title: Oxidative stress increases in retinas of dogs in acute glaucoma but not in chronic glaucoma.
abstract: OBJECTIVE
  To test the hypothesis that oxidative stress occurs early in the pathogenesis of glaucoma in dogs.
  
  
  METHODS
  Sections from eight control retinas and 25 retinas from dogs with primary glaucoma.
  
  
  METHODS
  For retinas embedded in paraffin, sections were immunohistochemically stained for malondialdehyde (MDA) and 3-nitrotyrosine (NT). For retinas embedded in plastic, serial 0.5-μm sections were immunogold-stained for total glutathione, taurine, and glutamate.
  
  
  RESULTS
  Increased immunostaining for MDA and NT, markers of oxidative stress, occurred in retinal ganglion cells (RGCs) and other neurons in acute glaucoma, but not in chronic glaucoma. In minimally damaged regions, immunostaining for the antioxidant glutathione was decreased in RGCs, neurons of the inner nuclear layer (INL), and Müller cell processes. The loss of glutathione immunostaining in RGCs occurred without a decrease in glutamate immunostaining. Neurons with nuclear damage in the INL had low levels of glutathione, taurine, and glutamate. In severely damaged regions, immunostaining for glutathione was increased in the remaining retinal tissue.
  
  
  CONCLUSIONS
  Immunohistochemical staining revealed an increase in markers of oxidative stress and loss of glutathione in neurons with minimal damage during acute glaucoma. Oxidative changes were no longer present in chronic glaucomatous retinas, suggesting transient oxidative stress occurs early in glaucoma. The loss of glutathione in minimally damaged regions occurred without a significant redistribution of glutamate, suggesting oxidative stress may occur before glutamate redistribution. Alteration in markers of oxidative stress occurs early in canine glaucoma, suggesting oxidative stress may contribute to subsequent glutamate redistribution and other damaging processes.
authors.affiliation: Department of Clinical Sciences, Colorado State University, Fort Collins, Colorado.
authors.forename: Thomas
authors.initials: T
authors.lastname: Chen
authors.affiliation: Department of Clinical Sciences, Colorado State University, Fort Collins, Colorado.
authors.forename: Juliet R
authors.initials: JR
authors.lastname: Gionfriddo
authors.affiliation: Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado.
authors.forename: Pei-Yi
authors.initials: PY
authors.lastname: Tai
authors.affiliation: Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado.
authors.forename: Anna N
authors.initials: AN
authors.lastname: Novakowski
authors.affiliation: College of Medicine, King Saud University, Riyadh, Saudi Arabia.
authors.forename: Khaleel
authors.initials: K
authors.lastname: Alyahya
authors.affiliation: Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado.
authors.forename: James E
authors.initials: JE
authors.lastname: Madl
mesh_terms: D000208:Acute Disease; D000818:Animals; D016022:Case-Control Studies; D002908:Chronic Disease; D004283:Dog Diseases / Q000378:metabolism* / Q000473:pathology; D004285:Dogs; D063928:Ependymoglial Cells / Q000378:metabolism / Q000473:pathology; D005901:Glaucoma / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D005978:Glutathione / Q000378:metabolism; D018384:Oxidative Stress; D012160:Retina / Q000378:metabolism* / Q000473:pathology
chemical_list: D005978:Glutathione
keywords: dogs; glaucoma; glutamate; glutathione; malondialdehyde; oxidative stress