Changes In Lipid Peroxidation And The Gene Expression Level Of GPx,SOD In Kidney Of Hypothyroid Rats

Objective:1 The research observed the histology level of GSH-PX (glutathione peroxidase),SOD(superoxide dismutase) and the major medium production of lipid peroxidation MDA (malondialdehyde) and activity of Na+,K+-ATPase,Ca2+-ATPase in kidney of hypothyroid rats.2 To observe the gene expression level of GSH-PH,SOD in kidney of hypothyroid rats.Methods:At the base of the animal models of hypothyroid, We have observed the capability of kidney antioxidation,the changes of ATPase in kidney cell membrane using the method of biochemistry and molecule-biology(RT-PCR). This study includes the following five parts:1 The establishment for animal models of hypothyroid : Wistar rats weighted 120¹40gram after weaned 30 days,half of male and female,were divided into two groups randomly: low-iodine group(HYPO) and normal-iodine group (EU).HYPO group of rats were fed with low-iodine test diet (the concentration of iodine <50ug/kg) derived from an endemic goiter area,adding the necessary abio-salt and vitamins.EU group were fed the natrure mash.There had the same nutriments in the mash of two groups. HYPO rats drank deionized water (iodine concentration 0ug/ml ).EU rats drank tap water.2 Morphology of thyroid gland : Morphology of thyroid gland in rat were observed with HE staining.3 The serology determining: To take whole blood not anticoagu -lation 4ml of two groups,respectively,to centifuge and obtain the serum about 2ml,to determine the level of TT3,TT4,FT3,FT4 with competitive binding radioimmunoassary method.4 The capability of kidney antioxidation in hypothyroid rat: To take the kidney to measure the levels of free radical scavengers: GSH-PX(glutathione peroxidase),SOD(superoxide dismutase) and the major medium production of lipid peroxidation MDA (malondialdehyde) and activity of Na⁺,K⁺-ATPase,Ca²⁺-ATPase from euthyroid and hypothyroid groups.5 The expression of antioxidation gene in hypothyroid rats:Total RNA from fresh kidney using Trizol one-step-method were reversed transcribed to be cDNA. cDNA and different prime were mixed in PCR to amplificate target gene( GPx,SOD) and internal controlβ-actin gene.The product were fractionated on 1% agarose gels.The ratio of the intension of target gene to internal control were calculated.Results:1 The histological examination presented a typical defuse hyperplastic goiter in hypothyroid groups with features of dense follicles, small and irregular follicular cavities, high column shaped epithelial cells and decreased colloid, which indicating that marked compensation changes of thyroid function and morphology caused by long term of severe iodine deficiency.2 The TT₃,TT₄,FT₃ and FT₄ were all significantly decreased (P<0.01) in the HYPO group rats. We conclude that Wistar rats are suitable animals to product hypothyroid animal models,by the fact that hypothyroid Wistar rats have been produced successfully fed with the low-iodine diet and drank deionized water.3 The levels of MDA and GPx was increased(P<0.05), but the activity of SOD,Na⁺,K⁺-ATPase and Ca²⁺-ATPase was decreased (P<0.05) in HYPO group.We conclude that the reduced level of SOD over runs the compensated effect of GPx and causes excessive MDA ,which leads to peroxidation -induced damage to the renal tissue.4 The gene level results indicated : the levels of gene expression of GPx was increased little (no statistics meaning) ,and the levels of gene expression of SOD was decreased (P<0.05) in HYPO group. This approved at molecule level that there had peroxidation damage in kidney of hypothyroid rats.Conclusions:1 Low iodine induced hypothyroidism on Wistar rats. The histological examination presented a typical defuse hyperplastic goiter in hypothyroid groups with features of dense follicles, small and irregular follicular cavities 2 On hypothyroidism rat kidney , the activity of GPx was compensated increased ,the reduced level of SOD not to scavenge the excessive free radical. Thus the content of MDA in kidney was increased,and Ca²⁺-ATPase and Na⁺,K⁺-ATPase was decreased。3 On hypothyroidism rat kidney,the gene expression of GPx -mRNA increased little (no statistics meaning) and SOD-mRNA was decreased significantly.4 The mechanism of hypothyroidism kidney damagewere probable due to the excessive free radicals,it leaded to peroxidation-induced damage to the cell.