ObjectiveTo investigate the influence of recombinant thioredoxin (TRX)on apoptosis of myocardium cell in viral myocarditis of mice.MethodsTwenty-four Balb/c mice,weighting 12 - 14 g,were randomly divided into 3 groups:the control group,the virus group and the protective group,8 mice in each group.The virus group and the protective group were injected with 0.1 ml 100TCID50 Coxackie virus B3 (CVB3)intraperitoneally,and the control group was injected equal volume of saline.Therewithal the protective group was injected with TRX(2 mg/kg) by tail vein,and the virus group was injected saline the same way.After 14 days all mice were killed and hearts were taken.Changes of myocardial histopathology was observed with optical microscope,cell apoptosis was checked by TUNEL technique,and the expression of apoptosis-related proteins (Bcl-2,caspase-3)in infiltrated cell of myocardium was determined by immunohistochemistry.Results(①)Lymphocyte infiltration and necrosis were observed in survivals of the virus group,sporadic coagulation necrosis and ballooning degeneration of cells were observed in the protective group,however no myocardial lesion was found in the control group.(②)TUNEL technique showed that the positive ratio of apoptosis in the virus group and the protective group[(90.23 ± 3.63)％,(20.02 ± 2.41)％] was significantly higher than that of the control group(0.00 ± 0.00,all P ＜ 0.05),the positive ratio of apoptosis in the protective group was significantly lower than that of the virus group (P ＜ 0.05 ).(③)Immunohistochemistry showed that the expression of protein Bcl-2(+,++,+++) in the virus group and the protective group was significantly higher than that of the control group (all P ＜ 0.05).The expression of protein Bcl-2 in the protective group was significantly higher than that of the virus group(P ＜ 0.05).The expression of caspase-3 (+,++) was significantly higher in the virus group and the protective group than the control group (all P ＜ 0.05).Compared with the virus group,the expression of caspase-3 in the protective group was significantly lower(P ＜ 0.05).ConclusionTRX could inhibit cardiomyocyte apoptosis in viral myocarditis mice and the inhibition is related to regulation of apoptosis-related protein expression.