title: Retinal gene expression and visually evoked behavior in diabetic long evans rats.
abstract: OBJECTIVE
  Patients with diabetic retinopathy may experience severe vision loss due to macular edema and neovascularization secondary to vascular abnormalities. However, before these abnormalities become apparent, there are functional deficits in contrast sensitivity, color perception, and dark adaptation. The goals of this study are to evaluate early changes (up to 3 months) in retinal gene expression, selected visual cycle proteins, and optokinetic tracking (OKT) in streptozotocin (STZ)-induced diabetic rats.
  
  
  METHODS
  Retinal gene expression in diabetic Long Evans rats was measured by whole genome microarray 7 days, 4 weeks, and 3 months after the onset of hyperglycemia. Select gene and protein changes were probed by polymerase chain reaction (PCR) and immunohistochemistry, respectively, and OKT thresholds were measured using a virtual optokinetics system.
  
  
  RESULTS
  Microarray analysis showed that the most consistently affected molecular and cellular functions were cell-to-cell signaling and interaction, cell death, cellular growth and proliferation, molecular transport, and cellular movement. Further analysis revealed reduced expression of several genes encoding visual cycle proteins including lecithin/retinol acyltransferase (LRAT), retinal pigment epithelium (RPE)-specific protein 65 kDa (RPE65), and RPE retinal G protein-coupled receptor (RGR). These molecular changes occurred simultaneously with a decrease in OKT thresholds by 4 weeks of diabetes. Immunohistochemistry revealed a decrease in RPE65 in the RPE layer of diabetic rats after 3 months of hyperglycemia.
  
  
  CONCLUSIONS
  The data presented here are further evidence that inner retinal cells are affected by hyperglycemia simultaneously with blood retinal barrier breakdown, suggesting that glial and neuronal dysfunction may underlie some of the early visual deficits in persons with diabetes.
authors.affiliation: Department of Biological Sciences, Allergan, Inc., Irvine, California 92612, USA. kirwin_stefanie@allergan.com
authors.forename: Stefanie J
authors.initials: SJ
authors.lastname: Kirwin
authors.forename: Suzanne T
authors.initials: ST
authors.lastname: Kanaly
authors.forename: Candice R
authors.initials: CR
authors.lastname: Hansen
authors.forename: Belinda J
authors.initials: BJ
authors.lastname: Cairns
authors.forename: Meina
authors.initials: M
authors.lastname: Ren
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Edelman
mesh_terms: D000818:Animals; D001813:Blood-Retinal Barrier; D002352:Carrier Proteins / Q000235:genetics; D003921:Diabetes Mellitus, Experimental / Q000235:genetics* / Q000503:physiopathology; D003930:Diabetic Retinopathy / Q000235:genetics* / Q000503:physiopathology; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005136:Eye Proteins / Q000235:genetics*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000502:physiology*; D007150:Immunohistochemistry; D008297:Male; D017120:Nystagmus, Optokinetic / Q000502:physiology; D020411:Oligonucleotide Array Sequence Analysis; D051381:Rats; D020318:Rats, Long-Evans; D060888:Real-Time Polymerase Chain Reaction; D043562:Receptors, G-Protein-Coupled / Q000235:genetics; D055213:Retinal Pigment Epithelium / Q000378:metabolism*; D019745:cis-trans-Isomerases; D000099178:Retinoid Isomerohydrolase
chemical_list: D002352:Carrier Proteins; D005136:Eye Proteins; D043562:Receptors, G-Protein-Coupled; D019745:cis-trans-Isomerases; D000099178:Retinoid Isomerohydrolase