title: L-carnitine protects human retinal pigment epithelial cells from oxidative damage.
abstract: OBJECTIVE
  To determine the efficacy of L-carnitine (LC) against oxidative changes in human retinal pigment epithelium (RPE) cells.
  
  
  METHODS
  The RPE cells from human donor eyes were cultured in Hams F-10 medium. The effect of LC on H2O2-induced morphologic changes in the RPE cells was analyzed by light microscopy. Reduction in cell death after the impact of LC treatment on H2O2-treated cells was analyzed by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assays. In addition, the effect of H2O2 on the activity of RPE-antioxidant enzymes, glutathione (GSH) and superoxide dismutase (SOD), and LC-induced protection was also determined.
  
  
  RESULTS
  LC protected the RPE cells by inhibiting the peroxide-induced cytopathic effect from 50% to 10%. Nuclear condensation observed in 40% of the H2O2-treated cells decreased to 20% after LC treatment. The MTT assays demonstrated that 100 microM oxidant caused appreciable cell death, which was reduced by LC treatment; however, 100% protection was not achieved. Significant peroxide-induced cell death was seen within 5 hr of H2O2 treatment, and a quantifiable reduction was observed after LC treatment for a similar time period. The change in the antioxidant potential of the RPE induced by oxidative stress was restored by LC treatment, as demonstrated by an increase in GSH and SOD activities.
  
  
  CONCLUSIONS
  LC is capable of protecting the RPE cells from H2O2-induced oxidative damage, implying that micronutrients can have a positive effect and can play an important role in the treatment of oxidation-induced ocular disorders. Further studies are needed to understand the mechanism of LC-induced protection to the RPE cells.
authors.affiliation: Research Department, King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia. dr_farrukhshamsi@yahoo.com
authors.forename: Farrukh A
authors.initials: FA
authors.lastname: Shamsi
authors.forename: Imtiaz A
authors.initials: IA
authors.lastname: Chaudhry
authors.forename: Mike E
authors.initials: ME
authors.lastname: Boulton
authors.forename: Ali A
authors.initials: AA
authors.lastname: Al-Rajhi
mesh_terms: D000328:Adult; D002331:Carnitine / Q000494:pharmacology*; D002470:Cell Survival; D002478:Cells, Cultured; D019610:Cytoprotection / Q000187:drug effects; D005562:Formazans; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000633:toxicity*; D008875:Middle Aged; D016877:Oxidants / Q000633:toxicity*; D018384:Oxidative Stress; D010857:Pigment Epithelium of Eye / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D013482:Superoxide Dismutase / Q000378:metabolism; D013778:Tetrazolium Salts; D014803:Vitamin B Complex / Q000494:pharmacology*
chemical_list: D005562:Formazans; D016877:Oxidants; D013778:Tetrazolium Salts; D014803:Vitamin B Complex; C079782:MTT formazan; D006861:Hydrogen Peroxide; D013482:Superoxide Dismutase; D005978:Glutathione; D002331:Carnitine