| Objective:1)To explore the effect of chronic exposure to nonylphenol(NP)on myocardial fibrosis and cardiac function in rats,and sensitive indicators that NP induces cardiotoxicity.2)To explore whether zinc-selenium tea have an intervention effect on myocardial fibrosis caused by NP.Methods:Sixty SD male rats were randomly divided in to 6 groups: Control group(C,corn oil),low NP dose(L,0.4 mg/kg),NP medium dose(M,4 mg/kg)NP high dose(H,40 mg/kg)groups,green tea intervention group(0.2 g/ml),zinc-selenium tea intervention group(0.2 g/ml).The rats were given daily by gavage according to its body wight(gavage volume: 5 ml/kg/d).All treatment groups were subjected to continuous intragastric administration for 180 days.The tea intervention group were exposed to NP the dose of 40 mg/kg.Doppler ultrasound was used to observe the changes of cardiac structure and function including left ventricular anterior wall(LVAWd),systolic thickness of the left ventricular anterior wall(LVAWs),left ventricular end diastolic diameter(LVIDd),left ventricular end systolic dimensions systolic dimensions(LVIDs),thickness of the left ventricular posterior wall(LVPWd),and left ventricular posterior wall(LVPWs).Cardiac output(CO)and blood pressure of rat tail artery were measured simultaneously.High performance liquid chromatography(HPLC)was used to detect NP content in heart tissue.HE staining,Sirius-Red staining and Masson trichrome staining were used to evaluate the histopathological changes in heart tissue,respectively.Inductively coupled plasma mass spectrometry(ICP-MS)was used to detect zinc and selenium concentration in heart tissue.Serum aspartate aminotransferase(AST),creatine kinase(CK),creatine kinase isoenzyme(CK-MB),lactate dehydrogenase(LDH)and a-hydroxybutyrate dehydrogenase(a-HBDH)was detected by automatic biochemical analyzer.The Image Pro-plus system was used to measure collagen volume fraction 1(CVF1)and collagen volume fraction 2(CVF2).Western blot was used to detect the expression levels of type I collagen(collagen(40))and type Ⅲ collagen(collagen Ⅲ).Real-time fluorescent quantitative PCR(RT-PCR)was used to detect the expression levels of collagen related genes(collagen(40),collagen Ⅲ).Results:1)The myocardial fibrosis induced by NP in rats.Compared with the control,the accumulation level of NP in heart of NP exposure group increased with an increase of exposure dose(F=13.704,P<0.01).Compared with the control,the LVAWs in NP exposure group was Thinner(FLVAWs=16.531,P<0.01),the LVIDd was increased(FLVIDd=9.873,P<0.01).Serum AST(FAST=43.388,P<0.01),CK(FCK=33.456,P<0.01),CK-MB(FCK-MB=13.929,P<0.01),LDH(FLDH=78.456,P<0.01),and a-HBDH(Fa-HBDH=26.237,P<0.01)in the NP exposure group increased significantly with an increase of exposure dose.Compared with the control,fibrous connective tissue was surrounded by blood vessels,the number of myocardial interstitial collagen increased,the arrangement of fibrous connective tissue disordered with lack of gridding shape,muscle fibers fractured with extensive inflammatory cell infiltration in the myocardial interstitium of the M-NP and H-NP groups.Red myocardial fibers in the NP groups were surrounded by blue-stained collagen fibers.The CVF1 between myocardium increased significantly with an increase of NP exposure dose(F=8.971,P<0.01).Yellow myocardial fibers were replaced by a large amount of red-stained collagen fibers,and the CVF2 between myocardium increased significantly with an increase of NP exposure dose(F=3.889,P<0.01).The expressions of collagen(40)(F collagen(40)=138.580,P<0.01)and collagen Ⅲ(F collagen Ⅲ=81.906,P<0.01)in heart tissue increased significantly in the NP groups,which increased with the increase of the exposure dose.The expressions of collagen I(F collagen(40)=138.580,P<0.01)and collagen II(F collagen Ⅲ=81.906,P<0.01)mRNA increased in the heart tissue of NP groups.2)The intervention effects of tea on NP-induced myocardial fibrosis in rats.Compared with the H-NP group,the LVAWs increased(F=21.200,P<0.01),while LVIDd decreased(F=16.531,P<0.01)in both zinc-selenium tea and green tea groups.The intervention effect of zinc-selenium tea was greater than that of green tea(P<0.01).Compared with the H-NP group,zinc-selenium tea and green tea intake could significantly decreased serum AST(FAST=37.535,P<0.01),CK(FCK=26.986,P<0.01),CK-MB(FCK-MB=14.066,P<0.01),LDH(FLDH=107.108,P<0.01),and a-HBDH(Fa-HBDH=28.077,P<0.01)levels,the degree of decrease was greater in zinc-selenium tea group compared to green tea group(P<0.01).Compared with the H-NP group,the disorder of myocardial fibrosis induced by NP was improved in the zinc-selenium tea and green tea groups.There was decreased inflammatory cell infiltration induced by NP in the Zinc-selenium tea and green tea groups.Zinc-selenium tea and green tea intake could significantly decrease CVF1(FCVF1=16.008,P<0.01)and CVF2(FCV2=54.458,P<0.01)between myocardium compared to H-NP,the degree of decreased CVF was greater in the zinc-selenium tea group than that of green tea(P<0.01).The expressions of collagen I(F collagen I=3.163,P<0.01)and collagen III(F collagen III =6.823,P<0.01)in myocardial tissue of rats significantly decreased in the Zinc-selenium tea and green tea groups compared to the H-NP group,and the protective effect was greater in zinc-selenium tea group than that of green tea group(P<0.01).Tea intake significantly reduced the expressions of collagen I(F collagen I =138.580,P<0.01)and collagen III(F collagen III,P<0.01)mRNA compared to the H-NP group.Conclusion:1)NP exposure could induce myocardial fibrosis and the damage of structure of heart in rats;moreover,NP increased the expression levels of myocardial enzymes(i.e.,collage I and collagen III)the sensitive indicators of the myocardial fibrosis induced by NP.2)Zinc-selenium tea intake could alleviate NP-induced cardiotoxicity,and its protective effects were greater than those of green tea. |
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