuring necrosis and apoptosis markers biochemically as well as morphologically, and establish the presence of the glucose transporters GLUT1 and GLUT3. We map the distribution of these transporters with immunolabeling in histological sections of the optic nerve using confocal and electronic transmission microscopy.
  
  
  RESULTS
  We find that the main death type in prelaminar culture is apoptosis. Caspase 7 staining reveals an increment in apoptosis from day 1 to day 4 and a reduction from day 4 to day 8. Western blotting for GLUT1 shows stability with increased culture time. CLSM micrographs locate GLUT1 in the columnar astrocytes and in the area of axonal bundles. Anti-GLUT3 predominantly labels axonal bundles. TEM immunolabeling with colloidal gold displays a very specific distribution of GLUT-1 in the membranes of vascular endothelial cells and in periaxonal astrocyte expansions. The GLUT-3 isoform is observed with TEM only in axons in the axonal bundles.
  
  
  CONCLUSIONS
  Tissue culture is suitable for apoptosis-induction experiments. The results suggest that glucose is transported to the axonal cleft intracytoplasmically and delivered to the cleft by GLUT1 transporters. As monocarboxylate transporters have been reported in the prelaminar region of the optic-nerve head, this area is likely to use both lactate and glucose as energy sources.
authors.affiliation: Department of Surgery (Ophthalmology), Faculty of Medicine, University of Granada, Granada, Spain.
authors.forename: F Javier
authors.initials: FJ
authors.lastname: Carreras
authors.affiliation: Department of Biochemistry and Molecular Biology II, Faculty of Pharmacy, University of Granada, Granada, Spain.
authors.forename: Carlos J
authors.initials: CJ
authors.lastname: Aranda
authors.affiliation: Center of Scientific Instrumentation, University of Granada, Granada, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Porcel
authors.affiliation: Division of Ophthalmology, Licinio de la Fuente University Hospital, Granada, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Rodriguez-Hurtado
authors.affiliation: Department of Biochemistry and Molecular Biology II, Faculty of Pharmacy, University of Granada, and Networked Biomedical Research Center for Hepatic and Digestive Diseases (CIBEREHD), Granada, Spain.
authors.forename: Olga
authors.initials: O
authors.lastname: Martínez-Agustin
authors.affiliation: Department of Pharmacology, Faculty of Pharmacy, University of Granada, and Networked Biomedical Research Center for Hepatic and Digestive Diseases (CIBEREHD), Granada, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Zarzuelo
mesh_terms: D000818:Animals; D017209:Apoptosis; D051272:Glucose Transporter Type 1 / Q000378:metabolism*; D051274:Glucose Transporter Type 3 / Q000378:metabolism*; D009898:Optic Disk / Q000378:metabolism*; D013552:Swine; D046509:Tissue Culture Techniques
chemical_list: D051272:Glucose Transporter Type 1; D051274:Glucose Transporter Type 3