Objective To investigate the oxidative stress status and cardiac myocyte apoptosis in rats with propylthiouracil-induced hypothyroidism and to examine the effect of levothyroxine ( LT4 ),vitamin E ( VitE ),and both supplementation on this experimental model.Methods Male Sprague Dawley rats were divided into normal control group( NC),propylthiouracil group( PTU ),LT4 treatment group( PTU + LT4 ),VitE treatment group ( PTU +VitE),LT4 and VitE combination therapy group (PTU + LT4 + VitE).Serum T3,T4,TSH levels,serum and myocardial superoxide dismutase ( SOD ) activity and malondialdehyde ( MDA ) content were determined.Cardiac myocyte apoptotic index was made with TUNEL.Results ( 1 ) Compared with NC group,T3 and T4 levels were significantly lower and TSH level was significantly higher in PTU group and PTU+VitE groups( P＜0.05 ).Compared with PTU group,T3 and T4 levels were significantly higher and TSH level was significantly lower in PTU + LT4 group and PTU + LT4 + VitE group( P＜0.05 ).There were no statistical differences in T3,T4,and TSH levels between PTU group and PTU + VitE group( P＞0.05 ).( 2 ) Compared to NC group,serum and myocardial MDA levels in PTU group increased significantly( P＜0.05 ),serum SOD activity decreased significantly ( P＜0.05 ),while myocardial SOD activity showed no significant difference( P＞0.05 ).( 3 ) Compared with NC group,myocardial apoptosis index was significantly higher in PTU and PTU + VitE groups( P＜0.05 ).Compared with PTU group,myocardial apoptosis index was significantly lower in PTU + LT4 group and PTU + LT4 + VitE group( P＜0.05 ).Conclusion LT4,VitE,and their combined treatment of hypothyroidism in rats reduce the myocardial cells apoptosis,which may be related to the improvement of thyroid function and amelioration of oxidative stress.