The Effect Of Excessive Intake Of Iodine On Activation Of Inferior Vena Cava Endothelial Cells Of Rats

[Objective]In this study, Wistar rats were fed with excessive Iodine and monophagia diet to establish a rat model of excessive Iodine and monophagia diet. Hematoxylin-Eosin Staining was done to observe endothelial morphological change of liver period of the Inferior Vena Cava of rats. Related factors from plasma of rats were determined and immunohistochemical staining was done to observe the activation of Endothelial cells(ECs) and discuss the mechanism causing endothelial cell activation by excessive Iodine.[Material and Methods]1. Experimental animals and groups:SPF/VAF Wistar rats of outbreeding closed colony, about1month after weaning, weighing (110±10)g,were purchased from the Animal Experimental Center, Shandong University,and were randomly divided into8groups according to weight and sex after a week of Adaptive feeding, the order was as follows:①normal control group(NC);②10-multiple excessive Iodine group(10HI);③50-multiple excessive Iodine group(50HI);④100-multiple excessive Iodine group(100HI);⑤monophagia control group(MC);⑥10-multiple excessive Iodine and monophagia group(M10HI);⑦50-multiple excessive Iodine and monophagia group(M50HI);⑧100-multiple excess Iodine and monophagia group(M100HI),8rats in each group.2. Records of weight of the rats:The above rats were weekly weighed and recorded.3. Hematoxylin-Eosin Staining of liver period of the Inferior Vena Cavain of rats:10%formalin fixed, conventionally paraffin embedded, cut into slice, xylene dewaxed, hydrated at all levels by ethanol, haematoxylin stained2minutes, hydrochloric acid alcohol differentiated15s, eosin and alcohol stained2-5minutes, conventionally dehydrated and transparent, sealed, then endothelial morphological change was observed.4. ET-1, vWF, vWFpp and HCY from plasma of rats were determined using Elisa kits.5. Immunohistochemical chemistry of liver period of the Inferior Vena Cava in rats: tissue sections were dewaxed and hydrated, repaired antigen, PBS washed, dropped primary antibody and second antibody,then DAB colored. Expression of E-selection and ICAM-1in endothelial cells of the Inferior Vena Cava was observed.[Results]1. Changes of body weights of rats:From start to6th month, weights of each single high iodine group showed no obvious difference from that of NC group; weights of monophagia control group (MC) did not appear statistical differences from that of NC group until6th month. From2ed week, weights of each excessive iodine and monophagia groups,containing M10HI group,M50HI group and M100HI group, were lower or significantly lower than that of NC group.2. Endothelial morphological change:With the gradual increase of the iodine concentration, endothelial cells of the Inferior Vena Cava appeared changes of activation and proliferation, characterized by protrusion of ECs into the lumen of blood vessels, hypertrophy of ECs (plump cuboidal appearance), increased number of ECs, increased ECM out of ECs, and even thickening of the venous wall, with monophagia groups more obvious.3. Change of ET-1、vWF、vWFpp and HCY in plasma of rats3.1Change of ET-1in plasmaTo a certain extent, endothelial function was affected. Compared with normal control group, ET-1increased in50HI group (p<0.05), and significantly increased in100HI group, M50HI group and M100HI group (p<0.01). Comparison between groups showed expression of ET-1gradually increased with the gradual increase of the iodine concentration (P<0.05or P<0.01)3.2Change of vWF in plasmaEndothelial function was affected. Compared with normal control group, vWF increased in M10HI group and M50HI group (p<0.05), and significantly increased in100HI group and M100HI group (p<0.01). With the gradual increase of the iodine concentration, expression of vWF gradually increased. VWF increased in M10HI group compared with MC group (P<0.05),vWF significantly increased in100HI group and M100HI group compared with50HI group and M50HI group respectively(P<0.01).3.3Change of vWFpp in plasmaVWFpp increased in M50HI group (p<0.05), with no change in other groups.3.4Change of HCY in plasmaCompared with normal control group, HCY increased in50HI group (p<0.05), and significantly increased in100HI group, M10HI group, M50HI group and M100HI group(p<0.01). Comparison between groups showed HCY gradually increased with the gradual increase of the iodine(P<0.05or P<0.01).4. Immunohistochemical results4.1Expression of ICAM-1With the gradual increase of iodine concentration, endothelial expre-ssion of ICAM-1increased.Compared with normal control group, expre-ssion of ICAM-1in M100HI group showed statistical difference (P<0.05); Comparison between groups showed no statistical difference (P>0.05).4.2Expression of E-selectionWith the gradual increase of iodine concentration, endothelial expression of E-selection increased. Compared with normal control group,expression of E-selection in100HI group, M50HI group and M100HI group showed statistical difference (P<0.05or P<0.01); Comparison between groups:expression of E-selection in M100HI group showed statistical difference compared with M10HI group (P<0.05).[Conclusions] 1.Endothelial morphological change shows that excessive iodine can result in endothelial cell activation, damage and hyperplasia, ECM increase, and even thickening of the venous wall, with time-dose effect and more obvious change in monophagia groups, which suggests that excessive iodine can cause thickening and luminal stenosis of the inferior vena cava wall by promoting endothelial cell activation, injury and hyperplasia in this animal model,which might play a role in the pathogenesis of membrane-type budd-chiari syndrome syndrome.2. Excessive iodine can make many factors in plasma change,including ET-1、vWF and HCY. With the gradual increase of the iodine concentration, ET-1、vWF and HCY in plasma increases.Besides, excessive iodine can make expression of E-selection and ICAM-1in ECs increase,which are markers of endothelial cell activation.3. In the animal model, monophagia diet induced malnutrition can strengthen the effect of high iodine on endothelial cell activation in inferior vena cava of rats.