title: Diurnal rodents as animal models of human central vision: characterisation of the retina of the sand rat Psammomys obsesus.
abstract: BACKGROUND
  Cone photoreceptor-based central vision is of paramount importance in human eyesight, and the increasing numbers of persons affected by macular degeneration emphasizes the need for relevant and amenable animal models. Although laboratory mice and rats have provided valuable information on retinal diseases, they have inherent limitations for studies on macular pathology. In the present study, we extend our recent analyses of diurnal murid rodents to demonstrate that the sand rat Psammomys obesus has a remarkably cone-rich retina, and represents a useful adjunct to available animal models of central vision.
  
  
  METHODS
  Adult P. obesus were captured and transferred to animal facilities where they were maintained under standard light/dark cycles. Animals were euthanised and their eyes enucleated. Tissue was either fixed in paraformaldehyde and prepared for immunohistochemistry, or solubilized in lysis buffer and separated by SDS-PAGE and subjected to western blot analysis. Samples were labelled with a battery of antibodies against rod and cone photoreceptors, inner retinal neurones, and glia.
  
  
  RESULTS
  P. obesus showed a high percentage of cones, 41% of total photoreceptor numbers in both central and peripheral retina. They expressed multiple cone-specific proteins, including short and medium-wavelength opsin and cone transducin. A second remarkable feature of the retina concerned the horizontal cells, which expressed high levels of glial fibrillar acidic protein and occludin, two proteins which are not seen in other species.
  
  
  CONCLUSIONS
  The retina of P. obesus displays high numbers of morphologically and immunologically identifiable cones which will facilitate analysis of cone pathophysiology in this species. The unusual horizontal cell phenotype may be related to the cone distribution or to an alternative facet of the animals lifestyle.
authors.affiliation: Département de Neurobiologie des Rythmes, CNRS UPR 3212 Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, 5 rue Blaise Pascal, 67084, Strasbourg Cedex, France.
authors.forename: Tounès
authors.initials: T
authors.lastname: Saïdi
authors.forename: Sihem
authors.initials: S
authors.lastname: Mbarek
authors.forename: Rafika Ben
authors.initials: RB
authors.lastname: Chaouacha-Chekir
authors.forename: David
authors.initials: D
authors.lastname: Hicks
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D015153:Blotting, Western; D002452:Cell Count; D002940:Circadian Rhythm / Q000502:physiology*; D004591:Electrophoresis, Polyacrylamide Gel; D005136:Eye Proteins / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D005849:Gerbillinae / Q000033:anatomy & histology*; D023421:Models, Animal; D009457:Neuroglia / Q000166:cytology / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D017949:Retinal Cone Photoreceptor Cells / Q000166:cytology* / Q000378:metabolism; D055351:Retinal Neurons / Q000166:cytology / Q000378:metabolism; D017948:Retinal Rod Photoreceptor Cells / Q000166:cytology* / Q000378:metabolism; D014785:Vision, Ocular / Q000502:physiology*
chemical_list: D015415:Biomarkers; D005136:Eye Proteins