title: The effect of single and repeated UVB radiation on rabbit cornea.
abstract: BACKGROUND
  Cumulative effect of ultraviolet radiation (UVR) is an important aspect of UV corneal damage. The purpose of this study was to apply high resolution magic angle spinning proton nuclear magnetic resonance (HR-MAS 1H NMR) spectroscopy to evaluate the effect of single and repeated UV radiation exposure of the same overall dose on the rabbit cornea.
  
  
  METHODS
  Corneal surfaces of 24 normal rabbit eyes were examined for the effects of UVB exposure (312 nm). In the first group (UVB1), animals were irradiated with a single dose (3.12 J/cm2; 21 min) of UVB radiation. The animals in the second group (UVB2) were irradiated three times for 7 min every other day (dose of 1.04 J/cm2; days 1, 3, 5) to give the same overall dose (3.12 J/cm2). The third group served as an untreated control group. One day after the last irradiation, the animals were sacrificed, and the corneas were removed and frozen. HR-MAS 1H NMR spectra from intact corneas were obtained. Special grouping patterns among the tissue samples and the relative percentage changes in particular metabolite concentrations were evaluated using modern statistical methods (multivariate analysis, one-way ANOVA).
  
  
  RESULTS
  The metabolic profile of both groups of UVB-irradiated samples was significantly different from the control corneas. Substantial decreases in taurine, hypo-taurine and choline-derivatives concentrations and substantial elevation in glucose and betaine levels were observed following the UVR exposure. There was no significant difference between the effect of a single and repeated UVB irradiation of the same overall dose.
  
  
  CONCLUSIONS
  For the first time, the effects of single and repeated UVR doses on the metabolic profile of the rabbit cornea were analysed and compared. The combination of HR-MAS 1H NMR spectroscopy and modern statistical methods (multivariate analysis, one-way ANOVA) proved suitable to assess the overall view of the metabolic alterations in the rabbit corneal tissue following UVB radiation exposure.
authors.affiliation: Department of Neuroscience, Faculty of Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway. miroslav.fris@ntnu.no
authors.forename: Miroslav
authors.initials: M
authors.lastname: Fris
authors.forename: May-Britt
authors.initials: MB
authors.lastname: Tessem
authors.forename: Jitka
authors.initials: J
authors.lastname: Cejková
authors.forename: Anna
authors.initials: A
authors.lastname: Midelfart
mesh_terms: D000818:Animals; D003315:Cornea / Q000528:radiation effects*; D019906:Nuclear Magnetic Resonance, Biomolecular; D011817:Rabbits; D011829:Radiation Dosage; D011833:Radiation Injuries, Experimental / Q000209:etiology* / Q000378:metabolism; D014466:Ultraviolet Rays / Q000009:adverse effects*