The Effect And Mechanism Of Icarrin On Attenuating The Apoptosis Of Cardiomyocytes In Spontaneously Hypertensive Rats

Objective: to observe the intervention of icarrin(ICA)on cardiomyocytes apoptosis of spontaneously hypertensive rats(SHR),and to explore the effect of the related factors on the regulation of mitochondrial controlled apoptosis pathway and endoplasmic reticulum stress(ERS)controlled apoptosis pathway.Methods: 28-male-SHR(aged 14 weeks)were randomly divided into the SHR group(n=7),ICA 10 mg/kg dose group(n=7),ICA 20 mg/kg dose group(n=7),ICA40 mg/kg dose group(n=7);and WKY rats(aged 14 weeks)were randomly divided into WKY group(n=7)and ICA simple drug administration group(40 mg/kg,n=7).All the ICA groups and ICA simple drug administration group were intragastrically administrated once a day until the rats were 26 weeks old,and the WKY group and the SHR group were given the same amount of dd H2 O instead.The weight changes of the rats in each group were recorded every week;blood pressure change was detected in the rats with Scientific CODA Kent system;the left ventricular function of the rats was detected by VEVO2100 ultrasound.After 12 weeks,the rats were injected with2% pentobarbital sodium and intraperitoneal injection of 0.2 ml/100 g then took out the heart and separated the left ventricle,the left ventricular mass index was calculated.The pathological changes of heart were observed by H&E staining,Masson`s three color staining method was used to observe the left ventricular collagen deposition,the apoptosis of cadiomyocytes of the heart tissue were observed by TUNEL staining,the morphological changes of mitochondria in the left ventricular myocardium were observed with electron microscope.Lastly the m RNA level of p53、Bcl-2、Bok、Bax、ATF-6、CHOP、IRE-1α、BAP31、ASK-1、ATF-4 were detected by RT-q RCR;the protein content of p53、Bcl-2、Bok、Bax、cleaved caspase3、GRP78、p-PERK、ATF-6、ATF-4、CHOP、caspase12、c-Jun、ASK-1、JNK、DR5 were examined by Western Blot.Results: Compared with the WKY group,the BP,FS,LVI,LVEDP of SHRs in SHR group were significantly increased(P<0.05),the EF,SV were significantly decreased(P<0.05).The hypertrophy,stretch,apoptosis as well as the disordered and non-polar arrangement of cardiomyocytes were obvious,also myocardial interstitial collagen deposition was visible,as the mitochondria proliferated,swelled,vacuolization and medullary sheath-like degeneration,the myofilament dissolved,the Z lines broken with irregular pattern of transverse striation.The m RNA and protein level of p53,Bok,Bax,CHOP,BAP31,ASK-1,ATF-4,JNK and ASK-1 were increased(P < 0.05),Bcl-2 m RNA and protein levels decreased(P< 0.05),while ATF-6 and IRE-1 alpha m RNA levels did not change significantly,cleaved caspase3,GRP78,p-PERK,caspase12,c-Jun,ATF-6,and DR5 were significantly increased(P< 0.05).Compared with the SHR group,the BP,FS,LVI,LVEDP of SHRs in SHR group were significantly decreased(P<0.05),the EF,SV were significantly increased(P<0.05).the LVEDP of SHR in ICA low and high dose group were increased(P<0.05),the hypertrophy of cardiomyocytes mitigated,the apoptosis of cardiomyocytes reduced,and the myocardial cells arranged neatly and polarly.The collagen deposition in myocardium was decreased,and the morphology of mitochondria in myocardial cells was normal.The m RNA and protein level of p53,Bok,Bax,CHOP,BAP31,ATF-4were decreased(P< 0.05),Bcl-2 m RNA and protein levels increased(P< 0.05),while ATF-6 and IRE-1 alpha m RNA levels did not change significantly,cleaved caspase3,GRP78,p-PERK,ATF-6,caspase12,c-Jun,JNK,DR5 were significantly reduced(P<0.05).Conclusion: Male SHR rats aged 26 weeks had pathological ventricular remodeling and cadiomyocytes apoptosis was significantly increased;ICA can inhibit pathological ventricular remodeling and reduce cadiomyocytes apoptosis,and its mechanism may be related with inhibiting of mitochondrial controlled apoptosis pathway and regulating of ERS controlled apoptosis pathway.