The Effect Of Combination Of Tandospirone And Valsartan On Blood Pressure And Myocardial Fibrosis In Spontaneously Hypertensive Rats

Objective:The aim of this study is to investigate the advantage of combination of tandospirone and valsartan on blood pressure and myocardial fibrosis in spontaneously hypertensive rats and its associated mechanism.Methods:3212w-male SHRs were randomized into four groups,namely SHR model group(SHR group,1 ml·100g^-1·d^-1,distilled water,n=8),tandospirone group(SHR+Tan group,40 mg·kg^-1·d^-11 tandospirone,n=8),valsartan group(SHR+Val group,30 mg·kg^-1·d^-11 valsartan,n=8)and the combination regimen group(SHR+Tan+Val group,40 mg·kg^-1·d^-11 tandospirone plus 30mg·kg^-1·d^-11 valsartan).Eight male Wistar-Kyoto rats at the same age with normal blood pressure were served as blank control group(WKY group,1ml·100g^-1·d^-1,distilled water,n=8).The automatic noninvasive blood pressure measurement system was used to measure the tail artery systolic and diastolic blood pressure of all rats before and 1 h,2 h,3 h,4 h,1 w,2 w,3 w,4 w,5 w,6w,7 w,8 w after drug administration.After the final administration,all rats suffered 24 h fasting with free access to water.After weighing?BW?,all rats were anesthetized with an intraperitoneal injection of 10%chloral hydrate.All hearts were harvested rapidly,the left ventricle with interentricular septumw were carefully isolated and weighed?LVM?and the left ventricular mass index?LVMI?was calculated.Then,the left ventricle was transversed into three parts:apex,middle ring and the base,and they were put into RNAwait,10%neutral formalin and-80?ultra-low temperature freezer,respectively.Left ventricular myocardium stored in 10%neutral formalin were used for HE and Masson staining to observe the pathological changes of myocardium,and the immunohistochemistry to determine the protein expression of TGF?1,Smad3and Fibronectin?Fn?.Left ventricular myocardium stored in-80?ultra-low temperature freezer were used for detecting the protein expression of TGF?1,Smad3 and Fn by Western blot.Left ventricular myocardium stored in RNAwait were used for determining the gene expression of TGF?1,Smad3 and Fn by fluorogenic quantitative PCR.Results:?1?Before drug administration,the tail artery systolic blood pressure?SBP?of SHRs were significantly higher than the Wistar-Kyoto rats?P<0.01?.After 1h of drug administration,compared with the SHR group,the rats'SBP in the SHR+Tan group,the SHR+Val group and the SHR+Tan+Val group were significantly decreased?P<0.01?,and compared with the the SHR+Val group,the rats'SBP in the SHR+Tan+Val group declined more significantly?P<0.05?.The antihypertensive effect of all the drug delivery groups lasted 4 h after administration?P<0.01?,and the antihypertensive effect of combined administration was significantly better than that of the SHR+Val group after the administration of 1 h,2 h and 3 h?P<0.05or P<0.01?.Before drug administration,the tail artery diastolic blood pressure?DBP?of SHRs were significantly higher than the Wistar-Kyoto rats?P<0.01?.After 1 h of drug administration,compared with the SHR group,the rats'DBP in the SHR+Val group and the SHR+Tan+Val group decreased significantly?P<0.01?,and the antihypertensive effect of both groups lasted 4 h after administration?P<0.01?.After 2 h of drug administration,compared with the SHR group,the rats'DBP in the SHR+Tan group decreased significantly?P<0.05?,and the antihypertensive effect lasted 4 h after administration?P<0.01?.Compared with the SHR+Val group,the DBP of the rats in SHR+Tan+Val group decreased,but the difference was not statistically significant.After 1 w continuous administration,compared with SHR group,the SBP in SHR+Tan group?the SHR+Val group and the SHR+Tan+Val group were significantly decreased?P<0.01?.The antihypertensive effect of each drug delivery group continued until 8 weeks?P<0.05 or P<0.01?.At the seventh and the eighth week,compared with the SHR+Val group,the SBP of SHR+Tan+Val decreased significantly?P<0.05 or P<0.01?.After 1w continuous administration,compared with SHR group,the DBP in SHR+Tan group,the SHR+Val group and the SHR+Tan+Val group were significantly decreased?P<0.01?.The antihypertensive effect of each drug delivery group continued until 8 weeks?P<0.05 or P<0.01?.At the eighth week,compared with the SHR+Val group,the SBP of SHR+Tan+Val decreased significantly?P<0.01?.?2?The LVMI of SHR group was significantly higher than that of WKY group?P<0.01?.Compared with the SHR group,SHR+Val group and the SHR+Tan+Val group significantly reduced the LVMI?P<0.01?,but there was no significant difference between SHR+Val group and the SHR+Tan+Val group.?3?HE staining showed that compared with WKY group,the hypertrophy of myocardial cell in SHR group was rather serious,and compared with the SHR group,individual treatment can improve the cardiac hypertrophy of SHR rats in different degrees,and the effect of combination therapy was more obvious.?4?Masson staining showed that compared with WKY group,the myocardial interstitial fibrosis in SHR group was rather serious,and compared with SHR group,individual treatment can improve the proliferation of myocardial fibers of SHR rats in varying degrees,and the effect of combination therapy was more notable.?5?The results of fluorescent quantitative PCR showed that the mRNA expression of TGF?1,Smad3 and Fn in SHR group were significantly higher than that of WKY group?P<0.01?,and compared with SHR group,the gene expression of TGF?1,Smad3 and Fn were significantly declined in each drug delivery group?P<0.01?.There was no statistical difference between the SHR+Tan+Val group and the SHR+Val group.?6?The semiquantitative analysis of immunohistochemistry showed that the protein expression of TGF?1,Smad3 and Fn in SHR group were significantly higher than that of WKY group,and compared with the SHR group,the protein expression of TGF?1,Smad3 and Fn decreased in each drug delivery group?P<0.05 or P<0.01?.There was no statistical difference between the SHR+Tan+Val group and the SHR+Val group.?7?The quantitative results of Western blot showed that the the protein expression of TGF?1,Smad3 and Fn in SHR group were significantly higher than that of WKY group,and compared with the SHR group,the protein expression of TGF?1,Smad3 and Fn decreased in each drug delivery group?P<0.05 or P<0.01?.Compared with the SHR+Val group,the protein expression of TGF?1 and Smad3 of SHR+Tan+Val group both decreased significantly?P<0.05 or P<0.01?.There was no statistical difference between the SHR+Tan+Val group and the SHR+Val group on the protein expression of Fn.Conclusion:1.Tandospirone citrate combined with valsartan could lower blood pressure,reduce left ventricular mass index,and reverse cardiac hypertrophy and myocardial fibrosis in spontaneously hypertensive rats.2.The effect of combination of tandospirone and valsartan on the improvement of myocardial fibrosis may be mediated by decreasing the protein expression of TGF?1,Smad3 and Fn,and lowering the gene expression of TGF?1,Smad3and Fn.