Background The loss of cardiac myocytes is one of the mechanisms involved in acute myocardial infarction （AMI）-related heart failure. Autophagy is a common biological process in eukaryote cells. The relationship bet...Background The loss of cardiac myocytes is one of the mechanisms involved in acute myocardial infarction （AMI）-related heart failure. Autophagy is a common biological process in eukaryote cells. The relationship between cardiac myocyte loss and autophagy after AMI is still unclear. Carvedilol, a non-selective α1-and β-receptor blocker, also suppresses cardiac myocyte necrosis and apoptosis induced by ischemia. However, the association between the therapeutic effects of carvedilol and autophagy is still not well understood. The aim of the present study was to establish a rat model of AMI and observe changes in autophagy in different zones of the myocardium and the effects of carvedilol on autophagy in AMI rats. Methods The animals were randomly assigned to a sham group, an AMI group, a chloroquine intervention group and a carvedilol group. The AMI rat model was established by ligating the left anterior descending coronary artery. The hearts were harvested at 40 minutes, 2 hours, 24 hours and 2 weeks after ligation in the AMI group, at 40 minutes in the chloroquine intervention group and at 2 weeks in other groups. Presence of autophagic vacuoles （AV） in the myocytes was observed by electron microscopy. The expression of autophagy-, anti-apoptotic- and apoptotic-related proteins, MAPLC-3, Beclin-1, Bcl-xl and Bax, were detected by immunohistochemical staining and Western blotting. Results AVs were not observed in necrotic regions of the myocardium 40 minutes after ligation of the coronary artery. A large number of AVs were found in the region bordering the infarction. Compared with the infarction region and the normal region, the formation of AV was significantly increased in the region bordering the infarction （P 〈0.05）. The expression of autophagy- and anti-apoptotic-related proteins was significantly increased in the region bordering the infarction. Meanwhile, the expression of apoptotic-related proteins was significantly increased in the infarction region. In the chloroquine intervention group, a large number of initiated AVs （AVis） were found in the necrotic myocardial region. At 2 weeks after AMI, AVs were frequently observed in myocardial cells in the AMI group, the carvedilol group and the sham group, and the number of AVs was significantly increased in the carvedilol group compared with both the AMI group and the sham group （P 〈0.05）. The expression of autophagy- and anti-apoptotic-related proteins was significantly increased in the carvedilol group compared with that in the AMI group, and the positive expression located in the infarction region and the region bordering the infarction. Conclusions AMI induces the formation of AV in the myocardium. The expression of anti-apoptosis-related proteins increases in response to upregulation of autophagy. Carvedilol increases the formation of AVs and upregulates autophagy and anti-apoptosis of the cardiac myocytes after AMI.展开更多
Background Sepsis-induced myocardial injury （SIMI） is caused by a variety of mechanisms. The aim of the study is to investigate the effects of metalloproteinase-8 （MMP-8） on SIMI and its mechanisms in rats. Method...Background Sepsis-induced myocardial injury （SIMI） is caused by a variety of mechanisms. The aim of the study is to investigate the effects of metalloproteinase-8 （MMP-8） on SIMI and its mechanisms in rats. Methods Forty male Sprague Dawley rats were randomly divided into four groups： MMP-8 inhibitor （M81）, dexamethasone （DEX）, sepsis, and sham groups. The sepsis model was established by cecal ligation and puncture （CLP）. Rats in the M81 group immediately received an intraperitoneal injection of M81 （0.1 mg/kg） after CLP. Rats in the DEX group immediately received an intraperitoneal （IP） injection of DEX （2 mg/kg）. Rats in the sepsis and sham groups received intraperitoneal injections of normal saline. Rats were sacrificed 12 hours after CLP. Paraffin sections were stained with hematoxylin and eosin to observe the myocardium. The myocardial ultrastructure was observed with transmission electron microscopy. MMP-8, tumor necrosis factor-Q （TNF-a）, and interleukin-113 （IL-113） were detected by immunohistochemistry. The expression of MMP-8 was measured by Western blotting. TNF-a and IL-113 levels in serum and myocardial tissue were determined by enzyme-linked immunosorbent assay. Results Compared with the sham group, the myocardium in the sepsis group was seriously injured. MMP-8, TNF-α and IL-1β expression was higher in the sepsis group than in the sham group, Treatment with M81 or DEX, however, attenuated sepsis induced histopathological changes in the heart, and was associated with significant reductions in serum and myocardial levels of TNF-a and IL-113 （P 〈0.05）. M81 significantly inhibited MMP-8 expression in myocardial tissue （P 〈0.05）. In addition, treatment with DEX was not associated with a change in myocardial levels of MMP-8 （P 〉0.05）. Conclusion MMP-8 inhibitor attenuated myocardial injury in septic rats, which might be related to reduced expression of TNF-α and IL-1β.展开更多
文摘Background The loss of cardiac myocytes is one of the mechanisms involved in acute myocardial infarction （AMI）-related heart failure. Autophagy is a common biological process in eukaryote cells. The relationship between cardiac myocyte loss and autophagy after AMI is still unclear. Carvedilol, a non-selective α1-and β-receptor blocker, also suppresses cardiac myocyte necrosis and apoptosis induced by ischemia. However, the association between the therapeutic effects of carvedilol and autophagy is still not well understood. The aim of the present study was to establish a rat model of AMI and observe changes in autophagy in different zones of the myocardium and the effects of carvedilol on autophagy in AMI rats. Methods The animals were randomly assigned to a sham group, an AMI group, a chloroquine intervention group and a carvedilol group. The AMI rat model was established by ligating the left anterior descending coronary artery. The hearts were harvested at 40 minutes, 2 hours, 24 hours and 2 weeks after ligation in the AMI group, at 40 minutes in the chloroquine intervention group and at 2 weeks in other groups. Presence of autophagic vacuoles （AV） in the myocytes was observed by electron microscopy. The expression of autophagy-, anti-apoptotic- and apoptotic-related proteins, MAPLC-3, Beclin-1, Bcl-xl and Bax, were detected by immunohistochemical staining and Western blotting. Results AVs were not observed in necrotic regions of the myocardium 40 minutes after ligation of the coronary artery. A large number of AVs were found in the region bordering the infarction. Compared with the infarction region and the normal region, the formation of AV was significantly increased in the region bordering the infarction （P 〈0.05）. The expression of autophagy- and anti-apoptotic-related proteins was significantly increased in the region bordering the infarction. Meanwhile, the expression of apoptotic-related proteins was significantly increased in the infarction region. In the chloroquine intervention group, a large number of initiated AVs （AVis） were found in the necrotic myocardial region. At 2 weeks after AMI, AVs were frequently observed in myocardial cells in the AMI group, the carvedilol group and the sham group, and the number of AVs was significantly increased in the carvedilol group compared with both the AMI group and the sham group （P 〈0.05）. The expression of autophagy- and anti-apoptotic-related proteins was significantly increased in the carvedilol group compared with that in the AMI group, and the positive expression located in the infarction region and the region bordering the infarction. Conclusions AMI induces the formation of AV in the myocardium. The expression of anti-apoptosis-related proteins increases in response to upregulation of autophagy. Carvedilol increases the formation of AVs and upregulates autophagy and anti-apoptosis of the cardiac myocytes after AMI.
文摘Background Sepsis-induced myocardial injury （SIMI） is caused by a variety of mechanisms. The aim of the study is to investigate the effects of metalloproteinase-8 （MMP-8） on SIMI and its mechanisms in rats. Methods Forty male Sprague Dawley rats were randomly divided into four groups： MMP-8 inhibitor （M81）, dexamethasone （DEX）, sepsis, and sham groups. The sepsis model was established by cecal ligation and puncture （CLP）. Rats in the M81 group immediately received an intraperitoneal injection of M81 （0.1 mg/kg） after CLP. Rats in the DEX group immediately received an intraperitoneal （IP） injection of DEX （2 mg/kg）. Rats in the sepsis and sham groups received intraperitoneal injections of normal saline. Rats were sacrificed 12 hours after CLP. Paraffin sections were stained with hematoxylin and eosin to observe the myocardium. The myocardial ultrastructure was observed with transmission electron microscopy. MMP-8, tumor necrosis factor-Q （TNF-a）, and interleukin-113 （IL-113） were detected by immunohistochemistry. The expression of MMP-8 was measured by Western blotting. TNF-a and IL-113 levels in serum and myocardial tissue were determined by enzyme-linked immunosorbent assay. Results Compared with the sham group, the myocardium in the sepsis group was seriously injured. MMP-8, TNF-α and IL-1β expression was higher in the sepsis group than in the sham group, Treatment with M81 or DEX, however, attenuated sepsis induced histopathological changes in the heart, and was associated with significant reductions in serum and myocardial levels of TNF-a and IL-113 （P 〈0.05）. M81 significantly inhibited MMP-8 expression in myocardial tissue （P 〈0.05）. In addition, treatment with DEX was not associated with a change in myocardial levels of MMP-8 （P 〉0.05）. Conclusion MMP-8 inhibitor attenuated myocardial injury in septic rats, which might be related to reduced expression of TNF-α and IL-1β.
