RESUMO
Objective To study the effect of lipid peroxidation and anti-lipid peroxidation and the pigment in skin of C57BL/6 mice exposed to arsenic.Methods Forty male C57BL/6 mice were divided into four groups via the random number table method,ten mice in each group,and the mice were fed ad libitum drinking water containing arsenic at 0,1,5 and 25 mg/L concentrations for a period of 6 weeks,respectively.Twelve days before the end of the experiment,procedure of depilation was performed to induce anagen of hair cycle.On the 30th day of experiment,the activity of superoxide dismutase (SOD) was determined by nitrite method,the activity of glutathione peroxidase (GSH-Px) was determined by dithiobisobenzoic acid method,the content of malondialdehyde (MDA) in skin of C57BL/6 mice was determined by thiobarbituric acid method.Melanin was measured by NaOH dissolution method.Results No significant difference was found in body weight and water intaken between groups (F =0.119,0.363,P ＞ 0.05).The activity of SOD [(16.00 ± 5.05),(13.96 ± 2.02),(10.46 ± 3.14) U/mg prot] in 1,5 and 25 mg/L arsenic groups were all significantly lower than that in control group [(20.36 ± 4.82) U/mg prot,P ＜ 0.05].GSH-Px activity in 1,5 and 25 mg/L arsenic groups [(98.14 ± 23.92),(87.18 ± 10.87),(53.56 ± 19.97) U/mg prot] were all significantly lower than that in control group [(119.34 ± 33.14) U/mg prot,P ＜ 0.05].While MDA levels in 5 and 25 mg/L arsenic groups [(9.09 ± 2.04),(11.48 ± 2.21) nmol/mg prot] were significantly higher than that of control group [(6.19 ± 0.56) nmol/mg prot,P ＜ 0.05] and that of 1 mg/L arsenic group [(6.52 ± 1.67) nmol/mg prot,P ＜ 0.05).No significant difference was found in melanin levels (P ＞ 0.05).Conclusions Lipid peroxidation and the decreasing of antioxidation may be one of the mechanisms of arsenic-induced skin damage.Arsenic-induced skin melanin content change is not found.
RESUMO
Objective To study the efficacy of L-3,5-diiodotyrosine (DIT) and inorganic iodine (KIO3) in iodine-deficiency Wistar rats.Methods Sixty Wistar rats,weighting about 160-180 g,were divided into two groups according to body weight by the random number table method:iodine-deficiency model (40 rats) was fed with low-iodine food (the iodine content was 35.9 μg/kg);optimal-iodine model (20 rats) was fed with low-iodine food and given with KIO3 water (the iodine content was 18 mg/L) 0.5 ml by intragastric once a day.Model was established for 3 months.Iodine-deficiency model was subdivided into low iodine (LI) group,KIO3 group and DIT group,eight,nine,ten rats in each group;from optimal-iodine model,nine rats were randomly selected as optimal iodine (NI) group.LI group was fed with low-iodine food;KIO3 group was fed with low-iodine food and given with KIO3 water (the iodine content was 18 mg/L) 0.5 ml by intragastric once a day;DIT group was fed with low-iodine food and given with DIT water (the iodine content was 18 mg/L) 0.5 ml by intragastric once a day;NI group was fed with low-iodine food and given with KIO3 water (the iodine content was 18 mg/L) 0.5 ml by intragastric once a day.After 3 months,24-hour urine of the rats was collected.According to the method for determination of iodine in urine by As3 +-Ce4+ catalytic spectrophotometry (WS/T 107-2006),iodine content in urine was detected.Rats were anesthetized intraperitoneally with 25％ urethane,blood from abdominal aortic was collected to determinate the serum thyroid hormone [total triiodothyronine (TT3),total thyroxine (TT4),free triiodothyronine (FT3),free thyroxine (FT4)] level in rats by automatic electrochemical luminescence immunoassay.All the rats were sacrificed to analyze the thyroid weight.Results ① The urine iodine showed significant differences in the four groups (x2 =25.24,P ＜ 0.05).The median of urine iodine concentration in the LI,NI,KIO3 and DIT groups were 3.00,286.14,223.37,214.33 μg/L,respectively.The urine iodine concentration in LI group was significantly lower than those of other three groups (all P ＜ 0.05).② The serum TT3,TT4,FT3,FT4 levels showed significant differences in the four groups (F =63.48,140.73,130.20,365.27,all P ＜ 0.05).And the hormone levels in KIO3 group were lower than those of the DIT group [TT3:(1.57 ± 0.20) vs.(1.97 ± 0.18) mmol/L,TT4:(51.23 ± 4.90) vs.(71.94 ± 5.27) mmol/L,FT3:(5.34 ± 0.45) vs.(6.98 ± 0.33) pmol/L,FT4:(26.18 ± 2.30) vs.(35.47 ± 2.28) pmol/L,all P ＜ 0.05].③The color of thyroid in KIO3 and DIT groups became pale pink.The absolute and relative thyroid weight showed significant differences in the four groups (F =225.05,345.40,all P ＜ 0.05).The absolute thyroid weight [(31.76 ± 1.75) mg] and relative thyroid weight [(11.69 ± 3.47) mg/100 g] in DIT group was lower than that of the KIO3 group [(36.31 ± 5.23) mg,(12.83 ± 4.38) mg/100 g,all P ＜ 0.05].Conclusion Animal experimental results show that DIT has a better iodine-supplementing efficacy than that of KIO3.