Investigation On DM Rats Thyroid Ultrastructure And Thyroid Function-relative Factors MRNA Expression Change And Intervention

Objectives:Diabetes mellitus (DM) is a metabolic disorder of chronic hyperglycemia which is caused by multitude factors. There are other dyscrinisms, besides insulin in DM. Epidemiological studies showed there were more thyroid paramorphia and disfunction in type 2 DM than normal. There is relationship between AGEs (advanced glycation end products)-RAGE (receptor of AGEs) system and DM chronic complications. It is not reported the effection of AGEs-RAGE system on DM rats thyroid. AG (aminoguanidine) and INS(insulin) block the effection of AGEs-RAGE system in different ways. In this study, we observed rats thyroid ultramicrostructure and detected the expressions of RAGEmRNA, TSHR mRNA, NIS mRNA, TG mRNA and TPOmRNA in different times and different groups. The groups include①without treatment(DM);②AG treatment(DA);③insulin treatment(DI);④controls(N).We investigate the change of ultrastructure and thyroid function in thyroid of DM rats and the intervention effect of AG and INS.Methods:112 male wistar rats(210-255g body weight) were divided randomly into T2DM experiment group(n=87) and N group (n=25). N group were fed with normal animal feeds. After fed with high fat diet for eight weeks, T2DM experiment group were injected with 30 mg streptozocin /kg BW via the tail vein. N rats was injected by buffer solution. Blood samples were taken from canthus veins for glucose test in 72 hours. The glucose levels of experiment group rats were more than 16.65mmol/L. T2DM experiment group were devided randomly into three groups.That was①DM (n=27);②DI (n=32);③DA (n=28). DI rats were treated with protamine zinc insulin(6U/kg.d) via hypodermic injection. DA were treated with AG(50mg/kg.d)via intragastric administration.Then 12weeks,20 weeeks later after administration,rats were sacrificed, and the thyroid samples were obtained.①Put them in the solution of the 2.5% glutaric dialdehyde and 1% osmium tetroxide to fixate, and then observed with JEM100CX II transmission electron microscope.②Put them in the liquid nitrogensolution to fixate, and then extracted RNA. Detected the mRNA expression of RAGE,TSHR,NIS,TG,TPO by reverse transcription-polymerase chain reaction(RT-PCR). Results:①Body weight:DM group are lower than DA group, DI group and N group (p<0.01),there are no statistical difference among the three latter groups; Blood sugar:DM group, DA group and DI group are higher than N group(p<0.01), there are no statistical difference between DA group and DM group, but they are higher than DI group(p<0.01)②Ultrastructure:The thyroid tissue of DM group rats displayed that follicular epithelial cells were injured and hypofunction. vascular endothelium are injured, basilemma are thickened, inflammatory cells infiltrate, fiber hyperplasia. The degree of injures increase with the disease course; The thyroid ultrastruture injuries of DA group are lighter than DM group, and that of DI group are lighter than DM and DA group.③RT-PCR:RAGE:DM group is higher than DI group,DA group,N group(p<0.01);DA group is lower than DI group(12weeks, p <0.05,20weeks, p<0.01), there is no statistical difference between DA group and normal group; DI group is higher than N group(p<0.01).TSHR:12weeks:DM group is higher than DA group (p<0.01),DI group(p<0.01)and N group (p<0.05);DA group is lower than DI group(p=0.894), higher than N group (p=0.239);DI group is higher than N group (p=0.197).NIS:DM group is lower than DA group(12weeks,p <0.01,20weeks, p=0.075),DI group (12weeks, p<0.01,20weeks, p=0.969),N group(12 weeks and 20 weeks, p<0.01);DA group is lower than DI group(12 weeks and 20 weeks, p<0.001), N group (12weeks,p=1.000,20weeks, p=0.002);DI group is lower than N group(12 weeks p=1.000,20weeks p=0.155).TG:20 weeks:DM group is lower than DA group, DI group, N group(p<0.01);DA group is higher than DI group(p=0.751) and lower than N group(p=0.675),DI group is lower than N group(p=0.426).TPO:DM group is lower than DA group(12weeks,p<0.01,20weeks, p=0.505),DI group(p<0.01),N group (p<0.01);DA group is lower than DI group and N group(p<0.01);DI group is lower than N group(p<0.01).Conclusions:①The model of type 2 diabetic rat could be made by short period high fat diet then small amounts streptozocin via the tail vein.②DM group rats:Thyroid tissue ultrastructure was damaged, revealed hypofunction. RAGE and TSHR mRNA expression increased,NIS,TPO and TGmRNA expression decreased. It is indicated thyroid damage may be related with RAGE overexpression.③Thyroid ultrastructure and function of DA group improved, RAGEmRNA expression decreased. It indicated that AG can decrease thyroid RAGEmRNA expression, extenuate thyroid injury that caused by hyperglycemia toxicity.④DI group rats blood sugar decreased markedly, thyroid ultrastructure and function improved, RAGEmRNA expression decreased. It indicated that insulin supplement can lower blood sugar, decrease RAGE expression, protect thyroid from hyperglycemia toxicity.⑤When compared with DA group, DI group displayed thyroid injury are lighter, RAGEmRNA expression are higher. This indicated that insulin can extenuate DM thyroid injury through other mechanisms, except from suppression in expression of RAGEmRNA.