The effect of fractions extracted from green tea and catechins on lipid peroxidation induced by rose bengal and blue light exposure were investigated using porcine retinal homogenate. Thiobarbituric acid reactive substances (TBARS) were measured as lipid peroxide and expressed as nmol malondialdehyde (MDA) per milligram protein. In the presence of 10μM rose bengal and after 30-minute exposure to blue light, the levels of TBARS in 5 % porcine retinal homogenates was 72.1±5.7 nmol MDA/mg protein. Addition of fractions (25μg/mL) extracted from green tea significantly decreased the production of TBARS to 32.2±2.7 nmol MDA/mg protein. The inhibitory rates were directly proportional to the concentrations of epicatechin gallate (ECG) and epigallocatechin gallate (EGCG) in the fraction extracted from green tea, but were not proportional to the concentrations of (+) - catechin, epicatechin (EC) or caffeine. The 50 % inhibitory concentration (ICso) of the purified ECG, EGCG, EC and (+) - catechin were 3.8, 5.3, 39.0 and 98μM, respectively. These results confirm that ECG and EGCG extracted from green tea are mainly responsible for the inhibition of the lipid peroxidation in this system.
The purpose of this study was to establish an only–ankle–immobilization model. We divided 10 Wistar male rats into a control group (Cont, n=5) and immobilization group (IM, n=5). IM had their right ankle immobilized in planter flexion (PF) using external fixation for 4 weeks, while Cont were observed without immobilization for 4 weeks. All rats gained weight during the 4 weeks without significant differences between groups. Range of motion (ROM), pain threshold, and body weight were measured in all rats once a week for the 4 weeks. ROM of ankle dorsiflexion (DF) and PF, knee extension, and flexion were measured using X–ray fluoroscopy with a tension gauge, and pain thresholds were evaluated by behavioral response with the von Frey test and Hargreaves Assay using a plantar test. All data were shown as % of right limb ⁄ left limb. Ankle DF in IM was significantly limited 1 week after immobilization (83.7% vs. Cont: 98%, p<0.05), and it continued decrease to 70.4%, 51.5%, and 61.9% after 2, 3, and 4 weeks, respectively (vs. Cont: 99.4%, p<0.01). Ankle PF, knee extension, and flexion showed no significant difference between the groups. In the von Frey test, the mechanical hyperalgesia threshold in IM was significantly decreased to 45.8% after 1 week compared to the Cont rats (90.4%, p<0.01), and then further to 21.4%, 17.7%, and 20% after 2, 3, and 4 weeks, respectively (vs. Cont, p<0.01). In the plantar test, thermal nociceptive thresholds significantly decreased to 62.9% after 1 week in IM (vs. Cont: 96.7%, p<0.01), and then further to 83.3%, 70.6%, and 76% after 2, 3, and 4 weeks, respectively (vs. Cont, p<0.01). The model shown here will be useful for further studies to investigate the mechanisms and treatments of immobilization.
The aim of this study was to investigate the effect of A-3922, a dihydrobenzofuran derivative, on hydroperoxide (H2O2) -induced PC12 cell injury. H2O2-induced PC12 cell injury was determined by lactate dehydrogenase (LDH) release. The concentration of lipid peroxide was determined from the amount of thiobarbituric acid reactive substances (TBARS) in PC12 cell homogenate. Following exposure to 150 μM H2O2 for 45 min (Condition I), the LDH activity increased to 181 ± 6 % of control activity (n = 11, P < 0.01) . The LDH activity significantly decreased to 128 ± 6 % (n = 15, P < 0.01 vs Condition I) when PC12 cells were exposed to 150 μM H2O2 combined with 10 μM A-3922 (Condition II), and 161 ± 7 % (n = 15, P < 0.01 vs Condition I) when pre-treated with 10 μM A-3922 prior to the addition of 150 μM H2O2 (Condition III) . Lipid peroxidation of PC12 cells induced by 25 mM 2, 2'-azobis (2, 4-dimethyl-valeronitrile), a lipophilic radical initiator, was inhibited by the addition of 100 μM A-3922. These results indicate that A-3922 exerts a protective effect against oxidative stress-induced PC12 cell injury, in part through the inhibition of lipid peroxidation in the cell membrane.
The aim of this study was to determine ultraviolet (UV) action spectra for cell killing of primary porcine lens epithelial cells (LECs) that can be used to establish guidelines for evaluation of the hazard of cataract due to UV exposure in the workplace.Primary porcine LECs were exposed to different doses (radiant exposure) of UV at 17 different wavelengths from 235 nm to 311 nm. At 2 days after exposure, cell viability was assessed by measuring crystal violet staining of the cells and lactate dehydrogenase release into the culture medium. The exposure dose required to kill 50% of cells (LD(50)) was determined from the dose-effect relationship obtained at each wavelength and was used to construct action spectra.The action spectra had a broad minimum in the approximate range of 250-280 nm, indicating that UV is most hazardous to porcine LECs within this wavelength range. The spectra rose steeply at both longer and shorter wavelengths. These action spectra are consistent with the in vivo action spectra for opacities in the rabbit lens and for light scattering in the rat lens, taking the transmittance of the ocular media into account.These results will help to determine a UV hazard function for cataract formation, which can be used to draft guidelines for evaluation of the hazard of cataract due to UV exposure in the workplace.
It is possible that oxidative stress causes several retinal diseases. However, the natural biogenic role of antioxidants in the retina is not clear.This study investigates the change in concentration of vitamin E (VE), ascorbate and glutathione (GSH) in the retina following vitreous injection of 600 mug 18:2 linoleic acid hydroperoxide (LHP) in male New Zealand rabbits.LHP was injected above the retinal surface. The animals were sacrificed and the eyes enucleated before LHP injection, 1, 3, 6, 12, 24 h and 4 and 7 days after LHP injection. Retinas were removed, VE and ascorbate measured by HPLC, and GSH determined by a fluorometric method.The concentration of VE in the retina decreased from pretreatment levels of 154.6 +/- 29.7 nmol/g wet weight (n = 7) and was lowest at 6 h (61.1 +/- 18.1 nmol/g wet weight, n = 4, p < 0.05), then increased gradually, returning slowly to pre-LHP levels by 7 days. The concentration of ascorbate in control retinas decreased at 6 h from pretreatment levels of 7.33 +/- 0.93 micromol/g wet weight (n = 7) to 2.74 +/- 0.16 micromol/g wet weight (n = 4, p < 0.05) and returned to pretreatment levels rapidly by 24 h after injection. The concentration of GSH in retinas decreased from baseline levels of 109.53 +/- 8.19 microg/g wet weight (n = 9), was lowest at 12 h (72.40 +/- 11.17 microg/g wet weight, n = 5, p < 0.05) and returned to pretreatment levels by 7 days.The results suggest that intravitreous LHP injection is a contributor to oxidative stress in the rabbit retina by causing a reduction in antioxidant capacity.
