Study On The Effect And Mechanism Of Styrax For Myocardial Ischemia Rats

Objective: This study discussed the cardioprotective effects and related mechanism of Styrax for myocardial ischemia,inorder to explain the scientific connotation “pungent-heart-inducing resuscitation” that Styrax has the effect of inducing resuscitation and restoring consciousness,and lay an experimental foundation for Styrax used in clinic by comparing the pharmacodynamical effects of 3 different dosages.Methods: MI models were established in rats by ligation of the left anterior descending coronary artery.Recording the awakening time and Anal temperature.Surveying the changes of electrocardiograph and hemodynamic by BL-420 S biosystem recorder.Infarct volume was detected by 2,3,5-triphenyltetrazolium chloride(TTC)staining,and pathological changes were observed microscopically in Hematoxylin-eosin(HE)stained sections.The apoptosis cariomyocytes were observed under optic microscope after TUNEL method treatment.Myocardial infarct serum markers,creatine kinase isoenzyme(CK-MB),lactate dehydrogenase(LDH),aspartate aminotransferase(AST),NO,were detected by colorimetry,microplate method,and nitrate reductase method,respectively.The level of phosphatidylinositide 3-kinases(PI3K),phosphoserine-protein kinase B(p-Akt)and protein kinase(T-Akt),were measured by immunohistochemical method.And last,the yocardial apoptotic index was observed by TUNEL staining.Results:(1)0.167g/kg dosage of styrax group can significantly reduce the temperature of model rats,but increase the temperature of healthy rats in 2th day(P<0.05).Styrax 0.167g/kg and 0.333g/kg group could significantly shorten the recovery time of anesthesia model rats(P<0.01 or P<0.05);Styrax 0.667g/kg group had no significant effect on both two indexes.(2)Styrax 0.167g/kg and 0.333g/kg group can significantly reduce the heart rate within 30 min after ischemia in rats.Styrax 0.333g/kg and 0.667g/kg group can accelerate the heart rate after ischemia(P<0.01 or P<0.05).3 doses of Styrax can inhibit the status of MI rats(P<0.01 or P<0.05): ST segment down,T wave low level,QRS interval prolongation,Q wave deepening,S wave deepening,and the efficacy is related to the mode of administration and the dose administered.(3)Styrax 0.167g/kg group can reduce left ventricular systolic pressure,left ventricular diastolic pressure,left ventricular end diastolic pressure and left ventricular mean pressure significantly(P<0.01 or P<0.05)in MI rats after 72 h ischemia,but Styrax was no significant effect on the maximal rise(decrease)rate of left ventricle in MI rats(P>0.05).(4)TTC staining showed that the obvious pale infarct area was observed below the ligation site,and the most obvious was at the ligation and apex(P<0.01).The 0.167g/kg group significantly reduced the myocardial infarction rate of the model rats(P<0.01).The results showed that the ischmia myocardial cell had obvious degeneration,necrosis and edema,however,Styrax could improve the pathological changes(P<0.01 or P<0.05).(5)In addition,styrax could reduce the levels of AST,CK-MB and LDH in serum of model rats remarkablly(P<0.05 or P<0.01),and had no significant effect on NO content(P>0.05).(6)Styrax also decreased the expression of PI3 K,p-Akt and Akt in myocardial tissue of MI rats(P<0.05 or P<0.01),but had no significant effect on the interconversion of p-Akt and Akt proteins(P>0.05).(7)Other than these,Styrax also coud inhibit the apoptosis of myocardial cell(P<0.05).Conclusions: Styrax can motivate the recovery of MI rats,improve the heart function,reduce the infarction rate and myocardial enzyme activity,reduce the damage and degeneration of cardiomyocytes,and thus exert its effect of “acrid,opening heart,refreshing and coming to sense”.However,the effect was correlated with dose negatively.In addition,Styrax may delay the apoptosis by regulating the upstream pathway of PI3K/Akt to achieve anti-ischemic effects indirectly.The results implied that different dosage Styrax had diverse anti-myocardial ischemic impact strength :0.167g/kg>0.333g/kg>0.667g/kg,which provided an experimental reference for clinical effective and rational use of Styrax.