Effect of intervention for mast cell function before reperfusion on intestinal ischemia-reperfusion-induced early liver injury in rats

AIM：To explore the effect of intervention for mast cell function before reperfusion on intestinal ischemia-reperfusion (IR)-induced early liver injury. METHODS：Adult SD rats (n=35) were randomized into 5 groups with 7 rats each: sham operation group (S group), IR group, cromolyn sodium treatment group (IR+C group, 25 mg/kg), ketotifen treatment group (IR+K group, 1 mg/kg), compound 48/80 treatment group (IR+CP group, 0.75 mg/kg). IR was induced by superior mesenteric artery occlusion for 75 min followed by 4 h of reperfusion. The agents were intravenously administered 5 min before reperfusion. The serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and histamine, and the liver levels of lactate dehydrogenase (LDH), tumor necrosis factor α (TNF-α), interleukin-8 (IL-8), malondialdehyde (MDA) and superoxide dismutase (SOD) were assessed. The liver histopathologic changes were also evaluated. RESULTS：IR resulted in severe liver injury as demonstrated by great increases in injury scores, concomitant significant increases in serum levels of AST, ALT and histamine, and liver levels of LDH, TNF-α, IL-8, and MDA, accompanied by reduced SOD activity (all P<0.05 vs S group). Treatment with cromolyn sodium or ketotifen markedly alleviated IR-mediated liver injury as confirmed by significant reduction of the above biomedical changes, whereas compound 48/80 further aggravated liver injury by dramatically enhancing the biomedical changes (all P<0.05 vs IR group). CONCLUSION：Inhibition of mast cell function before reperfusion may reduce early liver injury induced by intestinal ischemia reperfusion. Histamine, oxidative stress and inflammatory response may provide promising effects on it.     

Beclin-1 expression is upregulated by spermine in rat myocardial ische-mia-reperfusion injury

AIM: To observe the effects of spermine (SP) on myocardial ischemia-reperfusion (IR) injury in rats. METHODS: SD rats (weighing 220~250 g) were equally randomized to 3 groups:sham control group, in which the rats were only treated with thoracotomy; IR group, in which the rats were treated with ischemia for 30 min and reperfusion for 60 min; and IR+SP group, in which 0.5 mmol/L SP (2 mL/kg) was intravenously injected just 15 min before reperfusion. The morphological changes of myocardial tissues were assessed by HE staining. The levels of cardiac troponin I (cTnI) and creatine kinase isoenzyme MB (CK-MB) in plasma were determined. Myocardial infarct size and no-reflow range of the myocardium were measured by Evans blue and thioflavin S staining. Inflammatory responses in the myocardial tissues were detected by myeloperoxidase (MPO) assay. The autophagy function was detected by measuring the protein expression of beclin-1 by Western blot. RESULTS: The myocardial injury and inflammatory infiltration in IR+SP group were reduced under light microscope. Treatment with SP decreased the plasma levels of cTnI and CK-MB, and reduced the IR-induced infarct size and no-reflow range size of the left ventricle (P<0.05). Tissue MPO assay showed that myocardial inflammatory responses were attenuated in IR+SP group compared with IR group. Beclin-1 was upregulated in IR+SP group compared with IR group (P<0.05). CONCLUSION: Exogenous SP attenuates myocardial ischemia-reperfusion injury by upregulating the expression of beclin-1.     

Establishment and evaluation of rat heart ischemia-reperfusion injury model in vivo

AIM: To establish and evaluate a rat model of heart ischemia-reperfusion injury in vivo. METHODS: Seventy-two male Sprague-Dawley rats weighing(250±50)g were randomly divided into sham operation group(sham), ischemia-reperfusion group(I/R) and normal group. The animals were anesthetized and heparinized. Myocardial ischemia-reperfusion was induced by ligating the left anterior descending coronary artery with "U-shape tube" for 35 min followed by 120 min or 240 min reperfusion in vivo. The heart infarct size was measured by triphenyltetrazolium chloride(TTC) staining. The myocardial cell apoptotic index was determined by the method of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling(TUNEL). Immunohistochemical method was used to detect the expression of Bcl-2 and Bax in rat ischemia myocardium. The blood level of MB isoenzyme of creatine kinase(CK-MB),cardiac troponin I(cTnI),nitric oxide(NO),malondialdehyde(MDA), total superoxide dismutase(T-SOD)and glutathione peroxidase(GSH-Px) were detected after reperfusion for 2 h and 4 h. RESULTS: Compared with normal group and sham group, there were obvious changes of ST-T segment and Q wave in the electrocardiogram of I/R group. The blood level of CK-MB, cTnI, NO, MDA and GSH-Px in I/R group increased(P<0.05,P<0.01) after reperfusion for 2 h and 4 h, and the blood level of T-SOD in I/R group after reperfusion for 2 h and 4 h also increased(P<0.05). The heart infarct size in I/R group was the largest as compared to other groups. Among these groups, the apoptotic index of I/R group was the highest and the Bcl-2/Bax ratio in I/R group decreased(P<0.01).CONCLUSION: The rat model of heart ischemia-reperfusion injury in vivo can be successfully established with the "U-shape tube". There are obviously changes of heart infarct size, blood level of CK-MB, cTnI, NO, MDA, T-SOD and GSH-Px, myocardial apoptotic index and Bcl-2/Bax ratio between I/R rats and control animals.     

Effects of heptanol preconditioning on structure,function and Cx43 content of mitochondria in rabbit model of myocardial ischemia/reperfusion injury

AIM: To investigate the effects of heptanol preconditioning on the changes of structure, function and connexin 43 (Cx43) content in mitochondria in a rabbit model of myocardial isehemia-reperfusion (IR) injury. METHODS: In anesthetized open-chest rabbits, the left anterior descending artery (LAD) was occluded for 30 min and reperfused for 4 h. Sixty-four rabbits were randomly divided into 4 groups (n=16 in each group): sham operation group (sham group), ischemia-reperfusion group (IR group), ischemic preconditioning group (IP group) and heptanol preconditioning group (HT group). All rabbits in the 4 groups were killed 4 h after reperfusion. Myocardial infarct size was determined at the end of the experiment. Mitochondria was isolated by centrifugations. The ultrastructural changes of the mitochondria were observed under electronic microscope. The mitochondrial membrane potential, Ca2+ concentration, MDA content and SOD activity of myocardial mitochondria were also examined. The content of mitochondria Cx43 was detected by Western blotting. RESULTS: Compared to IR group, the myocardial infarct size was significantly reduced in IP (18.97%±2.80%) and HT (19.97%±3.80%) groups, the damage of mitoehondrial ultrastructure was milder (P<0.05), mitochondrial membrane potential was significantly higher and Ca2+ concentration was much lower (P<0.01) in IP group and HT group. No significant difference of MDA content and SOD activity in myocardial mitochondria between IR group and HT group was found. However, MDA content were much lower and SOD activity was significantly higher in IP group as compared to IR group (P<0.01). Compared to sham group, the mitochondria Cx43 expression was distinctly decreased compared to IR group (P<0.05) and no significant difference was found between IP group and HT group (P>0.05). CONCLUSION: Heptanol preconditioning protects myocardium from ischemia-reperfusion injury. The mechanism may be related to increasing in mitochondrial membrane potential, alleviating Ca2+ overload in myocardial mitochondria and attenuating the decrease in mitochondria Cx43 expression induced by isehemia-reperfusion.     

Effects of HES 130/0.4 on no-reflow after myocardial ischemia-reperfusion injury in rats

AIM: To observe the effects and mechanisms of hydroxyethylstarch(HES) 130/0.4 on no-reflow phenomenon after myocardial ischemia-reperfusion in rats. METHODS: SD rats were randomly divided into 4 groups:sham operation group, ischemia-reperfusion(IR, treated with normal saline) group, normal saline ischemia-reperfusion(NS-IR, treated with NS) group and HES ischemia-reperfusion(HES-IR, treated with HES) group. Myocardial infarct size and no-reflow range were determined by staining methods, and the activities of myocardial enzymes(CK-MB, cTnI and MPO) were measured. Meanwhile, cardiac microvascular endothelial cells of the rat were cultured and divided into 4 groups:control group, hypoxia/reoxygenation(H/R) group, NS-H/R group and HES-H/R group. Acute ischemia reperfusion models were simulated, and the concentration of calcium ions was measured. The relative cell activity was evaluated by CCK-8 assay, and the apoptotic rate was detected by flow cytometry. RESULTS: In HES-IR group, the myocardial infarct size, the no-reflow zone, CK-MB, cTnI and MPO activity were all significantly lower than those in IR group(P<0.05). In microvascular endothelial cells, the concentration of calcium ions and the apoptotic rate in HES-H/R group were significantly decreased, while the relative cell activity increased compared with H/R group(P<0.05). CONCLUSION: HES reduces no-reflow in acute myocardial ischemia-reperfusion. The mechanism may be involved in the inhibition of both the infiltration of neutrophils and the calcium overload of endothelial cells.     

Abietic acid alleviates AGEs-induced apoptosis and endoplasmic reticulum stress in cardiomyocytes via inducing autophagy

AIM: This study aims to explore the effect of abietic acid (AA) on advanced glycosylation end products (AGEs)-induced apoptosis and endoplasmic reticulum stress in H9c2 cardiomyocytes. METHODS: H9c2 cells were divided into 5 groups. The cells in control group were treated with saline for 24 h. The cells in AGEs treatment group were treated with AGEs (100 mg/L) for 24 h. The cells in AGEs+AA (10, 25 and 50 μmol/L) groups were simulta-neously treated with AGEs (100 mg/L) and AA (10, 25 and 50 μmol/L) for 24 h. The cell viability was measured by MTT assay. The protein levels of myoglobin (Mb), creatine kinase MB isoenzyme (CK-MB), cardiac troponin I (cTnI), C/EBP homologous protein (CHOP), cleaved caspase-12, GADD34, BiP, LC3, P62 and beclin 1 were determined by Western blot. The levels of lactate dehydrogenase (LDH) were measured by ELASA. The apoptosis was analyzed by flow cytometry. RESULTS: The low concentration (<50 μmol/L) of abietic acid had no obvious effect on the viability of H9c2 cells. The high concentration (>50 μmol/L) of abietic acid decreased the viability of H9c2 cells. The levels of Mb, CK-MB, cTnI and LDH in AGEs group were higher than those in control group (P<0.05). Compared with AGEs group, the levels of Mb, CK-MB, cTnI and LDH in AGEs+AA (10, 25 and 50 μmol/L) groups were obviously reduced (P<0.05). Abietic acid at concentrations of 10, 25 and 50 μmol/L inhibited AGEs-induced apoptosis, elevated the protein levels of CHOP and cleaved caspase-12, and attenuated expression of GADD34 and BiP (P<0.05). Moreover, abietic acid at concentrations of 10, 25 and 50 μmol/L suppressed AGEs-induced decreased ratio of LC3-Ⅱ/LC3-Ⅰ and expression of beclin 1, and enhanced the expression of P62 (P<0.05). 3-Methyladenine, an inhibitor of autophagy, reversed the effect of abietic acid on the protein levels of LC3, Mb, cleaved caspase-12 and BiP (P<0.05). CONCLUSION: Abietic acid alleviates AGEs-induced apoptosis and endoplasmic reticulum stress in H9c2 cardiomyocytes via inducing autophagy.     

Effects of simvastatin on expression of Bcl-2 and Bax in myocardium of rats with renal ischemia-reperfusion injury

AIM: To observe the effect of simvastatin on myocardial tissue after renal ischemia-reperfusion injury and its mechanism. METHODS: A rat model of renal ischemia-reperfusion injury was prepared by clamping the bilateral renal arteries for 45 min. The rats (n=36) were randomly divided into sham operation group, renal ischemia-reperfusion (I/R) group and simvastatin group with 12 rats in each group. The content of serum creatinine (SCr), blood urea nitrogen (BUN) and myocardial tissue malondialdehyde (MDA), the myocardial activity of lactate dehydrogenase (LDH), creatine kinase (CK) and superoxide dismutase (SOD), and the myocardial protein expression of Bcl-2 and Bax were detected. RESULTS: Compared with sham operation group, the content of SCr, BUN and myocardial MDA, and the myocardial activity of LDH and CK in I/R group were significantly increased (P<0.05), and the activity of SOD was significantly decreased (P<0.05). Compared with I/R group, the content of SCr, BUN and myocardial MDA, and the myocardial activity of LDH and CK in simvastatin group were significantly decreased (P<0.05), while SOD activity was enhanced (P<0.05). The protein expression of Bcl-2 and Bax in sham operation group was less than that in I/R group (P<0.05), and the protein level of Bax in simvastatin group was significantly lower than that in I/R group (P<0.05), while the protein level of Bcl-2 was increased (P<0.05). CONCLUSION: Simvastatin has a protective effect on the myocardium of the rats with renal ischemia-reperfusion injury, and the protective mechanism may be related to the elimination of free radicals by simvastatin, increase in the protein expression of Bcl-2 and decrease in the protein expression of Bax.     

Effect of insulin on early myocardial oxidative stress in severely burnt rats

AIM：To investigate the effect of insulin on early myocardial oxidative stress in severely burnt rats. METHODS：Twenty-four Sprague-Dawley rats were randomly divided into three groups (8 rats in each group): control group (sham scald group), scald injury group and scald injury + insulin group. The rats in the latter two groups were subject to third-degree burn with 30% total burn surface area (TBSA) on the back, and then received intraperitoneal injection of normal saline (40 mL/kg) immediately. The rats in scald injury + insulin group were subcutaneously injected with insulin (1 U/kg), while those in scald injury group received subcutaneous injection of the same volume of normal saline. All rats were sacrificed 24 h after scald, and blood samples from abdominal aorta and myocardial tissues were taken. Blood glucose (BG) content, blood lactate dehydrogenase (LDH) and creatine kinase (CK) activity, and myocardial oxidative and antioxidative indexes, including malondialdehyde (MDA), xanthine oxidase (XO), myeloperoxidase (MPO), superoxide dismutase (SOD), catalase (CAT) and glutathion peroxidase (GPx), were detected by spectrophotometry. RESULTS：(1) Compared with control group, BG levels in scald injury group and scald injury + insulin group were significantly elevated (P<0.05). But BG in scald injury + insulin group was significantly lower than that in scald injury group (P<0.05). (2) Compared with control group, the activity of LDH and CK in scald injury group was significantly increased (P<0.05), while that in scald injury + insulin group was significantly lower than that in scald injury group (P<0.05). (3) Compared with control group, the MDA content and the XOD and MPO activity in scald injury group were significantly increased (P<0.05), while the activity of SO, CAT and GPx was significantly decreased (P<0.05). Compared with scald injury group, the MDA content and the XO and MPO activity in scald injury + insulin group were significantly reduced (P<0.05), while the activity of SOD, CAT and GPx was significantly elevated (P<0.05). CONCLUSION：Insulin intervention attenuates early myocardial oxidative stress in burnt rats and decreases the rise in myocardial enzyme activity, thus exerting a cardioprotective effect.     

Protective effects of basic fibroblast growth factor (bFGF) against to myocardial ischemia in rats

AIM: To study the protective effects of basic fibroblast growth factor (bFGF) on myocardial ischemia in rats and their underlying mechanism. METHODS: A rat myocardial ischemic injury model was established by left coronary artery ligation. The rats were killed at 2 h, 4 h, 8 h after coronary artery occlusion. The samples of blood and myocardium were collected for observing the expression of Bcl-2 and Bax in myocardial cells and the changes of superoxide dismutase (SOD) or myocardial enzymes. RESULTS: The amount of Bcl-2 protein expression of myocardial cells in ischemia + bFGF group was significantly higher than that in ischemia+saline group (P＜0.01) at 2 h, 4 h after coronary artery occlusion. However, the change of Bax protein expression was reversed (P＜0.05). The activity of SOD in ischemia+bFGF group was higher than that in ischemia+saline group, and the changes of LDH, CK-MB and α-HBDH in ischemia+bFGF group were reversed (P＜0.05) in serum. CONCLUSION: bFGF has protective roles against myocardial ischemia in rats.     

Genipin inhibits oxidative stress and apoptotic damage in high glucose-induced H9c2 cardiomyocytes

AIM:To explore the effects of genipin (GEN) on high glucose (HG)-induced oxidative stress injury and apoptosis in H9c2 cardiomyocytes.METHODS:H9c2 cells were cultured in vitro and HG-induced injury model was established. H9c2 cells were divided into 4 groups:normal control (NC) group (glucose at 5.6 mmol/L), HG group (glucose at 50 mmol/L), NG+GEN group and HG+GEN group. The concentration of genipin was used at 10 μmol/L. The viability of the H9c2 cells was measured by CCK-8 assay. The intracellular malondialdehyde (MDA) content and superoxide dismutase (SOD) activity were determined by enzyme labeling and WST-1 methods, respectively. The activity of lactate dehydrogenase (LDH) in the cell culture supernatant was detected by microplate method. Fluorescent probe DCF was used to detect intracellular levels of reactive oxygen species (ROS). Nucleosome fragments was measured to evaluate cell apoptosis by ELISA. The intracellular mitochondrial membrane potential was detected by JC-1 method. The protein levels of Mn-SOD, cytochrome C (Cyt C), Bax and cleaved caspase-3 were determined by Western blot. RESULTS:Compared with HG group, the cell viability in HG+GEN group was increased significantly (P<0.05), the levels of MDA and LDH were decreased (P<0.05), SOD activity was increased (P<0.05), the levels of ROS and nucleosome fragments in HG+GEN group were decreased (P<0.05), and the mitochondrial membranes potential was notably increased (P<0.05). Compared with NG group, the activation of Mn-SOD was decreased, but the protein levels of Cyt C, Bax and cleaved caspase-3 were increased in HG group (P<0.05). Compared with HG group, the activation of Mn-SOD was increased, and the protein levels of Cyt C, Bax and cleaved caspase-3 were decreased in HG+GEN group (P<0.05).CONCLUSION:Genipin protects HG-induced H9c2 cardiomyocytes against oxidative stress injury and apoptosis.     

Inhibitory effect of ginkgo-dipyridamole injection on ischemia/reperfusion injury in rat hearts in vitro

AIM：To investigate the effect of ginkgo-dipyridamole injection (GD) on ischemia/reperfusion (I/R) injury in rat hearts in vitro and its possible mechanism. METHODS：Forty male Sprague-Dawley rats were randomly divided into 5 groups (n=8): normal control (NC) group, I/R group, ischemic preconditioning (IPC)+I/R group, GD+I/R group and GD+LaCl3+I/R group. Cardiac function indexes, including heart rate (HR), left ventricular systolic pressure (LVSP) and the maximal rise/fall rate of left ventricular pressure (±dp/dtmax), were detected at 5 time points, including stabilizing point, 30 min after ischemia, and 5, 30 and 60 min after reperfusion. The activity of lactate dehydrogenase (LDH) and creatine kinase (CK) in coronary effluent at the five time points was assayed. The concentration of Ca2+ and the content of α-ketoglutarate dehydrogenase (α-OGDH) in myocardial mitochondria were determined at the end of the whole experiment. RESULTS：Compared with I/R group, the cardiac function indexes in IPC+I/R and GD+I/R groups were improved at the reperfusion period (P<0.05), the activity of LDH and CK in coronary effluent and the concentration of Ca2+ in mitochondria were significant reduced (P<0.01), and the content of α-OGDH was increased (P<0.05). However, the protective effect of GD was inhibited by LaCl3 (P<0.05). CONCLUSION：GD protects rat hearts against I/R injury by inhibiting calcium overload and improving mitochondrial enzyme activity to stabilize mitochondrial energy metabolism.     

Cardiac protective effect of granulocyte colony-stimulating factor combined with ischemic postconditioning on acute myocardial infarction in rabbits

AIM: To investigate the protective effect of granulocyte colony-stimulating factor (G-CSF) combined with ischemic postconditioning (IP) on acute myocardial infarction (AMI). METHODS: Male New Zealand rabbits were randomly divided into 4 groups (n=15) after 30 min of left ventricular artery (LVA) occlusion: the rabbits in ischemia-reperfusion (IR) group were directly given reperfusion|the rabbits in G-CSF group were subsequently treated with G-CSF (10 μg·kg^-1·d^-1) by subcutaneous injection after direct reperfusion|the rabbits in IP group received 4 episodes of 30 s reperfusion and 30 s occlusion before total reperfusion|the rabbits in IP combined with G-CSF (IP+G-CSF) group were treated with both IP and G-CSF. Electrocardiogram (ECG) monitoring was performed during the operation. Blood was drawn to evaluate white blood cell count (WBC) and cardiac troponin I (cTnI) before operation and 7 d later. Ultrasound cardiography was performed to evaluate left ventricular remodeling and functions 4 weeks after operation. The sizes of infarcted myocardium were determined by triphenyltetrazolium chloride (TTC) staining. Apoptosis of cardiomyocytes was measured by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) staining. RESULTS: ST-segment resolutions were significantly decreased in IP group and IP+G-CSF group compared with direct reperfusion groups (P<0.05). WBC significantly increased in the groups treated with G-CSF for 1 week. The values of cTnI after operation were significantly lowered in G-CSF group, IP group and IP+G-CSF group as compared with IR group (P<0.05). Left ventricular ejection fraction, the size of infarcted myocardium and apoptosis of cardiomyocytes were better in IP group, G-CSF group and IP+G-CSF group than those in IR group. CONCLUSION: G-CSF combined with IP is a promising strategy against cardiac reperfusion injury and accelerates cardiac repair in AMI.     

Effects of glucagon-like peptide-1 on myocardial ischemia-reperfusion/hypoxia-reoxygenation injury in rats

AIM: To investigate the effects of glucagon-like peptide-1 (GLP-1) on myocardial ischemia-reperfusion (IR)/hypoxia-reoxygenation (HR) injury in rats. METHODS: Sprague-Dawley rats were randomly divided into 5 groups: sham group, IR group and IR+GLP-1 (0.03 nmol/L, 0.16 nmol/L and 0.30 nmol/L) groups. IR group and IR+GLP-1 group were subject to 30 min of ischemia and 3 h of reperfusion. The myocardial infarct size, the ultrastructural changes of the myocardial tissues, the apoptosis of the cardiomyocytes, the activity of superoxide dismutase (SOD) and the concentration of malondialdehyde (MDA) were detected. Primarily cultured cardiomyocytes were divided into 5 groups at random: control group, HR group and HR+GLP-1 (1 μmol/L, 5 μmol/L and 10 μmol/L) groups. The morphology and apoptosis of the cardiomyocytes were observed. The levels of lactate dehydrogenase (LDH),MDA,SOD,reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) in different groups were detected. RESULTS: Compared with IR group, the myocardial infarct size and cardiomyocyte apoptosis were remarkably reduced, mitochondrial ultrastructures were improved, the activity of SOD was increased and the concentration of MDA was decreased in IR+GLP-1 (0.03 nmol/L, 0.16 nmol/L and 0.30 nmol/L) groups. Compared with HR group, GLP-1 (1 μmol/L, 5 μmol/L and 10 μmol/L) preconditioning significantly decreased the myocardial injury, increased SOD activity, decreased MDA concentration and ROS production, and heightened MMP in a dose-dependent manner. CONCLUSION: GLP-1 protects cardiomyocytes from IR/HR injury, which may be partially due to the effects of anti-oxidative mechanism and the function of mitochondrial protection.     

Protective effect of ischemic-preconditioning under the mild hypothermia against small intestine ischemia-reperfusion injury in rats

AIM: To investigate the protective effect of ischemic-preconditioning under the mild hypothermia against small intestine ischemia-reperfusion injury in rats and its mechanism. METHODS: Thirty-two rats were randomized into 4 groups (8 rats in each group): sham operated group (Sham), ischemia-reperfusion (I/R) group, ischemic-preconditioning (IP) group, mild hypothermia ischemic-preconditioning (MHIP) group. The wet/dry ratio, Ca²⁺-Mg²⁺-ATPase activity in intestine tissue, the malondialdehyde (MDA) content, activities of lactate dehydrogenase (LDH), superoxide dismutase (SOD) and total antioxdase (TAX) in blood were determined. Ultrastructure, Bcl-2 and Bax expression in intestinal mucosa tissue were also observed. RESULTS: After I/R, the intestinal tissue wet/dry ratio, the content of MDA, LDH activity, the optic density of Bcl-2 and Bax proteins were significantly higher in I/R group than those in sham group (P<0.01). The activities of Ca²⁺-Mg²⁺-ATPase, SOD, TAX were significantly lower in I/R group than those in sham group (P<0.01). The intestinal tissue wet/dry ratio, the content of MDA, LDH activity and the optic density of Bax protein were significantly lower in IP group than those in I/R group (P<0.01), and also lower in MHIP group than in IP group (P<0.05). The activities of Ca²⁺-Mg²⁺-ATPase, SOD, TAX and the optic density of Bcl-2 protein were significantly higher in IP group than in I/R group (P<0.01). CONCLUSION: MHIP can protect intestine against I/R injury in rats, which may be related to enhancing oxidation-resistance of intestine, inhibiting lipid peroxidation, upregulating the expression of Bcl-2 protein and downregulating the expression of Bax protein.     

Role of HIF-1α/VEGF pathway in treatment of cerebral ischemia-reperfusion injury by hyperbaric oxygen pretreatment

AIM: To investigate the role of hypoxia-inducible factor-1α (HIF-1α)/vascular endothelial growth factor (VEGF) pathway in hyperbaric oxygen (HO) pretreatment in rats with cerebral ischemia-reperfusion (IR) injury. METHODS: Healthy male SD rats (n=32) were randomly divided into control group IR group, HO-IR group and HO-IR-HIF-1α inhibitor group (HO-IR-I group). The IR model was established by middle cerebral artery occlusion. The corresponding blood vessels of the rats in control group were only exposed. The rats in HO-IR group and HO-IR-I group were treated with HO for 4 weeks before the animal modeling. The rats in HO-IR-I group received 3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazol (YC-1) by intraperitoneal injection at 4 mg/kg before HO preconditioning every day. At 1 d and 7 d after modeling, the neurological assessment was evaluated.At the end of the 7 th day, after observation, the rats were sacrificed by anesthesia to measure the infarct volume of the brain tissue. The protein levels of HIF-1α, VEGF and apoptosis-related proteins Bax and Bcl-2 were determined by Western blot. The number of apoptotic cells was detected by TUNEL. RESULTS: Compared with control group, the neurological function score was decreased, while the cerebral infarction volume ratio, the protein levels of HIF-1α, VEGF, Bcl-2 and Bax, and the apoptotic cells were increased in IR group, HO-IR group and HO-IR-I group (P<0.05). Compared with IR group, the neurological function score, and the protein levels of HIF-1α,VEGF and Bcl-2 were increased, while the cerebral infarction volume ratio, the protein level of Bax and apoptotic cells were decreased in HO-IR group and HO-IR-I group (P<0.05). Compared with HO-IR group, the neurological function score, and the protein levels of HIF-1α, VEGF and Bcl-2 were decreased, while the cerebral infarction volume ratio, the protein level of Bax and apoptotic cells were increased in HO-IR-I group (P<0.05). CONCLUSION: The mechanism of HO preconditioning attenuating cerebral IR injury may be related to the regulation of apoptosis by inducing HIF-1α/VEGF signaling pathway activation.     

Effects of heat shock protein 70 on inflammation after hepatic local ischemia/reperfusion in rats

AIM:To study the effects of heat shock protein 70 (HSP70) induced by the heat stress pretreatment on inflammation after hepatic ischemia/resperfusion.METHODS:With the hepatic local ischemia/reperfusion model (IR group),heat stress pretreatment (H+IR group) and injecting quercetin before heat stress pretreatment (Q+H+IR group) were performed.The HSP70,intercellular adhesion molecule-1 (ICAM-1) and the myeloperoxidase (MPO) activity were detected.The levels of serum ALT and AST and histological changes of the hepatocytes were also observed.RESULTS:In H+IR group,the HSP70 expression was higher than that in other groups at each time point,after performing ischemia-perfusion,hepatic injury was slighter.The levels of serum ALT and AST were increased slightly (P<0.01).The expression of ICAM-1 and the changes of MPO activity increased and peaked respectively at 6 h and 12 h after reperfusion.However,they were lower in H+IR group than those in IR group and Q+H+IR group.CONCLUSION:The HSP70 induced by heat stress pretreament reduces the expression of ICAM-1 and the changes of MPO activity during hepatic ischemia-reperfusion,then hepatic injury is depressed from the inflammation.     

Role of GRP78 in alteration of myocardium induced by intestinal endotoxemia in cirrhotic rats

AIM: To explore the role of glucose-regulated protein 78 (GRP78) in the alteration of myocardium induced by intestinal endotoxemia in cirrhotic rats. METHODS: Fifty-one male Wistar rats were randomly divided into liver cirrhosis groups of 4-week, 6-week and 8-week, and normal control groups at corresponding time points. The cardiac functions of the 8-week rats were measured. Tumor necrosis factor α(TNF-α) and malondialdehyde(MDA) in myocardial tissues were detected. The number of myocardial cells and the collagen volume fraction (CVF) were determined with toluidine blue and van Giesan staining, respectively. The expression of GRP78 and hypoxia-inducible facotr 1α(HIF-1α) was analyzed by the method of immnunohistochemistry. RESULTS: Compared with normal control group at corresponding time point, left ventricular end-diastolic pressure(LVEDP) and ±LV dp/dt_max in 8-week group were significantly decreased (P<0.05). The levels of TNF-α, MDA and CVF, the protein expression of GRP78 and HIF-1α in the myocardial tissues were significantly increased in every model group (P<0.05), and the number of myocardial cells was gradually decreased (P<0.05). Elevated levels of endotoxin in plasma were positively correlated with the levels of alanine aminotransferase (ALT),homocysteine (Hcy) and TNF-α in plasma, the levels of TNF-α, MDA and CVF, and protein levels of GRP78 and HIF-1α in the myocardial tissues (P<0.05). Elevated protein expression of GRP78 in the myocardial tissues was positively correlated with the levels of ALT, Hcy in plasma and MDA, CVF, HIF-1α protein in the myocardial tissues (P<0.05). CONCLUSION: Intestinal endotoxemia induced by liver cirrhosis may directly or indirectly lead to endoplasmic reticulum stress and overexpression of GRP78. GRP78 may be a key molecule in the pathogenesis of myocardial remodeling and functional alteration induced by liver cirrhosis.     

Yiqi-Yangyin recipe attenuates myocardial ischemia-reperfusion injury in diabetic rats by activation of ERK/Nrf2/HO-1 pathway

AIM: To explore the effect of Yiqi-Yangyin recipe on myocardial ischemia-reperfusion injury (MIRI) in rats with diabetes mellitus (DM) and the possible mechanism. METHODS: The rats were divided into normal group (control group), DM sham operation (DM-S) group, DM+MIRI group, low-, medium-and high-dose Yiqi-Yang-yin recipe (TL, TM and TH) groups (7.5, 15 and 30 g/kg decoction of Yiqi-Yangyin recipe by gavage), and Nrf2 inhibitor (bardoxolone methyl) group (30 mg/kg bardoxolone methyl by intragastric administration). The gavage volume was 1 mL/kg. There were 15 rats in each group, and they were administered continuously for 7 d. The tail vein blood was collec-ted after the last administration to detect the blood sugar and lipid levels in the rats. The serum levels of cardiac troponin I (cTnI), tumor necrosis factor-α (TNF-α), interleukin (IL)-1β and IL-10 were measured by ELISA. Echocardiography was used to detect the changes of cardiac function in the rats after blood collection. After cardiac function test, the rats were sacrificed to obtain cardiac tissues, and the volume changes of myocardial infarction were assessed by triphenylte-trazole chloride staining. The histopathological changes of myocardium was observed by HE staining. The cardiomyocyte apoptosis was determined by TUNEL assay. The protein levels of phosphorylated extracellular signal-regulated kinase (p-ERK), nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) in the myocardium were determined by Western blot. The myocardial activity of superoxide dismutase (SOD) was measured by nitro blue tetrazolium method, the content of malondialdehyde (MDA) was tested by thiobarbituric acid method, and the production of reactive oxygen species (ROS) was analyzed by iron ion reduction method. RESULTS: Compared with control group, the levels of fasting blood glucose (FBG), total cholesterol (TC) and triglyceride (TG) in DM-S group and DM+MIRI group were significantly elevated, while the level of high-density lipoprotein cholesterol (HDL-C) was significantly lowered (P<0.05). Compared with DM-S group and DM+MIRI group, the levels of FBG, TC, TG in TL, TM, TH and bardoxolone methyl groups were significantly decreased, while HDL-C level was significantly increased (P<0.05). Compared with control group and DM-S group, heart rate (HR) and left ventricular end-diastolic pressure (LVEDP) were increased in DM+MIRI group, mean arterial pressure (MAP), left ventricular systolic pressure (LVSP) and left ventricular ejection fraction (LVEF) were decreased, serum levels of cTnI, TNF-α, IL-1β and IL-10 were increased, the myocardial infarction volume percentage was increased, the myocardial cell breakage and necrosis were increased, the myocardial cell apoptotic rate was increased, the protein levels of p-ERK1/2, Nrf2 and HO-1 were decreased, MDA and ROS levels were increased, and the activity of SOD was decreased (P<0.05). Compared with DM+MIRI group, HR and LVEDP were decreased in TL, TM, TH and bardoxolone methyl groups, MAP, LVSP and LVEF were increased, the serum levels of cTnI, TNF-α, IL-1β and IL-10 were decreased, the myocardial infarction volume percentage was decreased, myocardial cell breakage and necrosis were decreased, myocardial cell apoptotic rate was decreased, the protein levels of p-ERK1/2, Nrf2 and HO-1 were increased, the MDA and ROS levels were decreased, and the activity of SOD was increased (P<0.05). CONCLUSION: Yiqi-Yangyin recipe protects the myocardial tissue of DM+MIRI rats from injury and reduces the oxidative stress level, which may be achieved by activating ERK/Nrf2/HO-1 pathway.     

Change of neurobiochemistry induced by renal ischemia-reperfusion injury

AIM:To explore the effects of renal ischemia-reperfusion injury on the changes of biochemistry in blood serum and cerebrospinal fluid. METHODS:Twenty healthy New Zealand rabbits were randomly divided into control group and renal ischemia-reperfusion injury group (IR group). The contents of creatinine (Cr), urea nitrogen (UN), Na+, Ca2+, metabolite of nitric oxide (NO) in blood serum and cerebrospinal fluid were detected and analyzed. The total activity of nitric oxide synthase (NOS) in brain tissues was also measured. RESULTS:Compared with control group, the contents of UN, Cr and NO were obviously higher (P<0.05), and the content of Na+ was obviously lower both in blood serum and cerebrospinal fluid in IR group than those in control at 24 h after renal ischemia-reperfusion injury. The content of Ca2+ was lower in blood serum but higher in cerebrospinal fluid in IR group compared with control group (P<0.05). Both the contents of NO2-/NO3- and the total activity of NOS in brain tissues were higher in IR group than those in control group (P<0.05). CONCLUSION:Not only elements of blood serum but also the biochemistry of cerebrospinal fluid were changed by renal ischemia-reperfusion injury. NO may involve in the influence of the renal ischemia-reperfusion injury on the cerebral function.     

Role of heme oxygenase-1 in the ischemic preconditioning of isolated rat heart

AIM: To investigate the influence of ischemic preconditioning on heart function, the activities of lactate dehydrogenase (LDH), malondialdehyde (MDA), and heme oxygenase-1 (HO-1) after ischemia/reperfusion in isolated rat heart. METHODS: The model of Langendorff was used in isolated rat heart perfusion. Ischemic preconditioning protocol: stopping perfusion for 5 minutes and reperfusion for 5 minutes, repeating three times. Ischemia protocol: stopping perfusion for 40 minutes and reperfusion for 20 minutes. Indexes of heart function were recorded in control M8, ischemia and reperfusion group (IR), and ischemic preconditioning group (IPC). The content of LDH of coronary effluent was measured. Moreover, the content of MDA and activity of HO-1 in myocardium were also measured. RESULTS: The recovery percentage of heart function in IPC group was significantly higher than that in IR group (P<0.01) and the activity of heme oxygenase-1 also increased significantly (P<0.05). CONCLUSION: The contents of LDH and MDA significantly decreased in IPC group compared with IR group. The increase in heme oxygenase-1 activity might be involved in the protective effect of ischemic preconditioning on ischemic/reperfused rat heart.