Increased hyaluronan synthase-2 mRNA expression and hyaluronan accumulation with choroidal thickening: response during recovery from induced myopia

Invest Ophthalmol Vis Sci. 2010 Dec;51(12):6172-9. doi: 10.1167/iovs.10-5522. Epub 2010 Jun 23.

Abstract

Purpose: Several studies have convincingly shown that in chicks, compensation for imposed focus involves immediate changes in choroid thickness. The molecular events associated with choroidal thickening and the regulation of the choroidal response are largely unknown.

Methods: Form-deprivation myopia was induced in the right eyes of 2-day-old chicks by the application of translucent occluders for 10 days and was followed by unrestricted vision for an additional 1 to 20 days (recovery). Individual choroids were isolated from treated and control eyes and used for reverse transcription-quantitative PCR, hyaluronan (HA) localization with biotinylated hyaluronic acid binding protein (b-HABP), and analyses of HA size and concentration by size exclusion chromatography-multiangle laser light scattering (SEC-MALLS).

Results: HAS2 gene expression increased significantly after 6 hours of unrestricted vision (>7-fold) and peaked at 24 hours (>9-fold). In untreated eyes, HA was localized to perivascular sheaths of larger choroidal blood vessels; however, after 4 to 15 days of recovery, intense labeling for HA was detected throughout the thickened choroidal stroma. Analyses of choroidal HA by SEC-MALLS indicated that HA concentration was significantly increased in recovering choroids compared with controls after 4 to 8 days of recovery (≈3.5-fold).

Conclusions: Newly synthesized HA accumulates in the choroidal stroma of recovering eyes and is most likely responsible for the stromal swelling observed during recovery from myopia. This HA accumulation is initiated by a rapid increase in choroidal expression of the HAS2 gene in response to myopic defocus.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Newborn
  • Chickens
  • Choroid / metabolism*
  • Choroid / pathology*
  • Chromatography, Gel
  • Disease Models, Animal
  • Gene Expression Regulation, Enzymologic / physiology*
  • Glucuronosyltransferase / genetics*
  • Hyaluronic Acid / biosynthesis*
  • Hypertrophy
  • Male
  • Myopia / pathology*
  • RNA, Messenger / genetics*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Sensory Deprivation

Substances

  • RNA, Messenger
  • Hyaluronic Acid
  • Glucuronosyltransferase