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BACKGROUND:Stem cell therapy is an alternative treatment strategy for restoring damaged myocardial tissue after acute myocardial infarction.Exercise preconditioning can induce endogenous cardioprotective effects in the body.However,the efficacy and mechanism of the combined application are still unclear. OBJECTIVE:To explore the effect and possible mechanism of exercise preconditioning combined with bone marrow mesenchymal stem cells on the therapeutic effect in rats with acute myocardial infarction. METHODS:Seventy male SD rats were randomly divided into sham operation group,model group,stem cell therapy group,exercise preconditioning group,and combined intervention group.Rats in the exercise preconditioning group and combined intervention group underwent 8-week aerobic exercise on the treadmill before modeling.The animal model of acute myocardial infarction was made by ligating the anterior descending coronary artery.The stem cell therapy group and the combined intervention group were injected with bone marrow mesenchymal stem cells(1×109 L-1,1 mL)through the tail vein the next day after modeling.After 4 weeks of treatment,the exercise performance was evaluated by a graded treadmill exercise test.The cardiac structure and function were detected by echocardiography.The left ventricle was isolated.2,3,5-Triphenyltetrazolium chloride staining was used to evaluate myocardial infarct size.Masson staining was used to obtain collagen volume fraction.CD31 immunohistochemical staining was used to detect myocardial capillary density.TUNEL staining was used to detect myocardial cell apoptosis.Immunoblotting was used to detect protein expression levels of stromal cell-derived factor 1,CXC chemokine receptor protein 4,tumor necrosis factor-α,interleukin-10,and vascular endothelial growth factor. RESULTS AND CONCLUSION:(1)Intervention efficacy:Compared with the sham operation group,exercise performance,left ventricular ejection fraction,left ventricular fractional shortening,and CD31 positive cell rate decreased(P<0.05);myocardial infarct size,collagen volume fraction,and myocardial apoptotic rate increased(P<0.05)in the model group.Compared with the model group,exercise performance was not statistically significant(P>0.05)in the stem cell therapy group,and the exercise performance improved(P<0.05)in the exercise preconditioning and combined intervention groups;left ventricular ejection fraction,left ventricular fractional shortening,and CD31 positive cell rate increased(P<0.05),and the myocardial infarct size,collagen volume fraction,and cardiomyocyte apoptosis rate decreased(P<0.05)in the stem cell therapy,exercise preconditioning,and combined intervention groups.Compared with the stem cell therapy group,exercise performance,left ventricular ejection fraction,left ventricular shortening fraction,and CD31 positive cell rate increased(P<0.05),myocardial infarct size,collagen volume fraction,and myocardial cell apoptosis rate decreased(P<0.05)in the combined intervention group.(2)Protein expression:Compared with the sham operation group,the expression of tumor necrosis factor-α increased(P<0.05),while interleukin-10 and vascular endothelial growth factor expression decreased(P<0.05)in the model group.Compared with the model group,the expression of CXC chemokine receptor protein 4 increased(P<0.05)in the stem cell therapy group and combined intervention group,and the expression of tumor necrosis factor-α decreased(P<0.05)while interleukin-10 and vascular endothelial growth factor increased(P<0.05)in the stem cell therapy group,exercise preconditioning group,and combined intervention group.Compared with the stem cell therapy group,the expression of tumor necrosis factor-α decreased(P<0.05),while CXC chemokine receptor protein 4,interleukin-10,and vascular endothelial growth factor increased(P<0.05)in the combined intervention group.To conclude,exercise preconditioning can enhance the therapeutic effect of bone marrow mesenchymal stem cells in rats with acute myocardial infarction,which can inhibit cardiac remodeling,improve cardiac function,and delay the progress of heart failure.Its mechanism is related to the promotion of stem cell homing,inhibition of inflammatory response,and promotion of angiogenesis.
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BACKGROUND:Exercise is an effective strategy to prevent and treat various cardiovascular diseases and protect the heart from ischemia-reperfusion injury.Its mechanism of action needs to be studied in depth. OBJECTIVE:To observe the effect of aerobic exercise preconditioning on myocardial ischemia-reperfusion injury and to explore the effect of endothelial nitric oxide synthase(eNOS)activation(including coupling and phosphorylation). METHODS:Eighty adult Wistar rats were randomly divided into sedentary(n=40)and exercise(n=40)groups.The rats in the exercise group were subjected to aerobic exercise for 8 weeks while those in the sedentary group were quietly fed and caged.After 8 weeks of intervention,three experiments were performed.(1)Experiment 1:After the last training,cardiac function,cardiac nitric oxide metabolite content and cardiac eNOS,phosphorylated eNOS-S1177,eNOS dimer and eNOS monomer protein expression levels were detected.(2)Experiment 2:Rats were divided into sedentary control group,exercise control group,sedentary+eNOS inhibitor group,exercise+eNOS inhibitor group,all of which were subjected to an in vitro myocardial ischemia-reperfusion injury experiment.eNOS inhibitor was continuously infused into the sedentary+eNOS inhibitor group and exercise+eNOS inhibitor group 10 minutes before reperfusion,and cardiac function and myocardial infarction area were detected 3 hours after reperfusion.(3)Experiment 3:Rats were divided into sedentary control group,exercise control group,sedentary+eNOS coupler group and exercise+eNOS coupler group,all of which were subjected to an in vitro myocardial ischemia-reperfusion injury experiment.The rats in the sedentary+eNOS coupler group and exercise+eNOS coupler group were treated with eNOS coupler.Myocardial infarct area,cardiac nitric oxide metabolite content,cardiac protein expression of eNOS,phosphorylated eNOS-S1177,eNOS dimer,eNOS monomer and 3-nitrotyrosine were detected 3 hours after reperfusion.The phosphorylated eNOS-S1177/eNOS ratio reflected the phosphorylated/dephosphorylated level of eNOS and eNOS dimer/monomer ratio reflected eNOS coupling/uncoupling level. RESULTS AND CONCLUSION:Experiment 1:Compared with the sedentary group,the exercise group had increased cardiac output and left ventricular ejection fraction(P<0.05),increased nitrite and S-nitrosothiol contents(P<0.05),upregulated phosphorylated eNOS-S1177,eNOS protein expression and phosphorylated eNOS-S1177/eNOS ratio(P<0.05),eNOS dimer protein expression and eNOS dimer/monomer ratios were elevated(P<0.05).Experiment 2:Compared with the sedentary control group,left ventricular development pressure increased(P<0.05)and myocardial infarct area decreased(P<0.05)in the exercise control group.Compared with the exercise control group,left ventricular development pressure decreased(P<0.05)and myocardial infarct area increased(P<0.05)in the exercise+eNOS inhibitor group.Experiment 3:Compared with the sedentary control group,the exercise control group had increased left ventricular developmental pressure(P<0.05),decreased myocardial infarct area(P<0.05),decreased phosphorylated eNOS-S1177/eNOS ratio(P<0.05),decreased eNOS dimer/monomer ratio(P<0.05),increased S-nitrosothiol content(P<0.05),and decreased 3-nitrotyrosine protein expression(P<0.05).Compared with the exercise control group,the exercise+eNOS coupler group had decreased left ventricular developmental pressure(P<0.05),increased myocardial infarct area(P<0.05),increased phosphorylated eNOS-S1177/eNOS ratio(P<0.05),increased eNOS dimer/monomer ratio(P<0.05),and elevated 3-nitro tyrosine protein expression(P<0.05).To conclude,aerobic exercise preconditioning could induce cardioprotection,which is related to uncoupling and dephosphorylation of eNOS during cardiac ischemia-reperfusion,thereby inhibiting the excessive production of nitric oxide and reducing nitro-oxidative stress.
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Objective:To explore the effects of different duration of exercise preconditioning on changes in cerebral blood flow and microglia activation related proteins in rats with vascular dementia. Method:Sixty SPF SD male rats were used to prepare vascular dementia rat models by permanent ligation of bilateral common carotid arteries.They were randomly divided into the model group,sham-operated group,ex-ercise preconditioning 4-week model group,exercise preconditioning 4-week sham-operated group,exercise pre-conditioning 2-week model group and exercise preconditioning 2-week sham-operated group,with 10 rats in each group.The exercise preconditioning 4-week rats received 30 minutes of moderate intensity non-weight-bear-ing swimming training 5 times a week for 4 weeks before modeling,while the exercise preconditioning 2-week rats received the same training for 2 weeks.Morris water maze was used to detect the spatial learning and memory ability of rats,laser speckle imaging technique was used to observe the changes of cerebral blood flow and the opening of collateral circulation of rats at different time point before and after the model-ing,and Western Blotting was used to detect the expression of TLR4 and Iba 1 protein in hippocampus. Result:Compared with the sham-operated group and the exercise preconditioning 2-week sham-operated group,the average escape latency time of rats in the exercise preconditioning 4-week sham-operated group,the model group,the exercise preconditioning 4-week model group and the exercise preconditioning 2-week model group was significantly prolonged(P＜0.05).Compared with the exercise preconditioning 4-week sham-operated group,the average escape latency time of rats in the model group and the exercise preconditioning 4-week model group was significantly prolonged(P＜0.05).Compared with the model group and exercise preconditioning 4-week model group,the average escape latency time of rats in exercise preconditioning 2-week model group was significantly decreased(P＜0.05).The simple effect of repetitive measurement deviation analysis suggested that the average cerebral blood flow before modeling,2h after modeling,3d after modeling and 7d after model-ing was statistically significant between the groups(P＜0.05).The simple effect of time factor on average cere-bral blood flow of the model group,the exercise preconditioning 4-week model group and the exercise precon-ditioning 2-week model group was statistically significant(P＜0.01).The opening of collateral circulation of rats in each group was observed.Compared with the model group,less reduction in microvessel diameter was ob-served in the exercise preconditioning 2-week model group(P＜0.05).Compared with the sham-operated group,the exercise preconditioning 4-week sham-operated group and the exercise preconditioning 2-week sham-operat-ed group,Ibal and TLR4 protein expressions in the model group were significantly increased(P＜0.01).Com-pared with the model group,Ibal and TLR4 protein expressions in the exercise preconditioning 2-week model group were decreased(P＜0.05). Conclusion:Moderate intensity exercise preconditioning for 2 weeks can improve the learning and memory abili-ty of vascular dementia rats,but exercise preconditioning for 4 weeks has no obvious effect on the improve-ment of learning and memory ability.The mechanism may be related to the improvement of cerebral blood flow status and the inhibition of microglia activation.
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Objective:To investigate the effect of exercise preconditioning on angiogenesis in ischemic brain tissue in rats with cerebral ischemia-reperfusion injury in the view of VEGF/VEGFR2/dock6 signaling pathway. Method:SD male rats were divided into sham group,model group and exercise preconditioning group by ran-dom number table method,with 18 rats in each group.The sham operation group and the model group were not given any treatment,while the exercise preconditioning group was given adaptive running training for 3 days at a speed of 10 m/min,once a day for 20 minutes each time.After the adaptive training,the exercise preconditioning group was given formal running training for 3 weeks,continuous training for 6 days a week,rest for 1 day,electric treadmill slope of 0°,speed of 15m/min,30min/d.Model group and exercise precondi-tioning group were modified to prepare the middle cerebal artery occlusion(MACO)models by Koizumi thread method,while sham operation group only given skin cutting without thread insertion.Zea longa score and modi-fied neurological severity score(mNSS)were used to score neurological deficit in rats,the relative infarct size of the brain was detected by TTC staining,the morphological changes of the ischemic cerebral cortex was ob-served by HE staining,the expression of CD31 in ischemic cerebral cortex was detected by immunohistochemis-try and the expressions of VEGFA,VEGFR2,Dock6 in ischemic cerebral cortex were detected by western blot. Result:①Zea-Longa scoring:after awaking from anesthetizati,compared with the sham group,the Zea-Longa scores of the other two groups were increased(P＜0.01),and there was no statistical significance in the Zea-Lon-ga scores between the two groups.At 72 hours after reperfusion,compared with the sham group,the Zea-Longa score of the rats in the model group was significantly increased(P＜0.01);compared with the model group,the Zea-Longa score of the rats in the exercise preconditioning group was significantly decreased(P＜0.05).②mNSS scoring:At 72 hours after reperfusion,compared with the sham group,the mNSS score of the rats in the mod-el group was significantly increased(P＜0.01);compared with the model group,the mNSS score of the rats in the exercise preconditioning group was significantly decreased(P＜0.05).③TTC staining:Compared with the sham group,the cerebral infarction volume in the model group was increased(P＜0.01),and compared with the mod-el group,the cerebral infarction volume in the exercise preconditioning group was decreased(P＜0.05).④ HE staining:Compared with the sham group,the model group rats appeared significant pathological changes in the cerebral cortex on the ischemic side.Compared with the model group,the pathological changes of the cerebral cortex on the ischemic side of the rats in the exercise preconditioning group were alleviated.⑤ Immunohisto-chemistry of CD31:Compared with the sham group,the expression of CD31 in the ischemic cerebral cortex of the model group was significantly increased(P＜0.05).The expression of CD31 in the ischemic cerebral cortex of the exercise preconditioning group was further increased(P＜0.05).⑥Western blot of VEGF,VEGFR2 and Dock6:Compared with the sham group,the expressions of VEGF(P＜0.05),VEGFR2(P＜0.05)and Dock6(P＜0.01)in the ischemic cerebral cortex of the model group were significantly increased;compared with the model group,the expressions of VEGF(P＜0.05),VEGFR2(P＜0.05)and Dock6(P＜0.01)in the ischemic cerebral cor-tex of the exercise preconditioning group were further increased. Conclusion:Exercise preconditioning can effectively promote angiogenesis after cerebral ischemia and reduce cerebral ischemia-reperfusion injury,which may be related to the activation of VEGF/VEGFR2/Dock6 signaling pathway.
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Objective:To observe any effect of exercise preconditioning on the levels of hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) in the brain tissue of rats after induced cerebral ischemia and reperfusion, and how it might promote angiogenesis.Methods:Thirty-six male Sprague-Dawley rats were randomly divided into a sham-operation group, a model group and an exercise preconditioning group, each of 12. After adaptive running training for 3 days, the exercise preconditioning group ran daily for 30 minutes at 15m/min for 14 days, while the other two groups did not exercise. Middle cerebral artery occlusion and reperfusion were then induced in the model and exercise preconditioning groups using the modified Zea-Longa suture method. Rats in the sham-operation group were only cut open to expose the right carotid artery. Right after the modeling, and again 24 hours later neurological deficit was evaluated using the Zea-Longa score and modified neurological severity scoring (mNSS). Infarct sizes were measured using 2, 3, 5-triphenyl tetrazolium chloride staining. Any morphological changes were noted using hematoxylin and eosin (HE) staining, and the expression of CD31 protein, hypoxia-inducible factor-1α and vascular endothelial growth factor in the ischemic cerebral cortex were quantified immunohistochemically.Results:Right after the modelling, compared with the sham-operation group, the average Zea-Longa scores of the model and exercise groups had increased significantly, but were not significantly different from each other. Twenty-four hours later the average Zea-Longa score, mNSS score and relative cerebral infarction area of the model group had increased significantly compared with the sham-operation group, while the exercise preconditioning group′s averages had decreased significantly. The HE staining showed that compared with the sham-operation group, pathological changes such as loose tissue, reduced number of nerve cells, nucleolysis, and vacuolization of the cerebral cortex on the ischemic side were found in the model group. Compared with the model group, the pathological changes in the exercise preconditioning group were less serious. The levels of CD31 protein, HIF-1α and VEGF in the ischemic cerebral cortexes of the model group had by then increased significantly. But compared with the model group, those levels had increased more in the exercise preconditioning group.Conclusion:Exercise preconditioning can effectively promote angiogenesis after cerebral ischemia and reduce chronic injury. That may be related to the activation of the HIF-1α and/or VEGF signaling pathways.
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Objective To explore the effect of exercise preconditioning on inflammatory response in ischemic stroke brain tissue which mediated by miR-146a in extracellular vesicles in rats with middle cerebral artery oc-clusion(MCAO),and its mechanism.Methods Sixty 6-week-old male Sprague-Dawley rats were randomly divid-ed into a non-exercise group and an exercise group.The non-exercise group was further divided into a sham-operation control group(C,n=15)and an MCAO model group(M,n=15),while the exercise group was further di-vided into an exercise only group(E,n=15)and an exercise plus MCAO model group(EM,n=15).Rats in the E and EM groups underwent 8 weeks of treadmill exercise,6 days per week,30 minutes per day.Then rats in the M and EM groups received MCAO to induce ischemic stroke,while the C and E groups underwent a sham surgery.Twenty-four hours after the surgery,neurobehavioral tests were performed.Plasma was collected to ex-tract extracellular vesicles,and brain tissue was collected to measure the volume of cerebral infarction by using the triphenyl tetrazolium chloride(TTC)staining.Moreover,the Nissl staining was conducted to observe neuronal and Nissl body.Mean while,the content of miR-146a in plasma extracellular vesicles and brain tissue was mea-sured by using the quantitative polymerase chain reaction(qPCR),and the expression of TNF receptor associat-ed factor 6(TRAF6),nuclear factor kappa-B(NF-κB)and tumor necrosis factor-α(TNF-α)in brain tissues were determined using Western blotting.The targeting relationship between miR-146a and TRAF6 was detected by using the dual luciferase reporter gene assay.Results(1)The neurological behavioral scores of the EM and M groups were higher than those of the C group(P<0.01 and P<0.01),with that of the EM group lower than the M group(P<0.01).(2)TTC staining showed that the infarct volume of the EM and M groups was larger than that of the other two groups(P<0.01 and P<0.01),with that of the EM group smaller than the M group(P<0.01).(3)Nissl staining results showed that the neuronal arrangement was loose,the number of neurons re-duced,and the Nissl bodies were lightly stained and decreased in the M group compared with the C and E groups.Moreover,compared with the M group,the number of neurons and Nissl bodies increased in the EM group.(4)The qPCR analysis showed that the expression of miR-146a in the plasma-derived exosomes and brain tissues of the EM and M groups decreased compared with the C group(P<0.05 and P<0.01),with that of the EM group higher than the M group(P<0.05).(5)According to Western blotting,compared with the C group,the expression levels of TRAF6,NF-κB,and TNF-α proteins increased significantly(P<0.05 and P<0.01),with that of group EM signfiicantly lower than group M(P<0.05 and P<0.05).(6)Dual-luciferase report-er gene assay showed that miR-146a had a specific binding site with TRAF6.Conclusion Eight weeks of exer-cise preconditioning reduces the infarct area and the extent of brain damage,which may be mediated by miR-146a via exosomes,increasing the expression of miR-146a in brain tissue,targeting TRAF6,negatively regulat-ing TRAF6/NF-κB,and reducing the expression of TNF-α,thus alleviating the inflammatory response in brain tissue and exerting a protective effect on ischemic brain injury.
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Objective:To study the effect of exercise preconditioning on the expression of autophagy-related protein Beclin 1 and microtubule-associated protein 1 light chain 3 (LC3), and apoptosis after myocardial ischemia-reperfusion injury in rats, to explore the mechanism of myocardial protection by exercise preconditioning. Methods:A total of 36 male Sprague-Dawley rats were randomly divided into sham operation group, model group and exercise preconditioning group, with twelve rats in each group. The exercise preconditioning group received electric treadmill training for four weeks before modeling. The model of myocardial ischemia-reperfusion was made by ligation of the left anterior descending coronary artery 30 minutes and reperfusion. One hour after reperfusion, the expression of Beclin 1 and LC3 protein in myocardium was detected by Western blotting, and apoptosis of myocardial cells was observed by TUNEL staining, then the apoptotic index was calculated. Results:Compared with the model group, the level of LC3-I protein in the myocardial ischemic area increased, the levels of Beclin 1 and LC3-II decreased, the ratio of LC3-II/LC3-I decreased (P < 0.05); and the apoptotic index decreased in the preconditioning group (P < 0.05). Conclusion:Exercise preconditioning could up-regulate LC3-I in ischemic area, down-regulate the expression of Beclin 1 and LC3-II, and inhibit cardiomyocyte apoptosis after ischemia-reperfusion.
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BACKGROUND; At present, the mechanism of exercise preconditioning for myocardial protection has not been fully elucidated. It is reported that Rho/ROCK pathway plays a key role in cardiovascular disease. Whether exercise preconditioning adapts to the myocardium through the Rho/ROCK signaling pathway remains to be studied. OBJECTIVE: To investigate the role of exercise preconditioning in rats with myocardial injury after exhaustive exercise. METHODS: Sixty male Sprague-Dawley rats of 5 weeks old were randomly divided into three groups: Control group, simple exhaustive exercise group (EE group), and exercise preconditioning group after exhaustive exercise (EP+EE group). At 1 hour after modeling, a serum sample from each rat was taken for biochemical analysis. The levels of aspartate aminotransferase, phosphocreatine kinase, and lactate dehydrogenase were detected. Myocardial tissue samples from each rat were taken for pathological observation using hematoxylin-alkaline reddish-picric acid staining. TUNEL method was used to observe apoptosis in the myocardial tissue. The levels of tumor necrosis factor-a and interleukin-10 in the myocardial tissue were detected by ELISA. The expression of RhoA, ROCK1, ROCK2, Bax, and Bcl-2 protein was analyzed by western blot. RESULTS AND CONCLUSION: The levels of aspartate aminotransferase, phosphocreatine kinase, and lactate dehydrogenase of the EE group were significantly higher than those of the control group (P < 0.05). The levels of aspartate aminotransferase, phosphocreatine kinase, and lactate dehydrogenase of the EP+EE group were significantly lower than those of the EE group (P < 0.05). The boundary of cardiomyocytes was unclear in the EE group, in which there were more plaque-like or flaky red-like areas as well as more obvious ischemia-anoxia changes as compared with the control group. Some cardiomyocytes presented with unclear boundary in the EP+EE group with some plaque-like brilliant red-like areas, and the degree of ischemia and anoxemia was significantly lower in the EP+EE group than the EE group. The apoptotic index value of the EE group was significantly higher than that of the control group, and the apoptotic index value of the EP+EE group was significantly lower than that of the EE group (P< 0.05). The tumor necrosis factor-a and interleukin-10 levels in the EE group were significantly higher than those in the control group (P < 0.05). The tumor necrosis factor-a and interleukin-10 levels in the EP+EE group were significantly lower than those in the EE group (P < 0.05). The Bcl-2/Bax of the EE group was significantly lower than that of the control group (P < 0.05). The Bcl-2/Bax of the EP+EE group was significantly higher than that of the EE group (P < 0.05). The levels of RhoA, ROCK1 and ROCK2 in the EE group were significantly higher than those in the control group. The levels of RhoA, ROCK1 and ROCK2 in the EP+EE group were significantly lower than those in the EE group (P < 0.05). These findings indicate that exercise preconditioning has a protective effect against myocardial injury and improves cardiac function in rats. The mechanism may be related to the Rho/ROCK pathway.
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Objective:To observe the effects of exercise preconditioning on blood-brain barrier (BBB) permeability, and connexin 43 (Cx43) and pannexin 1 (Panx1) protein after cerebral ischemia-reperfusion injury in rats. Methods:Fifty-four male Sprague-Dawley rats were randomly divided into sham group (n = 18), model group (n = 18) and exercise preconditioning group (n = 18). The exercise preconditioning group was trained with treadmill for three weeks before modeling. The middle cerebral arteries were occluded in the model group and the exercise preconditioning group using the modified Koizumi suture. After reperfusion of 24 hours, the rats were assessed with modified Neurological Severity Score (mNSS). The permeability of BBB was observed with Evans blue (EB). The expression of Cx43 and Panx1 was detected with Western blotting and immunohistochemistry in the ischemic tissues. Results:Compared with the model group, the mNSS score decreased in the exercise preconditioning group (P < 0.05), while the Evans blue content and the expression of Cx43 and Panx1 decreased (P < 0.05), as well as the the positive areas of Cx43 and Panx1 (P < 0.05). Conclusion:Exercise preconditioning can improve the permeability of BBB in cerebral ischemia-reperfusion rats, which may associate with down-regulation of Cx43 and Panx1, to protect brain from injury.
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Objective To observe the heart protective effect of exercise preconditioning (EP) in the acute exhaustion exercise (EE) rats, and explore its action mechanism further. Methods Eighty healthy male Sprague-Dawley (SD) rats were divided into control group (C group), EP group, EE group, and EP+EE group randomly, with 20 rats in each group. The rats in EP and EP+EE groups were trained for 3 weeks according to the daily swimming for 60 minutes (swimming 15 minutes, resting 5 minutes, repeating 3 times) with 6 days each week. The rats in EE and EP+EE groups on the last 1 day after 3 weeks, 3% weight heavy weight was carried once for swimming EE. Two hours after the last EE, abdominal aortic blood and heart was harvested, the levels of serum MB isoenzyme of creatine kinase (CK-MB) and calcitonin gene related peptide (CGRP) were determined by enzyme linked immunosorbent assay (ELISA); the ultrastructure of myocardium was observed by optical microscopy; the levels of myocardial malondialdehyde (MDA) and superoxide dismutase (SOD) were determined by ELISA, the mRNA expression of myocardial CGRP was assayed by reverse transcription-polymerase chain reaction (RT-PCR), and the protein expression of myocardial CGRP was assayed by Western Blot. Results Compared with C group, the levels of serum CK-MB and myocardial MDA were significantly increased, serum CGRP content, myocardial SOD activity, and mRNA and protein expressions of myocardial CGRP were significantly decreased in EE group and EP+EE group. Compared with EE group, the levels of serum CK-MB and myocardial MDA in EP+EE group were decreased [CK-MB (U/L): 13.11±0.77 vs. 15.55±0.90, MDA (μmol/L): 389.57±49.60 vs. 709.08±160.49], the level of serum CGRP, and mRNA and protein expressions of myocardium CGRP were increased [serum CGRP (ng/L): 120.41±9.07 vs. 97.97±9.05, CGRP mRNA (2 -ΔΔCT): 0.45±0.09 vs. 0.14±0.02, CGRP protein (gray value): 0.78±0.08 vs. 0.41±0.04, all P < 0.05], the degree of myocardial injury was obviously alleviated. There was no significant difference in the indexes between the EP group and C group. Conclusion EP has the heart protective effect for the acute EE rats, and the mechanism is closely related to the endogenous protective substance CGRP.
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@#Objective To explore the effect and mechanism of exercise preconditioning on neurological deficits in rats after cerebral ischemia-reperfusion. Methods Thirty-six healthy Sprague-Dawley rats were randomly divided into sham group (n=12), model group (n=12) and exercise preconditioning group (n=12). The latter two groups were occluded middle cerebral artery for 120 minutes and reperfused with modified suture method. The rats were evaluated with Longa's score two, twelve and 24 hours after reperfusion. The expression of mitochondrial ATP-sensitive potassium (mitoKATP) channel proteins inwardly rectifying potassium channel (Kir6.2) and sulphonylurea receptor 1 (SUR1) were detected with Western blotting and the cerebral cell apoptosis was detected with TUENL assay 24 hours after reperfusion. Results Compared with the model group, the Longa's score decreased in the exercise preconditioning group 24 hours after reperfusion (P<0.05), while the expression of Kir6.2 and SUR1 decreased (P<0.05), and TUNEL-positive cells decreased (P<0.05).Conclusion Exercise preconditioning may improve neurological function after cerebral ischemia-reperfusion, which may associate with inhibiting the expression of mitoKATP channel proteins and cell apoptosis.
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Objective To compare the expression of myocardial connexin 43(Cx43)mRNA and its protein during early and late cardioprotection stages of exercise preconditioning.Methods Thirty-two Sprague-Dawley rats were randomly divided into a control group,an exhaustive exercise(EE)group,an early exercise preconditioning + exhaustive exercise(EEP+EE)group and a late exercise preconditioning + exhaustive exercise (LEP+EE) group,each of 8.All groups were given intervention as their group name indicated.Then in situ hybridization and real-time fluorescent quantitative PCR methods were used to detect the changes of myocardial Cx43mRNA and immunohistochemical method and Western blotting were used to detect the changes of Cx43 protein.Results Compared with EE group,there was significant increase in Cx43 mRNA and its protein expression in group EEP+EE and LEP+EE.Compared with EEP+EE group,no significant changes was found in situ hybridization and Cx43 Immunoreactivity in LEP+EE group,neither did significant differences in the expression of Cx43 mRNA and its protein.Conclusion EEP and LEP can significantly promote the expression of myocardial Cx43 mRNA and its protein respectively.However there is no significant changes of myocardial Cx43 mRNA and protein expression between the 2 time phases.It demonstrates that the expression of Cx43 in the early and late stage of myocardial protective effect was consistent with the changes of the early and late phase of the protective effect of EP.
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Objective To investigate the effect of exercise preconditioning on the expression of nerve growth factor(NGF) and its receptor TrkA as well as learning-and-memory abilities in rats suffered from focal cerebral ischemia.Methods Thirty-six male SD rats were randomly divided into sham operation group (Sham-MCAO,n=12),focal cerebral ischemia-reperfusion group (MCAO,n=12) and exercise preconditioning + cerebral ischemia-reperfusion group (EX+MCAO,n=12).Rats in EX+MCAO group were placed in the treadmill device and accepted 4 weeks exercise training.Then method of middle cerebral artery occlusion was applied to prepare transient focal cerebral ischemia reperfusion model.Garcia's method was used to assess the neural function in rats.Western blotting was applied to test the expression of NGF and TrkA protein in the successfully established experimental MCAO rats.Morris water maze experiment was uti lized to test the learning-and-memory abilities of the rats.Results (1) Compared with Sham-MCAO group,the expression of NGF in rats' brain tissue was lower in MCAO group (cerebral ischemia 1h reperfusion 24h) (P＜0.05).The expression of NGF of EX+MCAO group was higher than that of MCAO group,but still lower than that of Sham-MCAO group (P＜0.05).(2)The expression of TrkA in rats' brain tissue was higher in MCAO group compared with Sham-MCAO group (P＜0.05).Compared with MCAO group,the expression of TrkA was even higher in EX+MCAO group (P＜0.05).(3)On the fifth day in the Morris water maze test,the latency of MCAO group was significantly longer than that of Sham-MCAO group((9.36± 1.18)s vs (4.86± 1.52) s,P＜0.05).However,compared with MCAO group,the latency in EX+MCAO group ((6.02± 1.04) s) was shorter,but still longer than Sham-MCAO group (P＜0.05).There was no significant difference among the three groups in the average swimming speed (P＞0.05).Conclusion Exercise preconditioning can up-regulate the expressions of NGF and TrkA protein,which can also improve the learning-and-memory abilities in rats suffered from focal cerebral ischemia reperfusion injury.
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@#Objective To explore the effect of exercise preconditioning on apoptosis and expression of P53 protein in ischemic penum-bra in rats after cerebral ischemia-reperfusion. Methods Thirty-six Sprague-Dawley rats were randomly divided into sham group, model group and exercise preconditioning group, with twelve rats in each group. The middle cerebral artery occlusion (MCAO) model was estab-lished with modified Longa's method. TUNEL method was used to observe the apoptosis of neural cells in the ischemic penumbra. Western blotting was used to detect the expression of P53 protein in the ischemic penumbra. Results Twenty-four hours after cerebral ischemia-reper-fusion, the number of TUNEL positive cells was more in the model group than in the sham group (P<0.01), and was less in the exercise pre-conditioning group than in the model group (P<0.01). The expression of P53 protein was higher in the model group than in the sham group (P<0.01), and was lower in the exercise preconditioning group than in the model group (P<0.01). Conclusion Exercise preconditioning coud down-regulate the expression of P53 protein in the ischemic penumbra, and inhibit the apoptosis of cortical cells.
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Objective To discuss the mechanism about exercise preconditioning (EP) protected myocardium by means of regulate NLRP3 inflammasome signal pathways on exhausted exercise rats. Methods The male Sprague-Dawley (SD) rats were randomly divided into four groups: normal control group (C group), no EP on exhausted exercise group (EE group), 3dEP + EE group, and 3wEP + EE group, with 12 rats in each group. In C group and EE group, the rats had not done exercise, while EE group took an exhausted swimming exercise with 3% heavy weight on tail at the end of 3 weeks; 3dEP + EE group and 3wEP + EE group exercised according to the standard of swimming for 60 minutes every day (swam 15 minutes, took a rest for 5 minutes, repeated 3 times), 6 days in a week, and were trained for 3 days and 3 weeks respectively, and took an exhausted swimming exercise on the last day. A light microscope and electron microscope were used to observe the myocardial histopathology and ultrastructure change, and enzyme linked immunosorbent assay (ELISA) was used to detect the levels of serum interleukin (IL-1β, IL-18, IL-6), hypersensitive C-reactive protein (hs-CRP), MB isoenzyme of creatine kinase (CK-MB), and brain natriuretic peptide (BNP). The protein expressions of NLRP3 and caspase-1 were detected by Western Blot. The correlations among all the parameters were analyzed by Pearson correlation analysis. Results Under the light microscope and electron microscope, the myocardial fiber morphological structure was normal, neatly, and no interstitial edema, muscle membrane damage or myocardial cell swellen was found in C group. In EE group, heart tissues were stained obviously uneven, a large number of myocardial fibers were fractured and messed, interstitial fibers were hyperplasiaed and edema moderately, much of myocardial cells were edema and necrosis, inflammatory cells were infiltrated, the number of average infiltration inflammatory cells was highest, mitochondria were edema seriously, part of the crest and a small number of membrane were blended together, fuzzy and crest were fractured, sarcomere were disordered; 3dEP + EE group and 3wEP + EE group heart tissues injuries were obviously alleviated, among the three groups, and the best results were in 3wEP + EE group. Compared with C group, the serum contents of IL-1β, IL-18, IL-6, hs-CRP, CK-MB, BNP and heart tissues protein expressions of NLRP3 and caspase-1 in EE group were significantly increased [IL-1β (μg/L): 18.77±1.28 vs. 12.00±1.55, IL-18 (μg/L): 236.79±15.73 vs. 150.74±7.09, IL-6 (μg/L): 59.31±9.17 vs. 34.65±2.89, hs-CRP (mg/L): 469.37±137.73 vs. 107.15±14.22, CK-MB (U/L): 15.57±0.91 vs. 7.40±0.40, BNP (ng/L): 532.08±63.44 vs. 386.96±34.77, NLRP3 protein (gray value): 0.66±0.07 vs. 0.16±0.06, caspase-1 protein (gray value): 0.96±0.08 vs. 0.48±0.06, all P 0.05]. A positive correlation was shown among IL-1β, IL-18, IL-6, hs-CRP, BNP, CK-MB, NLRP3, and caspase-1 (all P < 0.01). Conclusions EP can reduce inflammatory reaction by regulating the NLRP3 inflammatory signal pathways, and protect the myocardial injury. The protection of the heart by long-term EP is more obvious than that of short-term EP.
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Objective: To investigate the expression of myocardium connexin 43 (Cx43) in late exercise preconditioning (LEP) cardioprotection. Methods: Eight-week-old adult male Sprague Dawley rats were randomly assigned into four groups (n = 8). Myocardial injury was judged in accordance with serum levels of cTn[U+2160] and NT-proBNP as well as hematoxylin basicfuchsin picric acid staining of myocardium. Cx43 mRNA was detected by in situ hybridization and qualified by real-time fluorescence quantitative PCR. Cx43 protein was localized by immunohistochemistry and its expression level was determined by western blotting. Results: The LEP obviously attenuated the myocardial ischemia/hypoxia injury caused by exhaustive exercise. There was no significant difference of Cx43 mRNA level between the four groups. Cx43 protein level was decreased significantly in group EE (P < 0.05). However, LEP produced a significant increase in Cx43 protein level (P < 0.05), and the decreased Cx43 protein level in exhaustive exercise was significantly up-regulated by LEP (P < 0.05). Conclusions: LEP protects rat heart against exhaustive exercise-induced myocardial injury by up-regulating the expression of myocardial Cx43.
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Objective:To investigate the expression of myocardium connexin 43 (Cx43) in late exercise preconditioning (LEP) cardioprotection.Methods: Eight-week-old adult male Sprague Dawley rats were randomly assigned into four groups (n=8). Myocardial injury was judged in accordance with serum levels of cTnⅠ and NT-proBNP as well as hematoxylin basicfuchsin picric acid staining of myocardium.Cx43mRNA was detected byin situhybridization and qualified by real-time fluorescence quantitative PCR. Cx43 protein was localized by immunohistochemistry and its expression level was determined by western blotting.Results:The LEP obviously attenuated the myocardial ischemia/hypoxia injury caused by exhaustive exercise. There was no significant difference of Cx43mRNA level between the four groups. Cx43 protein level was decreased significantly in group EE (P<0.05). However, LEP produced a significant increase in Cx43 protein level (P<0.05), and the decreased Cx43 protein level in exhaustive exercise was significantly up-regulated by LEP (P<0.05).Conclusions:LEP protects rat heart against exhaustive exercise-induced myocardial injury by up-regulating the expression of myocardial Cx43.
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@#Objective To investigate the effect of exercise preconditioning on serum level of tumor necrosis factor α (TNF-α), interleukin (IL) -1β and IL-6 in rats after cerebral ischemia-reperfusion (I/R). Methods 24 male Sprague-Dawley rats were randomly divided into exercise preconditioning group (n=8), model group (n=8) and sham group (n=8). The middle cerebral arteries were occluded for 120 min and re-perfused. All the rats were evaluated with neurological deficit score 2 hours, 24 hours after I/R. The serum levels of TNF-α, IL-1β and IL-6 was detected with enzyme-linked immunosorbent, and the pathology was observed with HE staining 24 hours after I/R. Results The neurological deficit score decreased in the exercise preconditioning group compared with that in the model group, as well as the serum TNF-α, IL-1β and IL-6 (P<0.05) 24 hours after I/R. The pathological damage and interstitial edema alleviated in cerebral ischemia cortical, and the degeneration and necrosis of the neurons in the ischemic area significantly reduced in the exercise preconditioning group. Conclusion Exercise preconditioning may inhibit inflammatory response in I/R rats to protect neurological function from impairment.
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OBJECTIVE@#To investigate the expression of myocardium connexin 43 (Cx43) in late exercise preconditioning (LEP) cardioprotection.@*METHODS@#Eight-week-old adult male Sprague Dawley rats were randomly assigned into four groups (n = 8). Myocardial injury was judged in accordance with serum levels of cTnⅠ and NT-proBNP as well as hematoxylin basicfuchsin picric acid staining of myocardium. Cx43 mRNA was detected by in situ hybridization and qualified by real-time fluorescence quantitative PCR. Cx43 protein was localized by immunohistochemistry and its expression level was determined by western blotting.@*RESULTS@#The LEP obviously attenuated the myocardial ischemia/hypoxia injury caused by exhaustive exercise. There was no significant difference of Cx43 mRNA level between the four groups. Cx43 protein level was decreased significantly in group EE (P < 0.05). However, LEP produced a significant increase in Cx43 protein level (P < 0.05), and the decreased Cx43 protein level in exhaustive exercise was significantly up-regulated by LEP (P < 0.05).@*CONCLUSIONS@#LEP protects rat heart against exhaustive exercise-induced myocardial injury by up-regulating the expression of myocardial Cx43.
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Objective To investigate the effect of exercise preconditioning on serum level of tumor necrosis factorα(TNF-α), interleu-kin (IL)-1βand IL-6 in rats after cerebral ischemia-reperfusion (I/R). Methods 24 male Sprague-Dawley rats were randomly divided into exercise preconditioning group (n=8), model group (n=8) and sham group (n=8). The middle cerebral arteries were occluded for 120 min and re-perfused. All the rats were evaluated with neurological deficit score 2 hours, 24 hours after I/R. The serum levels of TNF-α, IL-1βand IL-6 was detected with enzyme-linked immunosorbent, and the pathology was observed with HE staining 24 hours after I/R. Results The neurological deficit score decreased in the exercise preconditioning group compared with that in the model group, as well as the serum TNF-α, IL-1βand IL-6 (P<0.05) 24 hours after I/R. The pathological damage and interstitial edema alleviated in cerebral ischemia cortical, and the degeneration and necrosis of the neurons in the ischemic area significantly reduced in the exercise preconditioning group. Conclu-sion Exercise preconditioning may inhibit inflammatory response in I/R rats to protect neurological function from impairment.