| Objective: To explore NOX2.NOX4-mediated pre-protection effect of valsartan-on rats with adriamycin induced cardiomyopathy and it related mechanism.Methods: Forty of male Sprague-Dawley(SD)rats,mass(170 ± 10)g with special pathogen free animal(SPF)grade were selected.,those rats were randomly divided into three groups.The model was established after a week of adaptive feeding.Model group(n = 18): 0.9% sodium chloride was used to prepare adriamycin solution of 2mg/ml which was injected into intraperitoneal by 1.25ml/kg.BW,once a week for6 weeks.The rats were rinsed with 0.9% sodium chloride by 2ml/kg.BW and the dose was re-adjusted weekly according to their weight.Valsartan intervention group(n =14): Valsartan was given the same treatment as model group.0.9% sodium chloride was applied to prepare valsartan solution of 10 mg/ml which was administered by 2ml/kg.BW once a day for 6 weeks,and the dose was re-adjusted weekly according to their weight.The rats in the normal control group(n = 8)were injected intraperitoneally with equal volume of normal saline,and administered the same amount of sodium chloride.The three groups,under the same feeding conditions,were observed for 10 weeks after drug intervention.Results: After ten weeks,the survival rate of the control group,model group and valsartan intervention group were respectively 100%(8/8),66.66%(12/18)and85.71%(12/14).Echocardiogram: the left ventricular ejection fraction(LVEF)in the model group,the valsartan group and the normal control group were(60.36 ±13.54)%,(75.31 ± 10.39)% and(89.11 ± 2.09)%.Compared with the control group,LVEF in the other two groups were lower,but LVEF in valsartan group was significantly higher than that in the model group(P <0.05).The LVFS in the control group,the model group and the valsartan intervention group were(60.44±6.61)%,(30.84±10.68)% and(58.15±13.34)%.It can be found that LVFS in the control group was significantly higher than that in model group(P <0.05)and fewdifferences were seen between the control group and the valsartan group(P> 0.05).Left ventricular end-systolic dimension(LVESD)were(2.70±1.02)mm,(2.48±0.89)mm and(1.38±0.52)mm in the model group,the valsartan group and the normal control group.Model group and valsartan group were found to have significantly higher LVESD than that of the normal control group,which was statistically significant(P<0.05).There was no significant difference in the comparison of left ventricular end diastolic diameter(LVEDD)among the three groups.Histopathological examination:HE staining: orderly cardiac myocytes arrangement and even staining without swelling and fracture can be seen in thel control group;In the model group,multifocal myocardial fibers were arranged disorderly with thinning,dissolved rupture,interstitial edema and cardiomyocyte vacuolar changes.In the valsartan intervention group,myocardial cells were arranged neatly,and local muscle dissolution and a small part of the interstitial fluid swelling were seen.Sirius red staining: collagen fiber was red and myocardial fiber was yellow.In the normal control group,the myocardial fibers were arranged orderly,and a small amount of scarlet collagen fibers can be seen around the myocardium and the blood vessels.In the model group,the structure of the myocardial fibers was disordered,and the red collagen fibers were distributed around the vascular and myocardial fibers.In the valsartan intervention group,no swelling and fracture of myocardial fibers can be found,and the scarlet muscle collagen fibers were scattered around the blood vessels.ELISA was used to detect the protein expression of 6 indexes in myocardium related.The contents of Renin(ng/ml)were(27.19±2.26),(41.79±3.70)and(27.19±2.26)in the normal group,the model group and the valsartan intervention group.We can see that Renin in the valsartan group was higher than that of the other two groups,which was statistically significant(P<0.05),and Renin in the valsartan group rose compared with that in the contract group,which was also statistically significant(P<0.05).The levels of angiotensin ?(ng/ml)in the normal group,the model group and the valsartan intervention group were(341.94±51.35),(413.75±69.03)and(348.10±66.97)),and the levels of ALD(ng/ml)were(246.25 ± 68.02),(376.75 ± 85.27)and(264.23 ±71.03);ROS's contents(ng/ml)were(275.35±71.82),(355.58±100.13)and(327.38±69.79),and the contents of malondialdehyde MDA(ng/ml)were(2.55±0.72),(3.99±0.93)and(2.72±0.77).The above four indicators were found to be lower in the normal control group than the model group(P <0.05),be higher in the model group than the other two groups and have fewer differences in the normal and valsartan group.The levels of superoxide dismutase SOD(ng/ml)in the myocardium were(144.57±32.13),(105.41±22.56)and(138.846)in the normal control group,the model group and the valsartan intervention group.SOD in the valsartan group was higher than that in the model group which was statistically significant(P <0.05).There was no significant difference between the model group and the normal group(P>0.05).According to the analysis of Western blot,the expression of NOX2 protein were(0.73 ± 0.12),(0.44 ± 0.05)and(0.22 ± 0.03)respectively in the model group,valsartan intervention group and normal control group.The expression levels of NOX4 were(0.94 ± 0.18),(0.65 ± 0.05)and(0.36 ± 0.02).There was significant difference between any of the two groups among three(p <0.05).The expression of NOX2 and NOX4 protein in the model group were higher than that in the valsartan intervention group,while the expression of NOX4 in the model group was higher than that in the normal group.Valsartan intervention could significantly decrease the expression of NOX2 and NOX4 in myocardium of adriamycin-induced cardiomyopathy rats.Conclusion: The study of SD rats model with Adriamycin induced cardiomyopathy and that with valsartan intervention,not only reflects the characteristics of cardiac damage in rats from general condition,cardiac ultrasonography,pathology and so on;but shows that valsartan can reduce cardiotoxicity caused by doxorubicin,improve the systolic function of the heart,and protect the heart through the inhibition of doxorubicin-induced excessive oxidative stress by NOX2,NOX4-mediated pathway system in the NOX subtype. |
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