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Expressions of PAR and Cleavage of Poly (ADP Ribose) Polymerase-1P89in Cardiomyocytes of Rats with Acute Myocardial Infarction

Author: HuangJianYe
Tutor: CongBin
School: Hebei Medical University
Course: Forensic
Keywords: Forensic Pathology AMI PAR PARP-1fragment(P89) IHC Western Blot
CLC: D919
Type: Master's thesis
Year: 2014
Downloads: 1
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Abstract

Objective: The phenomenon of sudden death caused by acute myocardialinfarction (AMI) occurred frequently in recent years. Because of the transientacute myocardial ischemia，most patients die in6hours, or even within1hourafter their attack. The regular HE staining would present the morphologicvariations of light microscope after6hours of myocardial ischemia(wavinessof cardiac muscle fibers, inflammatory cell infiltration, myocardial cells’acidophilic increased).However, in the practice of forensic, sudden death ofAMI often occurred within6hours after ischemia myocardial. The routineexamination after death, in addition to visible coronary artery and its branchesin different degrees of atherosclerosis, the pathological changes caused byischemic injury is difficult to discover, which made the paragnosis of earlymyocardial infarction has become a big difficulty of the identification offorensic pathology. It has been demonstrated that AMI could induce a highlevel expression of PAR and PARP-1cleavage (P89) which existed in ratcardiomyocyte. However, P89is a simple and sensitive mark of earlyapoptosis. As a convenient and practical method, immunohistochemical（IHC）, which can detect the changes of proteins in the ischemic myocardialcells, could provide a qualitative technical support of the postmortemdiagnosis of acute myocardial infarction (AMI). Western Blot is anexperimental method for semi quantitative detection of protein expression. Inthis study, we adopted the expression of IHC and Western Blot to test theexpression on ischemia myocardium’s PAR and P89during different time ofearly acute myocardial ischemia in rats, which is in order to search a utility,sensitiveness immunohistochemical marker for assist postmortem diagnosis ofSCD. Methods:80SD rats weighting250~300g of either sex, were randomlydistributed into Ischemia group（GROUP A）and Sham group(GROUP S). Therat model of early aute myocardial ischemia was established by ligating theleft anterior descending branch of coronary artery. The ischemia group ratswere killed at0.5h, lh,2h,4h and6h after ligation. Sham group rats underwentthe same surgical protocol as the ischemia group except LAD ligation, andwere killed at0,5h, lh,2h,4hand6h after operation Then draw materials tomake paraffin sections, using HE staining method to observe pathologicalchanges of heart tissue in rats, and the expression of PAR and P89weredetected by IHC. At the same time, using Western Blot to determine thevolume changes of the expression of P89. The data were analyzed usingSPSS16.0statistical program. A level of P<0.05was considered as statisticalsignificance.Results:1HE stainingSham operation group’s myocardial tissue structure is clear with noobvious abnormal morphological changes. AMI had very mild cellularswelling and interstitial edema within2h. There were manipulus inflammatorycells in the matrix and cardiac wavy muscle fibers with no obvious necrosis ingroup4h. In the6h group, it happened to see cardiac muscle fibers crackingand myocardial contraction band’s fracture.2IHC staining2.1The change of the expression of PAR at different time points aftermyocardial ischemiaThe Sham group: PAR in myocardial cell nuclei showed a negativeexpression.The ischemia groups: there was positive expression of PARIschemic myocardial cell nuclei at0.5h after myocardial ischemia, distributedin the endocardium, accumulated to cardiac muscle fibers at2h, thenaccumulated to the full thickness of the wall at6h. and1hour later, theintensity of positive expression was reinforcing significantly along with ischemic time; After2hours of ischemia, PAR in myocardial cell nucleishowed strong positive expression, which had obvious difference compared tosham group’s.2.2The change of the expression of P89at different time points aftermyocardial ischemiaThe Sham group: P89in myocardial cell nuclei showed a negativeexpression.The ischemia groups:0.5hour later, there was weakly positive expressionof P89in myocardial cell nuclei after myocardial ischemia, distributed in theendocardium, then accumulated to the full thickness of the wall at6h.1hourlater, the intensity of expression was reinforcing significantly along withischemic time;4hours later,P89expressed a wide range of positive, which hadobvious difference compared to sham group’s.3Western Blot: P89in myocardial cell nuclei showed the intensity of positiveexpression were reinforcing significantly along with ischemic time.Conclusions: PAR and P89appeared positive expression after0.5h of AMI,both of them ranged from endocardium to cardiac muscle fibers, accumulatedto the full thickness of the wall at last. and the intensity of positive expressionwas increasing with ischemic time. These two kinds of substance havehigh sensitivity, which can be used as reference index of the postmortemdiagnosis of acute myocardial infarction in forensic practice.

Expressions of PAR and Cleavage of Poly (ADP Ribose) Polymerase-1P89in Cardiomyocytes of Rats with Acute Myocardial Infarction

Abstract

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