| Sulfur dioxide(SO2) is an important air pollutant all over the world, which exists as low concentrations in the atmosphere and high concentrations in some industrial areas.High doses of SO2 exposure make city environment deteriorated and have severely threatened human health.Many studies of epidemiology show that SO2 can not only cause respiratory tract diseases,but also affect cardiovascular system and genital system.Toxicology evidences also indicate that SO2 may cause toxicological damage to multiple organs of animals,and some of them are even severer than damages in lungs.Recently few data are available on the effects of exposed to the pollutant on the molecular mechanism,although some biochemical changes,genetic toxicity, oxidative stress and DNA damage have been detected.In order to explore the role of SO2 on protein oxidative damage in mice and its molecular mechanism,the effects of protein and DNA damage of SO2 in different organs and tissues were studied.It will provide based data for the protein oxidative damage,nucleic acid damage,the occurrence of diseases, development,the prevention,control and clinical diagnosis.The mice were treated with SO2 at different concentrations(0,14,28 and 56 mg/m3) for 6 hours per day for 7 days.The protein carbonyl(PCO) content was measured by using spectrophotometric DNPH assay,and the DNA-protein crosslinks (DPC) coefficient was measured by using KCl-SDS assay.It will be used to estimate the degree of oxidative damage of protein and nucleic acid induced by SO2.1.Effects of sulfur dioxide on protein carbonyl(PCO) content in different tissues of mice When the concentration of SO2 was 14 mg/m3,it could induce the increase of PCO levels in hearts,livers,lungs,brains,spleens,kidneys and stomachs of female and male mice.Compared with the control,PCO contents in livers and lungs of female mice have highly significant and very significant increase(P＜0.01 and P＜0.001),while PCO contents in livers, lungs and spleens of male mice have very significant increase(P＜0.001), PCO contents in kidneys and stomachs have significant increase(P＜0.05). When the concentrations of SO2 were 28 mg/m3 and 56 mg/m3,PCO contents in seven tissues of female and male mice have significant increase(female: stomach P＜0.05,heart,brain and spleen P＜0.01,liver,lung and kidney P＜0.001 male:stomach P＜0.05,brain and kidney P＜0.01,heart,liver,lung and spleen P＜0.001).As the concentration of SO2 increases,PCO contents continue to increase(female:stomach P＜0.05,heart,liver,lung,brain,spleen and kidney P＜0.001 male:kidney and stomach P＜0.01,heart,liver,lung, brain and spleen P＜0.001).Through the comparison of male and female mice, it could be concluded that the PCO levels of heart and liver have differences between female and male mice at the concentration of 56 mg/m3(P＜0.05).It showed that protein oxidative damage to the female mice is more serious.2.Effects of sulfur dioxide on DNA-protein crosslinks(DPC) content in different histiocytes of miceWhen the concentration of SO2 was 14 mg/m3,it could induce the increase of DPC%levels in hearts,livers,lungs,brains,spleens,kidneys and stomachs of female and male mice.Compared with the control,DPC% contents in lungs and kidneys of female mice have significant and highly significant increase(P＜0.05 and P＜0.01),while DPC%contents in spleens and kidneys of male mice have significant increase(P＜0.05).When the concentrations of SO2 were 28 mg/m3 and 56 mg/m3,DPC%contents in seven histiocytes of female and male mice have significant increase(female: brain and stomach P＜0.05,kidney P＜0.01,lung and spleen P＜0.001 male: heart,liver and stomach P＜0.05,lung and spleen P＜0.01,kidney P＜0.001). As the concentration of SO2 increases,DPC%contents continue to increase (female:brain P＜0.05,heart,liver,lung,spleen and kidney P＜0.001 male: stomach P＜0.05,heart,liver,lung,spleen and kidney P＜0.001).Through the comparison of male and female mice,it ccould be concluded that DPC% contents of lungs,brains and stomachs have differences between female and male mice at the concentration of 56 mg/m3(P＜0.05).The damage to the female mice is more serious.When the concentrations of SO2 were 28 and 56 mg/m3,DPC%levels had also differences in spleens(P＜0.01).But DPC% contents in the other histiocytes had no differences between female and male mice.3.ConclusionIn all,SO2 exposure could cause the formation of PCO and DNA-protein crosslinks(DPC) in hearts,livers,spleens,lungs and kidneys of mice compared with the control at the concentration of 14 - 56 mg/m3.The increases of PCO and DPC contents share the same regulation in a concentration(SO2)-dependent manner.The concentration-response linear equations and the related correlation coefficients are higher than 0.9.Its toxicological mechanism may be that when SO2 was inhaled into the body,it could induce the body to produce.OH and O2-.or inhibite the activity of the body antioxidase.At last it would cause the accumulation of excessive free radical,even damaged protein and DNA of the body.Through the comparison of male and female mice,it can be concluded that the PCO levels of hearts and livers and the DPC%levels of lungs,brains and stomachs have differences between female and male mice at the concentration of 56 mg/m3 (P＜0.05);when the concentrations of SO2 were 28 and 56 mg/m3,DPC% levels have also differences in spleen(P＜0.01).Generally speaking,protein oxidative damage and DPC%levels to the female mice are more serious.The results support the topic that SO2 is a systemic toxicant.
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