title: Increased levels of extracellular ATP in glaucomatous retinas: Possible role of the vesicular nucleotide transporter during the development of the pathology.
abstract: OBJECTIVE
  To study retinal extracellular ATP levels and to assess the changes in the vesicular nucleotide transporter (VNUT) expression in a murine model of glaucoma during the development of the disease.
  
  
  METHODS
  Retinas were obtained from glaucomatous DBA/2J mice at 3, 9, 15, and 22 months together with C57BL/6J mice used as age-matched controls. To study retinal nucleotide release, the retinas were dissected and prepared as flattened whole mounts and stimulated in Ringer buffer with or without 59 mM KCl. To investigate VNUT expression, sections of the mouse retinas were evaluated with immunohistochemistry and western blot analysis using newly developed antibodies against VNUT. All images were examined and photographed under confocal microscopy. Electroretinogram (ERG) recordings were performed on the C57BL/6J and DBA/2J mice to analyze the changes in the electrophysiological response; a decrease in the scotopic threshold response was observed in the 15-month-old DBA/2J mice.
  
  
  RESULTS
  In the 15-month-old control and glaucomatous mice, electrophysiological changes of 42% were observed. In addition, 50% increases in the intraocular pressure (IOP) were observed when the pathology was fully established. The responses in the retinal ATP net release as the pathology progressed varied from 0.32±0.04 pmol/retina (3 months) to 1.10±0.06 pmol/retina (15 months; threefold increase). Concomitantly, VNUT expression was significantly increased during glaucoma progression in the DBA/2J mice (58%) according to the immunohistochemical and western blot analysis.
  
  
  CONCLUSIONS
  These results may indicate a possible correlation between retinal dysfunction and increased levels of extracellular ATP and nucleotide transporter. These data support an excitotoxicity role for ATP via P2X7R in glaucoma. This modified cellular environment could contribute to explaining the functional and biochemical alterations observed during the development of the pathology.
authors.affiliation: Departamento de Bioquímica y Biología Molecular IV, Facultad Óptica, Universidad Complutense de Madrid, Madrid, Spain.
authors.forename: María J
authors.initials: MJ
authors.lastname: Pérez de Lara
authors.affiliation: Departamento de Bioquímica y Biología Molecular IV, Facultad Óptica, Universidad Complutense de Madrid, Madrid, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Guzmán-Aránguez
authors.affiliation: Departmento de Biología de Sistemas, Facultad de Medicina, Universidad de Alcalá, Alcalá de Henares, Spain.
authors.forename: Pedro
authors.initials: P
authors.lastname: de la Villa
authors.affiliation: Departamento de Bioquímica y Biología Molecular IV, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid, Spain.
authors.forename: Juan Ignacio
authors.initials: JI
authors.lastname: Díaz-Hernández
authors.affiliation: Departamento de Bioquímica y Biología Molecular IV, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid, Spain.
authors.forename: María Teresa
authors.initials: MT
authors.lastname: Miras-Portugal
authors.affiliation: Departamento de Bioquímica y Biología Molecular IV, Facultad Óptica, Universidad Complutense de Madrid, Madrid, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Pintor
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000375:Aging / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D004195:Disease Models, Animal; D018450:Disease Progression; D004596:Electroretinography; D005260:Female; D015870:Gene Expression; D005901:Glaucoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D007429:Intraocular Pressure; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D033704:Nucleotide Transport Proteins / Q000235:genetics / Q000378:metabolism*; D058486:Receptors, Purinergic P2X7 / Q000235:genetics / Q000378:metabolism; D012160:Retina / Q000378:metabolism* / Q000473:pathology; D014065:Tonometry, Ocular
chemical_list: D033704:Nucleotide Transport Proteins; D058486:Receptors, Purinergic P2X7; C578984:Slc17a9 protein, mouse; D000255:Adenosine Triphosphate