RESUMO
BACKGROUND:Taurine is an important non-enzymatic system antioxidant in the lens.The mechanism of its anti-oxidative effect is mainly to protect lens from oxidative injury by anti-lipid peroxidation.OBJECTIVE:This study was to observe the effect of exogenous taurine on lens epithefial cell apoptosis-induced by H2O2 in vitro.DESIGN:A randomized controlled animal experiment.SETTING:Department of Ophthalmology,Affiliated Hospital of Qingdao University Medical College.MATERIALS:Seventy-five adult New Zealand standard tabbits,of either gender,weighing 1.5-2.5 kg,were provided by Qingdao Laboratory Animal Center.Reagent kit for in situ detecting cell apoptosis(Sigma Company,USA),taurine and H2O2(Shanghai Guangda Chemical Reagent Factory,China)were included in this study.METHODS:This study was performed in the Department of Ophthalmology and Central Laboratory.Affiliated Hospital of Qingdao University Medical College from Mav 2005 to June 2007.Rabbit lenses were harvested and randomly divided into 3 groups:control group,in which,clear lenses were incubated in non-serum and non-phenolsulfonphthalein MEM medium which was renewed every 24 hours,H2O2 group,in which,clear lenses were incubated in non-serum and non-phenolsulfonphthalein MEM medium containing 1 mmol/L H2O2 with addition of 62 μL H202(30 g/L)every 6 hours,and H2O2+taurine group,in which,clear lenses were incubated in non-serum and non-phenolsulfonphthalein MEM medium containing 1 mmol/L H2O2 and 10 g/L taurine.which was renewed every 6 hours.The protocol was conducted in accordance with ethical guidelines for the use and care of animals.MAIN OUTCOME MEASURES:Observation of lens opacity 6.12,24.48 and 72 hours after culture;Lens epithelial cell apoptosis determined by DNA in situ end labeling and DNA fragment analysis.RESULTS:Lens opacity:The lens opacity in the H2O2 group was aggregrated gradually along with the time of oxidative injury.The lens opacity in the H2O2 group was severer than that in the H2O2+taurine group.Lens epithelial cell apoptosis:There were no apoptotic cells in the control group within 72 hours.The number of apoptotic cells in the H2O2 group was increased gradually with the prolonged time of oxidative injury.Till the 72nd hour,the cells were all tamed into apoptotic cells.A few aopototic celIs were found in the H2O2+taurine group since hour 24,and then were more and more,and the number of apoptotic cells accounted for about 30%at hour 72.The apoptotic rate in the H202+taurine group was significantly lower than that in the H2O group at each time point(q=8.6845,P＜0.01).There was no significant difference in apoptotic rate between the H202+taurine group and the control group (P＞0.05). Findings of DNA fragmentation assay:The DNA"ladder"was found in the H2O2 group at hours 24,36,48 and 72,while no DNA"ladder"but only normal electrophoresis straps were present in the other two groups 24 hours after culture.CONCLUSION:Taurine can inhibit the oxidative injury-induced apoptosis of rabbit lens epithelial cells,and alleviate lens opacity.
RESUMO
BACKGROUND: Oxidation injury can lead to the apoptosis of lens epithelial cells. Some researches have found that body supplement of vitamin C is beneficial to inhibit oxidation injury by increasing the level of vitamin C in aqueous humor.OBJECTIVE: To observe the inhibitive effect of vitamin C on H2O2 induced apoptosis of lens epithelial cell.DESIGN: Randomized controlled trial taking animal's lens as subject.SETTING: Department of Ophthalmology, Medical College of Qingdao University.MATERIALS: 120 adult New Zealand rabbits of both genders, weighing 3-5 kg, were selected. Vitamin C and 300 g/L H2O2 were purchased from Shanghai Guangda Chemical Reagent Factory.METHODS: The experiment was carried out in the Central Laboratory, the Affiliated Hospital of Medical College of Qingdao University from January 2002 to January 2004. ①Culture of lens: 240 lenses were isolat ed from 120 rabbits after being killed. Among them, 192 clear lenses were selected and divided randomly to three groups with 64 lenses in each group: control group, H2O2 group and H2O2+vitamin C group. Lenses in the control group were incubated in non-serum and non- phenolsulfonphthalein MEM medium, those in the H2O2 group incubated in non serum and non- phenolsulfonphthalein MEM medium containing 1 mmol/L H2O2 (62 μL of 30 g/L H2O2 was added into the medium every 6 hours to keep H2O2 level maintain 1 mmol/L in the medium), and those in the H2O2+vitamin C group incubated in non-serum and non- phenolsulfonphthalein MEM medium containing 1 mmol/L H2O2 and 1 mmol/L vitamin C. Under the same culture condition, the lenses in each group were detected at hours 6, 12, 18, 24, 36, 48, 72 and 108 after culture, respectively. ②Measurement of the opacity of lens: Under the white background, two black lines 0.5 mm in width, which were mutually vertical with an interval of 10 mm. The lenses were placed above the crossing to measure the opacity. ③Detecting the apoptosis of lens epithelial cells:The apoptosis of lens epithelial cells was examined using TUNEL method and DNA fragmentation assay under light microscope to calculate the apoptotic rate of epithelial cells.MAIN OUTCOME MEASURES: ①Opacity of the lenses in each group;②apoptotic rate of lens epithelial cells in each group.RESULTS: ①After 108 hours of culture, the opacity of the lenses in the H2O2+vitamin C group was obviously lower than that in the H2O2 group. ②The apoptotic rates in the control group were lower that those in the H2O2group at different time point and those in the H2O2+vitamin C groupat hours 24, 48 and 72 after culture(P＜0.05-0.01). The apoptotic rates in the H2O2+vitamin C group were significantly lower than those in the H2O2group at different time points after culture (P＜0.01). ③The findings of DNA fragment analysis showed that the DNA "ladder" was found in the H2O2 group during 24-72 hours, while no DNA "ladder" but only normal electrophoresis strap were present in the other two groups 24 hours after culture.CONCLUSION: Lens can take refuge from the oxidative injury of H2O2with the addition of vitamin C. As a result, the apoptosis rate of lens epithelial cells and further, cataract formation can be restrained.