Effect Of EPO Intervention On Liver Cirrhosis Induced Myocardial Injury In Rat Model

Objective: To observe the role of EPO intervention on liver cirrhosis inducedmyocardial injury and the change of myocardial TGF-β1in rat model, further toinvestigate the mechanisms of the protection of EPO. The rat liver cirrhosis model wasinduced by CCl4composite method, the changes of myocardial function and thehappening of myocardial fibrosis were observed, and the expression of myocardialTGF-β1was measured, and the likely relationship was analyzed. This study will offerthe experimental basis for clinical improvement and prevention of complications ofcirrhotic cardiomyopathy.Methods: Thirty-six adult male Sprague-Dawley rats were randomly divided into threegroups:（1）Normal control group (Normal group,n=10), the rats were fed with regularfood and administered normal saline through subcutaneous injection（;2）Liver cirrhosisgroup（LC group,n=13）, the rats induced to liver cirrhosis by composite factor of carbontetrachloride: those were fed with food which consisting of maize flour, cholesterol(0.5%w/w) and alcohol (30%) and were administered with carbon tetrachloride(0.5ml/100g) on the first day, then administered with40%carbon tetrachloride (dilutedby peanut oil,0.3ml/100g) subcutaneously every four days for eight weeks.（3）Livercirrhosis group and intervention of erythropoietin group (LC+EPO group,n=13),the ratsin this group were copied cirrhosis model by above-mentioned method and treatedintraperitoneally (ip) with EPO2000iu/kg body weight (BW) twice a week, from thefifth week to the end of the experiments. Rats were operated on the ninth week. All ratswere anesthetized by4%chloral hydrate (1ml/100g, ip), then parameters of leftventricular function were recorded by ventricular intubation: including left ventricular systolic pressure (LVSP), maximal rise/fall rate of left ventricular pressure (±dp/dtmax).The levels of lactate dehydrogenase (LDH) and creatine kinase-MB (CK-MB) in serumwere measured. The level of IL-6in serum was measured by ELISA. Then myocardialtissue was fixed by paraformaldehyde. Paraffin-embedded hearts were sectioned anddewaxed for hematoxylin-eosin (HE) and Masson’s trichrome stain to observe thechange of morphology and collagen formation of myocardial tissur in different group bylight microscopy. The changes of transforming growth factor-beta1（TGF-β1）,collagenⅠ（ColⅠ） at mRNA level in myocardium were detected by reversetranscription polymerase chain reaction (RT-PCR).Results:(1) Heart weight/body weight ratio: compared with normal group, the ratio of heartweight/body weight was increased obviously in liver cirrhosis and EPO interventiongroup (p<0.01); compared with liver cirrhosis group, the ratio was reduced in EPOintervention group (p<0.01).(2)The changes of ventricular hemodynamic parameters: compared with normalgroup, LVSP and±dp/dtmax were decreased significantly (p<0.01). Compared withliver cirrhosis group, the left ventricular systolic peak pressure, maximal rise rate of leftventricular pressure and maximal fall rate of left ventricular pressure were significantlypromoted in EPO intervention group (p<0.05~p<0.01).(3)The contents of LDH, CK-MB: the levels of LDH and CK-MB in liver cirrhosisgroup were obviously higher than in normal control group (p<0.01)，compared withliver cirrhosis group, the releases of LDH and CK-MB were reduced significantly inEPO intervention group (p<0.05)，but significantly higher than in normal control group(p<0.05).(4) The lever of IL-6: the level of IL-6in liver cirrhosis group was obviouslyhigher than in normal control group (p<0.01)，compared with liver cirrhosis group, thelever of IL-6was reduced significantly in EPO intervention group (p<0.01) (5)The changes of histopathological change：Using HE and Masson’s trichromestaining, the results displayed that in liver cirrhosis group，cardiac myoneme wasdisordered, atrophied and dissolved，cardiac collagen deposition was appeared while thecardiac myoneme was normal and it was less mesenchymal cells in control group; theseinjuries were improved markedly in EPO intervention group.(6) RT-PCR detection of TGF-β1, ColⅠat mRNA level: Compared with normalcontrol group, the levels of TGF-β1and ColⅠmRNA were reduced in liver cirrhosisgroup (p<0.01); compared with liver cirrhosis group, the level of TGF-β1mRNA andColⅠmRNA were increased in EPO intervention group (p<0.05).Conclusions: Liver Cirrhosis can cause the changes of myocardial structure andfunction in rat. It can accelerate myocardial interstitial fibrosis; EPO can protect themyocardial injury of liver cirrhosis rat through down-regulation of TGF-β1, and itsdownstream target ColⅠgene may be involved in the mechanism.