Objective: To investigate the protective effects and mechanisms of quercetin on myocardial cell in diabetic rats. Methods: Male Spregue-Dawley rats were randomly divided into four groups: control group, diabetes group, intervention group with low dose quercetin(50 mg/kg gavage), intervention group with high dose quercetin(100 mg/kg gavage). All groups received streptozocin (STZ) by intraperitoneal injection to induce type 1 diabetes mellitus model expect for control group. After gavage for 1 month, cardiac functions were tested by echocardiography. The ratios of cardiomyocyte apoptosis were detected by TUNEL staining. The protein expression of B-cell lymphoma-2 associated X (BAX), B-cell lymphoma-2 (BCL-2), phosphorylated protein kinase B (pAKT), AKT, phosphorylated forkhead box O3 (pFOXO3), FOXO3 were tested by Western blotting. The mRNA levels of Bax and Bcl-2 were tested by quantitative real-time PCR. Results: The cardiac function of diabetes group reduced compared to control group, but ejection fraction and fractional shortening increased in intervention group with low dose quercetin and intervention group with high dose quercetin (P<0.05). The ratios of cardiomyocyte apoptosis in diabetes group were higher than control group (P<0.05), but it decreased in intervention group with low dose quercetin and intervention group with high dose quercetin (P<0.05). There were no obvious changes between intervention group with low dose quercetin and intervention group with high dose quercetin (P>0.05). The mRNA and protein expression of Bax in diabetes group were higher than that in control group (P<0.05), but they reduced in intervention group with low dose quercetin and intervention group with high dose quercetin compared to diabetes group (P<0.05). The mRNA and protein expression of Bcl-2 in diabetes group were lower than control group (P<0.05), but they increased in intervention group with low dose quercetin and intervention group with high dose quercetin compared to diabetes group (P<0.05). The protein expression of pAKT and pFOXO3 in diabetes group were lower than control group (P<0.05), but they increased in intervention group with low dose quercetin and intervention group with high dose quercetin (P<0.05), there were no obvious changes in AKT and FOXO3 between four groups (P>0.05). Conclusion: Quercetin can reduce apoptosis of myocardial cell in diabetic rats through activating AKT/FOXO3 signaling pathway, thus restore the cardiac function.

［Key words］diabetes; quercetin; myocardial cell; apoptosis; AKT/FOXO3 signalling pathway