title: Retinoic acid metabolic change in retina and choroid of the guinea pig with lens-induced myopia.
abstract: OBJECTIVE
  To investigate the role of retinoic acid (RA) and retinaldehyde dehydrogenase-2 (RALDH(2)) of retina and choroid in the guinea pig lens-induced myopic eyes.
  
  
  METHODS
  Totally 45 guinea pigs, at age of three weeks, were randomly assigned into three groups: the normal control, the lens-induced group and the recovering group. Out of focus was induced by the -6.00D concave lens on the left eye, and lasted for 15 days. All animals underwent biometric measurement (corneal radius of curvature, refraction and axial length). Subsequently, RA content in the retina and RPE/choriod complex was detected by reversed-phase high-performance liquid chromatography. RALDH(2) protein in the retina and RPE/choriod complex was evaluated by the immunohistochemical staining and Western blotting.
  
  
  RESULTS
  After wearing -6.00D lens for 15 days, axial length of the lens-induced eye extends and myopia was formed, with RA contents increasing in both the neural retina and RPE/choroid complex. Comparing with the lens-induced group, myopic degree significantly relieved, and its RA contents in both the neural retina and RPE/choroid complex decreased in the recovering group. In the normal control, RALDH(2) protein was expressed positively in the retinal nerve fiber layer (RNFL), inner plexiform layer (IPL) and lateral border of outer nuclear layer (ONL). Retinal RALDH(2) protein increased in the lens-induced group, and was also positive in the outer plexiform layer (OPL). In the recovering group, retinal RALDH(2) protein attenuated the expression in the OPL turns to negative. RALDH(2) protein was not expressed in the choroid of any group.
  
  
  CONCLUSIONS
  RA of retina and chorid participates in the regulation of the lens-induced myopia in guinea pigs, which may be related with retinal RALDH(2) protein.
authors.affiliation: Department of Ophthalmology, Xiangya Hospital of Central South University, Changsha 410008, Hunan Province, China.
authors.forename: Jun-Feng
authors.initials: JF
authors.lastname: Mao
authors.forename: Shuang-Zhen
authors.initials: SZ
authors.lastname: Liu
authors.forename: Xiu-Qiong
authors.initials: XQ
authors.lastname: Dou
keywords: guinea pig; lens-induced myopia; retinaldehyde dehydrogenase-2; retinoic acid