| BACKGROUNDMyocardial fibrosis is characteristic by myocardial fibroblast proliferation, excessive fibrous tissue accumulation,collagen contents or ratio alteration (principally collagenâ… andâ…¢) in heart tissue, which involved in the process of cardiovascular diseases,such as,hypertension and myocardial infarction. The incidence of myocardial fibrosis increases quickly due to aging and cardiovascular dangerous factors, which progressively develop and lead to decreased heart function even severe cardiovascular incidents, dysprognosis, low quality of life. Traditional Chinese drug cure myocardial fibrosis in long history. Hemorheologic agent have a certain therapeutic effect in myocardial construction and function, prolong patiental lifetime, raise quality of life and light adverse reaction. But Traditional Chinese drug improving heart function have a few shortage,such as, optional compound recipe, indefinite mechanism in myocardial fibrosis. Therefore, related components of medicinal herb with exact clinic effect were extracted from compound recipe to exploit furtherly anti-myocardial fibrosis new drugs,which provid ideas for connection of Chinese medical science and modern principle in inhibiting myocardial fibrosis. Ligustrazine,an component extracted from ligustici, was used to cure many diseases in cardiovascular system, immune system, alimentary system, respiratory system and so, and especially had positive effact in some cardiovascular disease.There were experiment in MF, mainly in cellular level, few research in vivo.Thus, we established MF rat with abdominal aorta banding to research mechanism of ligustrazine in the model and provid support for clinic curing.OBJECTIVETo investigate the effects mechanism of ligustrazine on the level of collagen secretion and renin angiotensin aldosterone system in myocardial fibrosis model rats, in order to provide academic foundation on resisting myocardial fibrosis by ligustrazine.METHODS71 healthy male SD rats were randomly divided, by SAS, into 4 groups:sham operation group, model group, captopril group, ligustrazine group. According to the method of Doering et al, We anesthetized with intraperitoneal injection by 3% Pentobarbital(40 mg/kg), fixed, routinely sterilized, unfolding abdominal cavity and resulted in abdominal aortic partly banding with silver clip(inner diameter 0.7 mm). The operation in captopril group and ligustrazine group were identical with model group; we only opened abdominal cavity and separated abdominal aortic without banding.4 weeks after operation, rats in sham operation group and model group: lavage with distilled water(1.5 ml/100g,qd); rats in captopril group:lavage with captopril suspension(100 mg/kg,qd); rats in ligustrazine group:lavage with ligustrazine parenteral solution(25 mg/kg,qd). Rats were continuously lavaged for 4weeks in every group and then were dissected. We got blood 2ml from abdominal aorta and complete heart.8 weeks after operation, left ventricle and interventricular septum separated after anesthetizing was weight by electronic balance as left ventricle weight. Left ventricular mass index (LVMI)= left ventricle weight (mg)/body weight (g). We observed alterations of myocardial fibrosis pathological index through left ventricle myocardium collagen staining,left ventricle myocardium ultrastructure and immunocytochemical stain of collagen typeâ… andâ…¢of left ventricle myocardium in groups; expressions of myocardial AT1 mRNA and AT1 receptors were measured; it was detected by radio immunity that plasma renin angiotensin aldosterone system such as angiotensinâ…¡and aldosterone. Tnen these indexes were compared in groups and analysied possible mechanism of ligustrazine on myocardial fibrosis. The data was analyzed by SAS and SPSS 13.0 statistic software.RESULTS1. left ventricular mass index (LVMI)After the rats in model group underwent surgery for 8 weeks, LVMI of model group was increased (P<0.001, vs sham group). Captopril and Ligustrazine group were significantly different from model group (P<0.001), and were roughly identical to sham group (P=0.332, P=0.053); Captopril and Ligustrazine had no statistical difference(P=0.318).2. Left ventricle myocardium collagen staining.Less red collegen existenced in interstitial substance while lots of collegen presented in model group. But there were a few of red collagen regional between cardiac muscle cells in ligustrazine group, the differences were significant, compared with the model group. There were little red collagen between cardiac muscle cells in captopil group, which were similar with the sham group.3. Alterations of left ventricle myocardium ultrastructureThe ultrastructures of the sham operation group of 8 weeks after surgery were normal. All the forms of nucleus, cytoplasm, mitochondrion, sarcoplasmic reticulum and myofibril were normal. After 8 weeks of the surgery, the ultrastructures of the model group were conspicuous:some phenotypes decreased and break of mitochondrial cristas, shallow of matrix density, dilataltion of sarcoplasmic reticulum, the break of myofibril and disordered arrangement;the border of nucleus was not regular and chromatin moved aside. The ultrastructures of captopil group were same to those of sham group. Both were normal. Alterations of ultrastructures of left ventricle myocardium in ligustrazine group were similar to those of sham group. Some phenotypes were decrease and break of mitochondrial cristas, shallow of matrix density, dilataltion of sarcoplasmic reticulum, the break of myofibril and disordered arrangement. 4. Immunocytochemical stain of collagen typeâ… andâ…¢of Left ventricle myocardium.Average oculus dehter of collagen typeâ… of model group was increased (P<0.001) compared with that of sham operation group. Average oculus dehter of collagen in captopril group and ligustrazine group were decreased compared with model group (P<0.001), and had no visible difference with sham group (P=0.533, P=0.184). Captopril and Ligustrazine had no statistical difference (P=0.475).Average oculus dehter of collagen typeâ…¢of model group was increased (P<0.001) compared with that of sham operation group. Average oculus dehter of collagen typeâ…¢in captopril group and ligustrazine group were decreased compared with model group (P<0.001), and had visible difference with sham group (P=0.007, P=0.001). Captopril and Ligustrazine had no statistical difference (P=0.173).5. plasm level of Angâ…¡Plasm level of Angâ…¡in model group was increased (P<0.001) compared with that in sham operation group. Plasm level of Angâ…¡in captopril group and ligustrazine group were decreased compared with model group (P<0.001), and had no obvious difference to sham group (P=0.563, P=0.636). There was no visible disparity between captopril group and ligustrazine group(P=0.915).6. plasm level of ALDPlasm level of ALD in model group was increased (P<0.001) compared with that in sham operation group. Plasm level of ALD in captopril group and ligustrazine group were decreased compared with model group (P<0.001), and had no obvious difference to sham group (P=0.900, P=0.559). There was no visible disparity between captopril group and ligustrazine group (P=0.646)7.AT1 mRNA expressions and AT1 receptors of myocardium.AT1 mRNA expressions of model group were significantly increased (P<0.001), compared with sham operation group. AT1 mRNA in captopril group and ligustrazine group were decreased compared with model group (P<0.001), and had no obvious difference to sham group (P=0.633, P=0.310). There was no visible disparity between captopril group and ligustrazine group (P=0.584)AT1 receptors expressions of model group were significantly increased (P<0.001), compared with sham operation group. AT1 receptors in captopril group and ligustrazine group were decreased compared with model group (P<0.001), and had no obvious difference to sham group (P=0.990, P=0.619). There was no visible disparity between captopril group and ligustrazine group (P=0.610)CONCLUSIONS1.The result show that LVMI with pressure-overload were significantly increased, and collegen in myocardial interstitial deposited obviously. We copy succeedly model rats with abdominal aortic banding.2.8 weeks after operation, plasm level of Angâ…¡and ALD were increased obviously in model group, whenever AT1 mRNA expressions and AT1 receptors of left ventricle myocardium detected by immunohistochemistry.3. Traditional Chinese drug monomer ligustrazine could reduce synthesis of collegen in abdominal aortic banding rats which might be related to lower plasm level of Angâ…¡and ALD, AT1 mRNA expressions and AT1 receptors synthesis.4. Ligustrazine can inhibit process of myocardial fibrosis in abdominal aortic banding rats, and have similar effect with captopril. |
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