Aim To evaluate the effects of dietary iodine intake on the development of atherosclerosis in mice and to further investigate the association between iodine and cardiovascular disease.Methods Female C57BL/6 mice,weaning 1 month and weighing around 16 g,were randomly divided into five groups according to the iodine intakes:severe iodine deficiency(SID),mild iodine deficiency(MID),normal iodine(NI),10-fold high iodine(10 HI)and 50-fold high iodine(50 HI).All the mice were fed by high fat high cholesterol low iodine fodder(HFHCLI,iodine content is 20～40 μg/kg)and drank deionized water containing different concentrations of potassium iodide including 0 μg/L(SID),196.08 μg/L(MID),326.79 μg/L(NI),3 856.21 μg/L(10 HI)and 19 542.5 μg/L(50 HI)respectively.Eight months later,all the animals were sacrificed.Serum thyroid hormones(total T4 and total T3)were measured by radio immunoassay.The levels of triglyceride(TG),total cholesterol(TC),high density lipoprotein cholesterol(HDLC),low density lipoprotein cholesterol(LDLC)in the serum were detected enzymatically by automatic analysis.The extent of lesion development in the proximal aorta or aortic root was observed by hematoxylin-eosin staining on the paraffin-embeded tissue slides.Real-time PCR was applied to detect the expressions of intercellular adhesion molecule-1(ICAM-1)mRNA and vascular cell adhesion molecule-1(VCAM-1)mRNA in aorta and low-density lipoprotein receptor(LDLR)mRNA in liver.Results(1)The levels of thyroid hormones(total T4 and total T3)were distinctively decreased in SID and MID,especially in SID,compared with NI group(P><0.01 or P><0.05).(2)The levels of TG,TC and LDLC in SID and LDLC in MID were obviously higher than that in NI group(P><0.01).In contrast,the levels of TC in both 10 HI and 50 HI groups were statistically lower than NI group(P><0.01).(3)Pathological changes showed that in the tunica intima,sub-endothelial space was obviously wider with lipids deposition in NI.In MID and SID,sub-endothelial space was progressively wider and foam cells were found in regional area with some lipids around them,called fatty streak formation.In 10 HI and 50 HI group,sub-endothelial space was just slightly wider and the staining was pale.(4)Both ICAM-1 and VCAM-1 mRNA in the aorta tissues were highly expressed in SID than NI group(P><0.01).Similarly,the expression level of ICAM-1 mRNA in MID group was higher than NI group(P><0.01).In contrast,much lower expressions of these adhesion molecules were detected in 50 HI group compared with NI group(P><0.01 or P><0.05).The expression levels of LDLR mRNA in liver in SID and MID group were much lower while higher in 10 HI and 50 HI group than NI group(P><0.01 or P><0.05).Conclusion Dietary iodine intake could influence the development of atherosclerosis in mice fed by lipid-enriched diets by regulating thyroid function,the metabolism of serum lipids and the gene expression in liver.Iodine deficiency can have deleterious effects on the cardiovascular system,and a higher iodine intake may benefit it.