| Objective:To clarify the mechanism of doxorubicin cardiotoxicity, providing important theoretical and experimental data to find effective drug used for prevention and treatment of DOX cardiotoxicity.Methods:24 male SD rats with 6 to 8 weeks were used in the experiment model,6 rats in each group. The animals were randomly divided into four groups: group administered 5 times(DOX5), administered 10 group(DOX10), 5 times a saline control group(NS5), 10 times the saline control group(NS10). Animals of DOX10 group were given DOX(2.0mg / kg, ip). Animals of NS10 group were given an equal volume saline(Normal Saline, NS). They were administered twice each week and 10 times totally. Animals of DOX5 and NS5 groups were given five times DOX or NS. Every time after the last administration and a washout period of 14 days, the rats were killed by cervical dislocation method of rat thoracic cleaning, rapid removal of the heart. We got the myocardial tissue of mice to detect catalase(CAT), superoxide dismutase(SOD) activity, lipid peroxidation product malondialdehyde(MDA), to observe the degree of oxidative damage of heart. We used Western blot analysis to detect myocardial apoptosis-related protein Caspase-3 expression signaling factors, Bcl-2, Bax protein and calculated Bcl-2 / Bax to understand apoptosis.Results: 1 Results of Cardiomyocyte morphologySome regional myocardial fibers in DOX experimental group than that in control group were stripes missing or disappeared, even nuclear migration disappeared, muscle fiber edema, the gap widened, derangement, inflammatory exudation factor, and DOX10 group than DOX5 group was more obvious. 2 Results of catalase(CAT)detection in each groupCatalase activity of each group were: NS5 group(37.27 ± 1.39) U / mg protein, DOX5 group(29.00 ± 1.15) U / mg protein, NS10 group(36.31 ± 1.05) U / mg protein, DOX10 group(24.41 ± 1.13) U / mg protein.CAT of DOX group content was less than NS group, the difference was statistically significant(P <0.05). CAT of DOX10 experimental group content was below DOX5 experimental group, the difference was statistically significant(P <0.05). 3 Results of superoxide dismutase(SOD) detection in each groupSuperoxide dismutase(SOD) detection results of each group were: NS5 group(28.50 ± 0.54) U / mg protein, DOX5 group(23.40 ± 0.59) U / mg protein, NS10 group(27.80 ± 0.25) U / mg protein, DOX10 group(19.20± 0.47) U / mg protein.SOD of DOX group content was less than NS group, the difference was statistically significant(P <0.05). SOD of DOX10 experimental group content was below DOX5 experimental group, the difference was statistically significant(P <0.05). 4 Results of malondialdehyde(MDA) detection in each groupMalondialdehyde(MDA) detection results of each group were: NS5 group(2.86 ± 0.21) nmol/mg protein, DOX5 group(6.93 ± 0.39) nmol/mg protein, NS10 group(3.04 ± 0.31) nmol/mg protein, DOX10 group(12.00 ± 0.14) nmol/mg protein.MDA of DOX group content was much than NS group, the difference was statistically significant(P<0.05). MDA of DOX10 experimental group content was above DOX5 experimental group, the difference was statistically significant(P<0.05). 5 Results of Caspase-3, Bcl-2, Bax expression detection 5.1 Caspase-3Results of Caspase-3 expression in each group were: NS5 group 14.33 ± 1.59, DOX5 group 24.21 ± 1.30, NS10 group 13.39 ± 3.13, DOX10 group 34.18 ± 1.14.Caspase-3 of DOX group was much than the NS group, the difference was statistically significant(P <0.05). Caspase-3 of DOX10 group was much than DOX5 group, the difference was statistically significant(P <0.05). 5.2 Bcl-2/BaxResults of Bcl-2 expression in each group were: NS5 group 24.34 ± 2.80, DOX5 group 17.42 ± 1.19, NS10 group 26.46 ± 1.34, DOX10 group 15.78 ± 2.48.Results of Bax expression in each group were: NS5 group 15.38 ± 1.15, DOX5 group 24.04 ± 1.62, NS10 group 14.94 ± 2.47, DOX10 group 28.97 ± 1.73.The ratio of Bcl-2/Bax in each group were: NS5 group 1.58± 2.43, DOX5 group 0.72 ± 0.73, NS10 group 1.77 ± 0.54, DOX10 group 0.54 ± 1.43.The ratio of Bcl-2 / Bax in DOX5 was lower than the control groups, the difference was statistically significant(P <0.05). The ratio of Bcl-2 / Bax in DOX10 was lower than the control group, the difference was statistically significant(P <0.05). The ratio of Bcl-2 / Bax in DOX10 experimental group was lower than DOX5 experimental group, the difference was statistically significant(P <0.05).Conclusion:1 After DOX administration, CAT and SOD were significantly reduced, indicating that in vivo antioxidant system has been damaged. After DOX administration, MDA content increased significantly, that DOX causing severe oxidative damage to the body. With the increase of the cumulative dose, oxidative damage increased.2 Compared with the control group, after DOX administration, pro-apoptotic factor,expression of Caspase-3 increased. Bax expression increased, while the anti-apoptotic factor Bcl-2 expression decreased, Bcl-2 / Bax ratio also decreased significantly, indicating that DOX can cause myocardial apoptosis. Toxic effects of oxidative stress mediated DOX heart may be related to inducing apoptosis of myocardial cells. |
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