title: Infrared irradiation alters the expression of matrix metalloproteinases and glycosaminoglycans in the cornea and crystalline lens.
abstract: BACKGROUND
  Prolonged exposure to infrared (IR) radiation is associated with different types of damage to cornea and lens. The aim of our study was to investigate the effect of acute and chronic exposure to IR radiation on the activity of matrix metalloproteinase-2 (MMP-2) and MMP-9 and on the expression of glycosaminoglycans (GAG) in the rabbit cornea and crystalline lens.
  
  
  METHODS
  New Zealand rabbits were subjected to IR radiation for 4 months (chronic exposure to IR) or to normal light (control group). In experiments regarding acute exposure, animals were subjected to IR radiation or normal light for 12 h, in the presence of 0.1% diclofenac sodium (eye drops instilled in the right eye of animals) or saline (instilled in the left eye of animals). The cornea and lens were dissected away and homogenized. The activity of MMP-2 and MMP-9 was assayed by gelatine zymography. Total GAG were isolated from tissue specimens after lipid extraction and extensive digestion with pronase and DNase and characterized by treatment with GAG-degrading enzymes, followed by electrophoresis on cellulose acetate membranes.
  
  
  RESULTS
  Acute or chronic exposure to IR radiation induced the activity of MMP-2 in cornea and lens, whereas only acute IR radiation increased the content of heparan sulphate in crystalline lens. Local administration of diclofenac sodium did not prevent the above effects of acute IR radiation.
  
  
  CONCLUSIONS
  The detrimental effects of excessive or prolonged exposure of the eyes to IR radiation are associated with induced activity of MMP-2 in cornea and lens and alterations in the content of heparan sulphate in lens. Thus, MMP and GAG may offer alternative targets for pharmacological intervention to confront ocular damages associated with IR radiation.
authors.affiliation: Laboratory of Experimental Ophthalmology, Aristotle University of Thessaloniki, Thessaloniki, Greece.
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Dadoukis
authors.forename: Ioannis
authors.initials: I
authors.lastname: Klagas
authors.forename: Anastasia
authors.initials: A
authors.lastname: Komnenou
authors.forename: George
authors.initials: G
authors.lastname: Karakiulakis
authors.forename: Athanasios
authors.initials: A
authors.lastname: Karoutis
authors.forename: Vassilios
authors.initials: V
authors.lastname: Karampatakis
authors.forename: Eleni
authors.initials: E
authors.lastname: Papakonstantinou
mesh_terms: D000208:Acute Disease; D000818:Animals; D002908:Chronic Disease; D003315:Cornea / Q000187:drug effects / Q000201:enzymology / Q000528:radiation effects*; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004008:Diclofenac / Q000494:pharmacology; D004586:Electrophoresis; D004588:Electrophoresis, Cellulose Acetate; D006025:Glycosaminoglycans / Q000378:metabolism*; D006801:Humans; D007259:Infrared Rays; D007908:Lens, Crystalline / Q000187:drug effects / Q000201:enzymology / Q000528:radiation effects*; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D011817:Rabbits; D011833:Radiation Injuries, Experimental / Q000201:enzymology*
chemical_list: D016861:Cyclooxygenase Inhibitors; D006025:Glycosaminoglycans; D004008:Diclofenac; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9