title: Gap junction proteins in the light-damaged albino rat.
abstract: OBJECTIVE
  Changes in connexin expression are associated with many pathological conditions seen in animal models and in humans. We hypothesized that gap junctions are important mediators in tissue dysfunction and injury processes in the retina, and therefore, we investigated the pattern of connexin protein expression in the light-damaged albino rat eye.
  
  
  METHODS
  Adult Sprague-Dawley rats were exposed to intense light for 24 h. The animals were euthanized, and ocular tissue was harvested at 0 h, 6 h, 24 h, 48 h, and 7 days after light damage. The tissues were processed for immunohistochemistry and western blotting to analyze the expression of the gap junction proteins in the light-damaged condition compared to the non-light-damaged condition. Cell death was detected using the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) technique.
  
  
  RESULTS
  Intense light exposure caused increased TUNEL labeling of photoreceptor cells. Immunocytochemistry revealed that connexin 36 (Cx36) was significantly increased in the inner plexiform layer and Cx45 was significantly decreased in the light-damaged retina. The pattern of Cx36 and Cx45 labeling returned to normal 7 days after light damage. Cx43 significantly increased in the RPE and the choroid in the light-damaged tissue, and decreased but not significantly in the retina. This elevated Cx43 expression in the choroid colocalized with markers of nitration-related oxidative stress (nitrotyrosine) and inflammation (CD45 and ionized calcium-binding adaptor molecule-1) in the choroid.
  
  
  CONCLUSIONS
  The results suggest that connexins are regulated differently in the retina than in the choroid in response to photoreceptor damage. Changes in connexins, including Cx36, Cx43, and Cx45, may contribute to the damage process. Specifically, Cx43 was associated with inflammatory damage. Therefore, connexins may be candidate targets for treatment for ameliorating disease progression.
authors.affiliation: Department of Optometry and Vision Science, University of Auckland, Auckland, New Zealand ; New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand.
authors.forename: Cindy X
authors.initials: CX
authors.lastname: Guo
authors.affiliation: Department of Optometry and Vision Science, University of Auckland, Auckland, New Zealand.
authors.forename: Henry
authors.initials: H
authors.lastname: Tran
authors.affiliation: Department of Ophthalmology, University of Auckland, Auckland, New Zealand ; New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand.
authors.forename: Colin R
authors.initials: CR
authors.lastname: Green
authors.affiliation: Department of Ophthalmology, University of Auckland, Auckland, New Zealand ; New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand.
authors.forename: Helen V
authors.initials: HV
authors.lastname: Danesh-Meyer
authors.affiliation: Department of Optometry and Vision Science, University of Auckland, Auckland, New Zealand ; New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand.
authors.forename: Monica L
authors.initials: ML
authors.lastname: Acosta
mesh_terms: D000818:Animals; D015153:Blotting, Western; D016923:Cell Death / Q000528:radiation effects; D018031:Connexin 43 / Q000378:metabolism; D017630:Connexins / Q000378:metabolism*; D005123:Eye / Q000378:metabolism* / Q000473:pathology / Q000528:radiation effects*; D005260:Female; D020287:In Situ Nick-End Labeling; D008027:Light; D008264:Macrophages / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D008297:Male; D020419:Photoreceptor Cells, Vertebrate / Q000378:metabolism / Q000528:radiation effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D055213:Retinal Pigment Epithelium / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism; D000097004:Gap Junction delta-2 Protein
chemical_list: D018031:Connexin 43; D017630:Connexins; D014443:Tyrosine; D000097004:Gap Junction delta-2 Protein; C082920:connexin 45; C002744:3-nitrotyrosine