title: [Experimental studies of effects of retinoic acid on the proliferation of retinal cells].
abstract: OBJECTIVE
  To determine whether the application of exogenous retinoic acid (RA) may induce the proliferation of retinal cells in adult rat.
  
  
  METHODS
  Thirty-two healthy adult Sprague-Dawley (SD) rats were randomly divided into 4 groups. In Group 1 and Group 2, all-trans RA (5 microliter, 0.001 mol/L) was injected into the subretinal space. In Group 3 and Group 4, all-trans RA (10 microliter, 0.001 mol/L) was injected into epiretinal vitreous space. In the Group 1 and Group 3, transient ischemic-reperfusion injuries of the experimental eyes were induced by ligating ophthalmic artery prior to RA treatment. In the control group, 5 SD rats were treated by ischemia-reperfusion injuries but no exogenous RA application. The treated eyes were enucleated for light microscopic analysis and immunohistochemical assays after 2 - 4 weeks of RA application.
  
  
  RESULTS
  In group 1, the number of the retinal cells expressing rod-specific opsin marker in the subretinal space was significantly increased and the thickness of inner nuclear layer was also increased after the RA treatment for 16 days. However, no cell proliferation was detected in group 2. There were also no changes within population of retinal cells in Group 3 and Group 4 in which RA was injected into epiretinal vitreous space no matter under the ischemia-reperfusion or non-ischemia-reperfusion. In the control group, there were no significant morphological changes within the neural retinal layers as well as photoreceptor proliferation.
  
  
  CONCLUSIONS
  The application of RA in the subretinal space can induce photoreceptor proliferation in adult rat under an ischemic-reperfusion injury condition. It will provide a new idea for the regeneration of neural retinal cells.
authors.affiliation: Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China. shibotang@yahoo.com.cn
authors.forename: Shibo
authors.initials: S
authors.lastname: Tang
authors.forename: Guanting
authors.initials: G
authors.lastname: Qiu
authors.forename: Zhixiong
authors.initials: Z
authors.lastname: Liu
authors.forename: Jiaqing
authors.initials: J
authors.lastname: Li
authors.forename: Shaofen
authors.initials: S
authors.lastname: Lin
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis; D002455:Cell Division / Q000187:drug effects; D004195:Disease Models, Animal; D007641:Keratolytic Agents / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000473:pathology; D017948:Retinal Rod Photoreceptor Cells / Q000187:drug effects* / Q000473:pathology; D017299:Rod Opsins / Q000032:analysis*; D014212:Tretinoin / Q000494:pharmacology*
chemical_list: D015415:Biomarkers; D007641:Keratolytic Agents; D017299:Rod Opsins; D014212:Tretinoin