Protective effects of vitamin e on uvb irradiation in guinea pigs: importance of free radicals

In this study, it is aimed to experimentally investigate how much the topical application of vitamin E acetate, an antioxidant agent, changes the deterioration of antioxidant capacity due to ultraviolet B (UVB) radiation, before and after single dose UVB radiation. 56 albino guinea pigs were taken to the study. Back area of the anesthetized guinea pigs were shaved with an average of 35 cm2 The guinea pigs were divided into four groups. Nothing was applied to the control group after shaving. One group of guinea pigs were only given UVB. One dose of vitamin E acetate was administered topically to another group immediately after they were given UVB. Vitamin E acetate was applied topically to another group for 3 weeks, and after the last application of vitamin E, UVB was given. Excluding the control group, half of the guinea pigs in the groups were killed by decapitation 24 hours after the UVB exposure, and the other half were killed by decapitation 48 hours after the UVB exposure. All of the decapitated guinea pigs were studied for lipid peroxide in skin, liver, plasma and erythrocytes; for superoxide dismutase in haemoglobin and skin; for glutathione peroxidase in skin and erythrocytes, and for reduced glutathione in erythrocytes. In both groups with topically applied vitamin E, the skin and liver peroxide values were significantly suppressed compared to the increased levels of the group with only the UVB applied. In both groups with topically applied vitamin E, the erythrocyte lipid peroxide levels were comparable with the levels of the group with only the UVB applied. The increase of the plasma lipid peroxide levels measured at the 48th hour after the application of the UVB compared to the control groups were higher in the groups that are treated with vitamin E acetate compared to the group treated with only the UVB. It was noted that the decrease in skin GSHPx level at 24th hour compared to the group treated with UVB only showed a less increase at 48th hour in both groups treated with vitamin E, however, these were not statistically significant. Decreases of erythrocyte GSHPx values at 48th hour were statistically not significant in the single dose E vitamin group compared to the only UVB treated group and a statistically significant decrease was observed in the 3 weeks E Vitamin treated group compared to the only UVB treated group. In all the groups, the skin GSHPx levels were decreased compared to the control group. These levels were higher at the 48th hour after the UVB application compared to the levels at the 24th hour. The difference between the levels at the 48th hour and at the 24th hour was less in the groups treated with vitamin E acetate; in fact, this difference was statistically insignificant in the groups treated with vitamin E acetate. In all three groups the erythrocyte GSHPx levels at the 48th hour after the UVB application were decreased compared to the control group. The difference between the GSHPx levels of the group with only the UVB treatment and the group treated with single dose vitamin E acetate was statistically insignificant. The difference between the GSHPx levels of the group with only the UVB treatment and the group treated with vitamin E acetate for three weeks was statistically significant. In the study, erythrocyte GSH values of the group with only UVB treated and both groups with vitamin E acetate were found to be increased statistically significantly compared to the control group. The differences between the groups, excluding the control group, were statistically insignificant. The group treated with single dose of vitamin E acetate demonstrated better recovery from the decreased skin and haemoglobin SOD values resulted from the UVB application, compared to the group treated with 3 weeks of vitamin E. It is concluded that the application of the single dose of vitamin E acetate after the UVB radiation and the administration of vitamin E acetate 3 weeks before the UVB radiation were effective against the harmful effects of the UVB radiation.