大鼠全脑缺血预处理后脑Mip1基因表达

目的探讨全脑缺血预处理后不同时间点鼠脑皮质、海马Mip1基因的表达及其与脑缺血耐受之间的关系。方法SD大鼠随机分成3组,建立大鼠全脑预缺血及缺血再灌注模型,其中2组通过脑水含量测定和组织学改变观察证实模型复制成功。第3组分为实验组(缺血预处理组)、假手术组,采用Northern杂交法检测Mip1在大鼠海马和前皮质在全脑缺血预处理后的表达情况。结果实验鼠全脑缺血3 min(预处理)后12 h组、24 h组海马和前皮质Mip1表达均高于假手术组。结论大鼠短暂非损伤性3 min缺血再灌注12 h、24 h后脑Mip1表达增高。Mip1表达增高可能是脑缺血耐受保护机制的一部分。

Hypoxia inducible factor-1α mediates protective effects of ischemic preconditioning on ECV-304 endothelial cells

AIM: To investigate whether hypoxia inducible factor-1α (HIF-1α) is linked to the protective effects of ischemic preconditioning (IP) on sinusoidal endothelial cells against ischemia/reperfusion injury. METHODS: Sinusoidal endothelial cell lines ECV-304 were cultured and divided into four groups: control group, cells were cultured in complete DMEM medium; cold anoxia/warm reoxygenation (A/R) group, cells were preserved in a 4℃ UW solution in a mixture of 95% N2 and 5% CO2 for 24 h; anoxia-preconditioning (APC) group, cells were treated with 4 cycles of short anoxia and reoxygenation before prolonged anoxia- preconditioning treatment; and anoxia-preconditioning and hypoxia inducible factor-1α (HIF-1α) inhibitor (I-HIF-1) group, cells were pretreated with 5 μm of HIF-1α inhibitor NS398 in DMEM medium before subjected to the same treatment as group APC. After the anoxia treatment, each group was reoxygenated in a mixture of 95% air and 5% CO2 incubator for 6 h. Cytoprotections were evaluated by cell viabilities from Trypan blue, lactate dehydrogenase (LDH) release rates, and intracellular cell adhesion molecule-1 (ICAM-1) expressions. Expressions of HIF-1α mRNA and HIF-1α protein from each group were determined by the RT-PCR method and Western blotting, respectively. RESULTS: Ischemia preconditioning increased cell viability, and reduced LDH release and ICAM-1 expressions. Ischemia preconditioning also upregulated the HIF-1α mRNA level and HIF-1α protein expression. However, all of these changes were reversed by HIF-1α inhibitor NS398.CONCLUSION: Ischemia preconditioning effectively inhibited cold hypoxia/warm reoxygenation injury to endothelial cells, and the authors showed for the first time HIF-1α is causally linked to the protective effects of ischemic preconditioning on endothelial cells.

Role of ischaemic preconditioning in liver regeneration following major liver resection and transplantation

Liver ischaemic preconditioning （IPC） is known to protect the liver from the detrimental effects of ischaemic-reperfusion injury （IRI）, which contributes significantly to the morbidity and mortality following major liver surgery. Recent studies have focused on the role of IPC in liver regeneration, the precise mechanism of which are not completely understood. This review discusses the current understanding of the mechanism of liver regeneration and the role of IPC in this setting. Relevant articles were reviewed from the published literature using the Medline database. The search was performed using the keywords ＂liver＂, ＂ischaemic reperfusion＇, ＂ischaemic preconditioning＂, ＂regeneration＂, ＂hepatectomy＂ and ＂transplantation＂. The underlying mechanism of liver regeneration is a complex process involving the interaction of cytokines, growth factors and the metabolic demand of the liver. IPC, through various mediators, promotes liver regeneration by up-regulating growth-promoting factors and suppresses growth-inhibiting factors as well as damaging stresses. The increased understanding of the cellular mechanisms involved in IPC will enable the development of alternative treatment modalities aimed at promoting liver regeneration following major liver resection and transplantation.

ISCHEMIC PRECONDITIONING RELIEVES ISCHEMIA/REPERFUSION INJURY OF HIPPOCAMPUS NEURONS IN RAT BY INHIBITING p53 AND BAX EXPRESSIONS

Objective To examine whether ischemic preconditioning (IPC) can protect neuron against delayed death in CA1 subfield of hippocampus following reperfusion of a lethal ischemia in rats, and explore the role of p53 and bax in this process. Methods We examined the effect of IPC on delayed neuron death, neuron apoptosis, expressions of p53 and bax gene in the CA1 area of hippocampus in the rats using HE staining, flow cytometry, RT-PCR, and immunohistochemistry technique. Results IPC enhanced the quantity of survival cells in the CA1 region of hippocampus (216±9 cells/0.72 mm2 vs. 30±5 cells/0.72 mm2, P<0.01), decreased the percentages of apoptotic neurons of hippocampus caused by ischemia/reperfusion (2.06%±0.21% vs. 4.27%±0.08%, P<0.01), and weakened the expressions of p53 and bax gene of hippocampus compared with ischemia/reperfusion without IPC. Conclusion IPC can protect the neurons in the CA1 region of hippocampus against apoptosis caused by ische- mia/reperfusion, and this process may be related to the reduced expressions of p53 and bax.

Effects of ischemic preconditioning on cyclinD1 expression during early ischemic reperfusion in rats

AIM： To observe the effect of ischemic preconditioning on cyclinD1 expression in rat liver cells during early ischemic reperfusion.METHODS： Fifty-four SD rats were randomly divided into ischemic preconditioning group （IP）, ischemia/ reperfusion group （IR） and sham operation group （SO）. The IP and IR groups were further divided into four sub-groups （n = 6）. Sham operation group （SO） served as the control group （n = 6）. A model of partial liver ischemia/reperfusion was used, in which rats were subjected to liver ischemia for 60 min prior to reperfusion. The animals in the IP group underwent ischemic preconditioning twice for 5 min each time prior to the ischemia/reperfusion challenge. Alter 0, 1, 2, and 4 h of reperfusion, serum and liver tissue in each group were collected to detect the level of serum ALT, liver histopathology and expression of cyclinD1 mRNA and protein. Flow cytometry was used to detect cell cycle as the quantity indicator of cell regeneration. RESULTS： Compared with IR group, IP group showed a significantly lower ALT level in 1h to 4h sub-groups （P 〈 0.05）. Proliferation index（PI） indicated by the S-phase and G2/M-phase ratio [（S＋G2/M）/（G0/G1＋S＋G2/M）] was significantly increased in IP group at 0 and 1 h （26.44 ± 7.60% vs 18.56 ± 6.40%,41.87 ± 7.27% vs 20.25 ± 6.70%, P 〈 0.05）. Meanwhile, cyclinD1 protein expression could be detected in IP group. But in IR group, cyclinD1 protein expression occurred 2 h alter reperfusion. The expression of cyclinD1 mRNA increased significantly in IP group at 0 and 1h （0.568 ± 0.112 vs 0.274 ± 0.069, 0.762 ± 0.164 vs 0.348 ± 0.093,P 〈 0.05）.CONCLUSION： Ischemic preconditioning can protect liver cells against ischemia/reperfusion injury, which may be related to cell proliferation and expression of cyclinD1 during early ischemic reperfusion.

Protective effects of ischemic preconditioning and application of lipoic acid prior to 90 min of hepatic ischemia in a rat model

AIM： To compare different preconditioning strategies to protect the liver from ischemia/reperfusion injury focusing on the expression of pro- and anti-apoptotic proteins. Interventions comprised different modes of ischemic preconditioning （IP） as well as pharmacologic pretreatment by α-lipoic acid （LA）. METHODS： Several groups of rats were compared： sham operated animals, non-pretreated animals （nt）, animals receiving IP （10 rain of ischemia by clamping of the portal triad and 10 min of reperfusion） prior to sustained ischemia, animals receiving selective ischemic preconditioning （IPsel, 10 min of ischemia by selective clamping of the ischemic lobe and 10 rain of reperfusion） prior to sustained ichemia, and animals receiving 500 1μmol α-LA injected i.v. 15 min prior to the induction of 90 min of selective ischemia. RESULTS： Cellular damage was decreased only in the LA group. TUNEL-positive hepatocytes as well as necrotic hepatocyte injury were also decreased only by LA（19 ± 2 vs 10 ± 1, P〈 0.05 and 29 ± 5 vs 12 ± 1, P 〈 0.05）. Whereas caspase 3- activities in liver tissue were unchanged, caspase 9- activity in liver tissue was decreased only by LA pretreatment （3.1 ± 0.3 vs 1.8 ± 0.2, P 〈 0.05）. Survival rate as the endpoint of liver function was increased after IP and LA pretreatment but not after IPsel. Levels of lipid peroxidation （LPO） in liver tissue were decreased in the IP as well as in the LA group compared to the nt group. Determination of pro- and anti-apoptotic proteins showed a shift towards anti-apoptotic proteins by LA. In contrast, both our IP strategies failed to influence apototic cell death. CONCLUSION： IP, consisting of 10 min of ischemia and 10 min of reperfusion, ischemia/reperfusion injury protects only partly against of the liver prior to 90 min of selective ischemia. IPsel did not influence ischemic tolerance of the liver. LA improved tolerance to ischemia, possibly by downregulation of pro-apoptotic Bax.

EFFECTS OF GLIBENCLAMIDE, GLIMEPIRIDE, AND GLICLAZIDE ON ISCHEMIC PRECONDITIONING IN RAT HEART

Objective To compare the influence of different sulfonylureas on the myocardial protection effect of ischemic preconditioning (IPC) in isolated rat hearts, and ATP-sensitive potassium channel current (IKATP) of rat ventricular myocytes. Methods Isolated Langendorff perfused rat hearts were randomly assigned to five groups: (1) control group, (2) IPC group, (3) IPC+glibenclamide (GLB, 10 μmol/L) group, (4) IPC+glimepiride (GLM, 10 μmol/L) group, (5) IPC+gliclazide (GLC, 50 μmol/L) group. IPC was defined as 3 cycles of 5-minute zero-flow global ischemia followed by 5-minute reperfusion. The haemodynamic parameters and the infarct size of each isolated heart were recorded. And the sarcolemmal IKATP of dissociated ventricular myocytes reperfused with 10 μmol/L GLB, 1 μmol/L GLM, and 1 μmol/L GLC was recorded with single-pipette whole-cell voltage clamp under simulated ischemic condition. Results The infarct sizes of rat hearts in IPC (23.7%±1.3%), IPC+GLM (24.6%±1.0%), and IPC+GLC (33.1%±1.3%) groups were all significantly smaller than that in control group (43.3%±1.8%; P<0.01, n=6). The infarct size of rat hearts in IPC+GLB group (40.4%±1.4%) was significantly larger than that in IPC group (P<0.01, n=6). Under simulated ischemic condition, GLB (10 μmol/L) decreased IKATP from 20.65±7.80 to 9.09±0.10 pA/pF (P<0.01, n=6), GLM (1 μmol/L) did not significantly inhibit IKATP (n=6), and GLC (1 μmol/L) decreased IKATP from 16.73±0.97 to 11.18±3.56 pA/pF(P<0.05, n=6). Conclusions GLM has less effect on myocardial protection of IPC than GLB and GLC. Blockage of sarcolemmal ATP-sensitive potassium channels in myocardium might play an important role in diminishing IPC-induced protection of GLM, GLB, and GLC.

Impact of remote ischemic preconditioning on wound healing in small bowel anastomoses

AIM： To investigate the influence of remote ischemic preconditioning （RIPC） on anastomotic integrity. METHODS： Sixty male Wistar rats were randomized to six groups. The control group （n = 10） had an end- to-end ileal anastomosis without RIPC. The preconditioned groups （n = 34） varied in time of ischemia and time of reperfusion. One group received the amino acid L-arginine before constructing the anastomosis （n = 9）. On postoperative day 4, the rats were re-laparotomized, and bursting pressure, hydroxyproline concentration, intra-abdominal adhesions, and a histological score concerning the mucosat ischemic injury were collected. The data are given as median （range）.RESULTS： On postoperative day 4, median bursting pressure was 124 mmHg （60-146 mmHg） in the control group. The experimental groups did not show a statistically significant difference （P 〉 0.05）. Regarding the hydroxyproline concentration, we did not find any significant variation in the experimental groups. We detected significantly less mucosal injury in the RIPC groups. Furthermore, we assessed more extensive intra-abdominal adhesions in the preconditioned groups than in the control group. CONCLUSION： RIPC directly before performing small bowel anastomosis does not affect anastomotic stability in the early period, as seen in ischemic preconditioning.

Organ preconditioning: the past, current status, and related lung studies

Preconditioning (PC) has emerged as a powerful method for experimentally and clinically attenuating various types of organ injuries. In this paper related clinical and basic research issues on organ preconditioning issues were systemically reviewed. Since lung injuries, including ischemia-reperfusion and others, play important roles in many clinical results, including throm-boembolism, trauma, thermal injury, hypovolemic and endotoxin shock, reimplantation response after organ transplantation, and many respiratory diseases in critical care. It is of interest to uncover methods, including the PCs, to protect the lung from the above injuries. However, related studies on pulmonary PC are relatively rare and still being developed, so we will review previous literature on experimental and clinical studies on pulmonary PC in the following paragraphs.

Cardiac Remote Conditioning and Clinical Relevance:All Together Now!

Acute myocardial infarction （AMI） is the leading cause of death and disability worldwide. Timely reperfusion is the standard of care and results in decreased infarct size, improving patient survival and prognosis. However, 25% of patients proceed to develop heart failure （HF） after myocardial infarction （MI） and 50% of these will die within five years. Since the size of the infarct is the major predictor of the outcome, including the development of HF, therapies to improve myocardial salvage have great potential. Over the past three decades, a number of stimuli have been discovered that activate endogenous cardioprotective pathways. In ischemic preconditioning （IPC） and ischemic postconditioning, ischemia within the heart initiates the protection. Brief reversible episodes of ischemia in vascular beds remote from the heart can also trigger cardioprotection when applied before, during, or immediately after myocardial ischemia-- known as remote ischemic pre-, per-, and post-conditioning, respectively. Although the mechanism of remote ischemic preconditioning （RIPC） has not yet been fully elucidated, many mechanistic components are shared with IPC. The discovery of RIPC led to research into the use of remote non-ischemic stimuli including nerve stimulation （spinal and vagal）, and electroacupuncture （EA）. We discovered and, with others, have elucidated mechanistic aspects of a non- ischemic phenomenon we termed remote preconditioning of trauma （RPCT）. RPCT operates via neural stimulation of skin sensory nerves and has similarities and differences to nerve stimulation and EA conducted at acupoints. We show herein that RPCT can be mimicked using electrical stimulation of the abdominal midline （EA-like treatment） and that this modality of activating cardioprotection is powerful as both a preconditioning and a postconditioning stimulus （when applied at reperfusion）. Investigations of these cardioprotective phenomena have led to a more integrative understanding of mechanisms related to cardioprotection, and in the last five to ten years, it has become clear that the mechanisms are similar, whether induced by ischemic or non-ischemic stimuli. Taking together much of the data in the literature, we propose that all of these cardioprotective ＂conditioning＂ phenomena represent activation from different entry points of a cardiac conditioning network that converges upon specific mediators and effectors of myocardial cell survival, including NF-KB, Stat3/5, protein kinase C, bradykinin, and the mitoKA^P channel. Nervous system pathways may represent a novel mechanism for initiating conditioning of the heart and other organs. IPC and RIPC have proven difficult to translate clinically, as they have associated risks and cannot be used in some patients. Because of this, the use of neural and nociceptive stimuli is emerging as a potential non-ischemic and non-traumatic means to initiate cardiac conditioning. Clinical relevance is underscored by the demonstration of postconditioning with one of these modalities, supporting the conclusion that the development of pharmaceuticals and electroceuticals for this purpose is an area ripe for clinical development.

Protective effect of L-arginine preconditioning on ischemia and reperfusion injury associated with rat small bowel transplantation

AIM: To investigate the protective effect and possible mechanism of L-arginine preconditioning on ischemia and reperfusion injury associated with small bowel transplantation (SBT).METHODS: Male inbred Wistar rats weighting between 180 and 250 g were used as donors and recipients in thestudy. Heterotopic rat SBT was performed according to the techniques of Li and Wu. During the experiment, intestinal grafts were preserved in 4 ℃ Ringer's solution for 8 h before being transplanted. Animals were divided into three groups. In group 1, donors received intravenous L-arginine (50 mg/kg, 1 mL) injection 90 min before graft harvesting. However, donors in control group were given normal saline (NS) instead. In group 3, six rats were used as sham-operated control. Specimens were taken from intestinal grafts 15 min after reperfusion. Histological grading, tissue malondialdehyde (MDA) and myeloperoxidase (MPO) levels were assessed. The graft survival of each group was monitored daily until 14 d after transplantation. RESULTS: Levels of MDA and MPO in intestine of shamoperated rats were 2.0±0.22 mmol/g and 0.66±0.105 U/g. Eight hours of cold preservation followed by 15 min of reperfusion resulted in significant increases in tissue MDA and MPO levels. Pretreatment with L-arginine before graft harvesting resulted in lower enhancement of tissue levels of MDA and MPO and the differences were significant (4.71±1.02 mmol/g vs8.02±3.49 mmol/g, 1.03±0.095 U/g vs 1.53±0.068 U/g, P＜0.05). Besides, animals in L-arginine pretreated group had better histological structures and higher 2-wk graft survival rates comparing with that in NS treated group (3.3±0.52 vs6±0.1, 0/6 vs6/6, P＜0.05or 0.01).CONCLUSION: L-arginine preconditioning attenuates ischemia and reperfusion injury in the rat SBT model,which was due to antioxidant activities partially.

Protection of preconditioning,postconditioning and combined therapy against hepatic ishemia/reperfusion injury

Objective： To study the protective effect of ischenlic preconditioning （I-pre） and ischemic postconditioning （I- post） against ischenlia/reperfusion （I/R） injury in rat＇ s liver. Methods： Using rat model of hepatic segmental I/R injury, rats were divided into 5 groups： Group A （sham group）, Group B （I/R injury）, Group C （I-pre group）, Group D （I-post group ） and Group E （combined treatment of I-pre and I-post ）. Serum alanine aminotransferase （ ALT ）, aspartate aminotransferase （ AST）, malondiaidehyde （ MDA ）, glutathione （ GSH ）, superoxide dismutase （ SOD ）, glutathione peroxidase （GSH-Px） and myeloperoxidase （MPO） in hepatic tissues were determined, respectively. In addition, 7 days＇survival of Groups B, C, D and E were evaluated. Results. Compared with Group B, Groups C, D and E exhibited significantly decreased ALT and AST release, minimized tissue injury, suppressed values of MDA and MPO, increased activities of SOD, GSH-Px and GSH （P〈0.05 ）, as well as improved animal survival. The differences among Groups C, D and E were not statistically significant. Conclusions： I-pre, I-post and combined therapy of I-pre and I-post have protective effect against hepatic I/R injury, which is correlated with its function of reducing the production of reactive oxygen species, maintaining the activities of antioxidant systems and suppressing neutrophils recruitment. No additive effect can be obtained in Group E.

Protective effect of ischemic preconditioning on liver

Objective:: To study the protective effect of ischemic preconditioning (IPC) on the hepatic ischemia-reperfusion injury. Methods: The model of rat liver subjected to ischemia/reperfusion (I/R) injury was made. All 24 mice were divided randomly into 3 groups and anesthetized by 2% sodium pentobarbital (30-40 mg/kg). The enzyme activity of AST, ALT, LDH, SOD and the content of LPO were assayed respectively. Specimens were observed under transmission electron microscope. Results: IPC prevented the increase of ALT, AST and LDH in the blood and that of LPO in the tissues (P< 0.05 ), and maintained high level of SOD in the tissues (P< 0.05 ). Conclusions: IPC has protective effect on the liver function.

Cardioprotective effects of anesthetic preconditioning in rats with ischemia-reperfusion injury: propofol versus isoflurane

Objective： We compare the cardioprotective effects of anesthetic preconditioning by propofol and/or isoflurane in rats with ischemia-reperfusion injury. Methods： Male adult Wistar rats were subjected to 60 min of anterior descending coronary artery occlusion followed by 120 rain of reperfusion. Before the long ischemia, anesthetics were administered twice for 10 min followed by 5 min washout. Isoflurane was inhaled at 1 MAC （0.016） in I group, whereas propofol was inhaled intravenously at 37.5 mg/（kg.h） in P group. A combination ofisoflurane and propofol was administered simultaneously in I＋P group. Results： In control （without anesthetic preconditioning, C group）, remarkable myocardial infarction and apoptosis accompanied by an increased level of cardiac troponin T were noted 120 min aider ischemia-reperfusion. As compared to those of control group, I and P groups had comparable cardioprotection. In addition, I＋P group shares with I and P groups the comparable cardioprotective effects in terms of myocardial infarction and cardiac troponin T elevation. Conclusion： A combination of isoflurane and propofol produced no additional cardioprotection.

Protective effect of electroacupuncture preconditioning at zúsānlǐ(足三里 ST36) on mitochondria in the intestinal ischemia/reperfusion injury

Objective： The study explored the effect of applying electroacupuncture（EA） preconditioning at ST 36 on mitochondria in rats with intestinal ischemia/reperfusion injury.Methods： Forty SD rats were divided into four sets： sham operation group（sham group）; intestinal ischemia/reperfusion group（I/R group）; EA preconditioning at ST 36 followed by intestinal ischemia/reperfusion injury（ST 36 ＋ I/R group）; EA preconditioning at the lateral site away from ST360.5 cm followed by intestinal ischemia/reperfusion injury（N＋I/R group）. For the sham group, the rats were opened abdominal cavity for 3 h and 20 min and their abdominal cavities were covered with wet gauze avoiding drying and kept on the thermostat at 37 0 C. For the ischemia/reperfusion（I/R） group,rats were anaesthetised and their abdominal cavities were opened to expose jejunum segments. The segment＇s collateral blood supply was restricted by bilateral ligation of the intestine. Next, one of the branches of a mesenteric artery was occluded with a thread for 20 min and then the thread was released after such ischemia conditions, keeping reperfusion for 3 h. For the ST36 ＋ I/R group, the electroacupuncture at ST36 was first performed, then the intestinal ischemia/reperfusion model was constructed. For the N ＋ I/R group, electroacupuncture at non ST36 acupoint, which is away from ST36 about 0.5 cm, and then the intestinal ischemia/reperfusion model was performed. Measurements of the levels of inflammatory markers tumour necrosis factor a（TNFa） and interleukin-1 beta（IL-1β）, cytochrome c（CYCS）, and the mitochondrial membrane pro-apoptotic protein（BAX）, anti-apoptotic protein Bcl-2 were performed.Results： Compared to I/R group, the intensity of cytoplasmic CYCS in intestinal tissues was significantly decreased in the ST 36 ＋ I/R group（1.65 vs. 0.18, p〈0.05）. Compared to N ＋ I/R group, the intensity of cytoplasmic CYCS in intestinal tissues was also dramatically declined in the ST 36 ＋ I/R group（1.37 vs. 0.18, p〈0.05）. The level of CYCS in mitochondria in rats in the ST 36 ＋ I/R group were appreciably increased than those of rats in the I/Rgroup（1.42 vs. 0.06, p〈0.05）, and CYCS in mitochondria was also largely expressed in ST36 ＋ I/R group than N ＋ I/R group（1.42 vs. 0.08, p〈0.05）. Bcl-2 was shown to be elevated in the ST 36 ＋ I/R group than I/R group（1.01 vs. 0.10） and N ＋ I/R group（1.01 vs. 0.09, all p〈0.05）, whereas BAX expression was greatly decreased in the ST36 ＋ I/R group than I/R group（0.11 vs.0.78） and N ＋ I/R group（0.11 vs. 0.87, all p〈0.05）.Conclusion： The results suggest the EA intervention has a protective effect upon mitochondria, preventing CYCS release and the subsequent activation of downstream apoptosis pathway. It is proposed that patients due to undergo gastrointestinal surgery get benefit from EA preconditioning at ST 36.