title: Change in the synthesis rates of ocular retinoic acid and scleral glycosaminoglycan during experimentally altered eye growth in marmosets.
abstract: OBJECTIVE
  The purpose of this study was to examine the possibility that all-trans-retinoic acid (RA) in the eye is a signal related to changes in scleral extracellular matrix in a primate model of postnatal eye growth.
  
  
  METHODS
  Juvenile marmosets (Callithrix jacchus) were divided into two experimental groups based on their response to monocular deprivation with diffusers: group 1, treated eyes becoming longer than fellow control eyes (n = 8), and group 2, treated eyes becoming shorter than control eyes (n = 7). Eyes were enucleated, dissected, and assayed for changes in the rates of scleral glycosaminoglycan (GAG) synthesis and ocular RA synthesis. The rate of incorporation of (35)SO4 into CPC-precipitable GAG in scleras was taken as a measure of the rate of synthesis of proteoglycans. In the same eyes the rate of RA synthesis in vivo was measured separately in the retina and the choroid/RPE (choroid with RPE attached) by HPLC. The effect of RA on the rate of scleral GAG synthesis was also examined in tissue-cultured pieces of sclera from additional marmosets.
  
  
  RESULTS
  Induced changes in vitreous chamber length in diffuser-treated eyes correlated inversely with the rate of scleral GAG synthesis (P < 0.05) and directly correlated with the rate of RA synthesis measured separately in the retina (P < 0.05) and the choroid/RPE (P < 0.05). In group 1, the rate of scleral GAG synthesis was significantly lower (P < 0.01) in the treated eyes relative to control eyes, and the rate of RA synthesis in both the retina and the choroid/RPE was significantly higher (P < 0.01). In group 2, the rates of scleral GAG synthesis and RA synthesis in either the retina or choroid/RPE were not found to change significantly in the treated eyes compared with the control eyes. RA partially reduces the rate of scleral GAG synthesis in tissue-cultured primate sclera in a dose-dependent manner after several days.
  
  
  CONCLUSIONS
  RA may play a role in the visual control of postnatal eye growth in primates, possibly by inducing changes in scleral extracellular matrix associated with increasing eye size. Decreasing growth rate below control levels may involve other mechanisms.
authors.affiliation: Department of Biomedical Science and Disease, The New England College of Optometry, Boston, Massachusetts 02115, USA. troilod@neco.edu
authors.forename: David
authors.initials: D
authors.lastname: Troilo
authors.forename: Debora L
authors.initials: DL
authors.lastname: Nickla
authors.forename: James R
authors.initials: JR
authors.lastname: Mertz
authors.forename: Jody A
authors.initials: JA
authors.lastname: Summers Rada
mesh_terms: D000818:Animals; D002144:Callithrix; D002829:Choroid / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004247:DNA / Q000096:biosynthesis; D004195:Disease Models, Animal; D005109:Extracellular Matrix / Q000378:metabolism; D005123:Eye / Q000254:growth & development / Q000378:metabolism; D006025:Glycosaminoglycans / Q000096:biosynthesis*; D009216:Myopia / Q000378:metabolism*; D009924:Organ Culture Techniques; D012160:Retina / Q000378:metabolism*; D012590:Sclera / Q000187:drug effects / Q000378:metabolism*; D012683:Sensory Deprivation; D014212:Tretinoin / Q000378:metabolism* / Q000494:pharmacology; D014822:Vitreous Body / Q000254:growth & development / Q000378:metabolism
chemical_list: D006025:Glycosaminoglycans; D014212:Tretinoin; D004247:DNA