Effects of phytoestrogen genistein on myocardial ischemia／reperfusion injury and apoptosis in rabbits

INTRODUCTION Ischemia/reperfusion (I/R) injury is often seen inclinics which pathogenesis has not been elucidatedclearly. It is generally believed that its mechanism isrelated to lipid peroxide induced by oxygen free radi-cals and to irreversible damage caused by intracellularcalcium overload. The Ca2 overload is induced mainlyby the action of sarcolemmal Na /H and Na /Ca2 ex-changers[1,2], which then activates several intracellularprocess, resulting in myocyte death[3-5]. Genistein…     

Neuroprotective effects of scutellarin on rat neuronal damage induced by cerebral ischemia/reperfusion

AIM: To investigate the neuroprotective effect and mechanisms of scutellarin, a flavonoid extracted from Erigeron breviscapus Hand Mazz, against neuronal damage following cerebral ischemia/reperfusion. METHODS: Rats were pretreated ig with scutellarin for 7 d and then subjected to cerebral ischemia/reperfusion (I/R) injury induced by a middle cerebral artery occlusion (MCAO). The infarct volume and neurological deficit were determined by TTC staining and Longa's score. The permeability of the blood-brain barrier was evaluated by measurement of the Evans blue (EB) content in the brain with a spectrophotometer. The total NOx content was determined. Nitric oxide synthase (NOS) isoforms (iNOS, eNOS, nNOS) and the key angiogenic molecules, vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF), were detected by Western blotting. RESULTS: Scutellarin significantly reduced infarct volume (P<0.05 or P<0.01), ameliorated the neurological deficit and reduced the permeability of the blood-brain barrier (BBB) (P<0.05). When rats were pretreated with scutellarin (50 or 75 mg/kg), upregulation of eNOS expression and downregulation of VEGF, bFGF, and iNOS expression was observed, whereas scutellarin had no effect on nNOS expression. CONCLUSION: Scutellarin has protective effects for cerebral injury through regulating the expression of NOS isoforms and angiogenic molecules.     

硫化氢对肝缺血再灌注损伤动物模型保护作用的Meta分析

目的 系统评价硫化氢对肝缺血再灌注损伤动物模型的保护作用.方法 计算机检索中国知网CNKI、万方Data、PubMed和Cochrane Library,查找硫化氢对肝缺血再灌注损伤保护作用研究的动物实验.研究者独立地按照纳入与排除标准筛选文献、提取资料,然后通过Quadas质量评价标准评估纳入文献质量.采用RevMan 5.3软件进行 Meta分析.结果 最终纳入 7 篇文献,包括48只大鼠.Meta 分析结果 显示:缺血组丙氨酸氨基转移酶(ALT)水平高于假手术组[SMD=-5.49,95%CI为(-7.46~-3.53),P=0.001];硫化氢组ALT水平低于缺血组[SMD=-3.69,95%CI为(-5.36~-2.02),P=0.000 01];硫化氢组ALT水平高于假手术组[SMD=1.80,95%CI为(1.26~2.35),P=0.000 01],以上ALT比较均差异有统计学意义.结论 根据现有的资料显示,硫化氢对肝缺血再灌注损伤有保护作用.但受纳入研究样本量所限,该结论 尚需更多高质量实验来验证.     

绒毛钩藤树皮煎剂中原花青素的抗炎机理——抗氧化活性研究

太得恩（Tadenan）为非洲臀果木Pygeurn africanum提取物的制剂，在欧洲用于治疗良性前列腺肥大。作者研究了以太得恩预处理，对兔膀胱双侧缺血-再灌注引起的收缩功能障碍是否具有防治作用。     

乌司他丁对幼兔未成熟心肌缺血再灌注损伤的保护作用

目的:研究乌司他丁对幼兔离体心脏缺血再灌注损伤的保护作用.方法:建立幼兔离体心脏Langendorff模型,灌注停跳液使心脏停跳30 min,用加入乌司他丁的K-H液复灌30 min.于缺血前0 min,复灌后10、20、30 min记录心率(HR)、左室内压(LVP)、左室内压最大上升速率(LVdp/dt)、冠脉流量(CF);于缺血前1 min,复灌后10、20、30min测定冠状静脉流出液中肌酸激酶(CK)、肌钙蛋白(cTnI)、肿瘤坏死因子(TNF-α)、白细胞介素6(IL-6)的浓度.结果:(1)乌司他丁组心脏复灌后HR、CF、LVdp/dtmax均升高(P<0.05或P<0.01);冠状静脉流出液CK、cTnI、TNF-α、IL-6浓度均低于对照组(P<0.01).(2)对照组心肌细胞横纹模糊不清,可见多灶性细胞崩解,心肌纤维断裂,间质充血、出血并有中性粒细胞和淋巴细胞浸润;乌司他丁组心肌细胞胞浆嗜伊红均质浓染,可见局灶性细胞崩解,间质充血只有少量淋巴细胞浸润.结论:乌司他丁能明显减轻幼兔未成熟心肌缺血再灌注损伤.     

Effect of Gαq／11 protein and ATP-sensitive potassium channels on prostaglandin E1 preconditioning in rat hearts

To investigate the effect of G~11 signaling pathway and ATP-sensitive potassium channels (KAxP channels) on prostaglandin E1 (PGE0 induced early and delay-preconditioning protection in rat hearts. METHODS: Two series of experiments were performed in Wistar rat hearts. In the first series of experiment, all rats were pretreated with PGE 40 min or 23 h 20 min before the experiment. Ischemia-reperfusion injury was induced by 30 min coronaryartery occlusion followed by 90 min reperfusion. Hemodynamics, infarct size, and scores of ventricular arrhythmias were measured. The expression of G~q/H protein in the heart was measured by Western blot analysis in the second series. RESULTS: Preconditioning with PGE~ (25 lag/kg ) markedly reduced infarct size, left ventricular enddiastolic pressure, and scores of ventricular arrhythmia. The effect of PGE1 was significantly attenuated by glibenclamide (1 mg/kg, ip), a nonselective KA~ channel inhibitor. PGE~ caused a significant increase in the expression of G~/~ protein. CONCLUSION: Activations of G~/H signal pathway and Kgrp channel played significantroles in the cardioprotection of PGE~ preconditioning in rat heart and might be an important mechanism of signal transduction pathway during the PGEj preconditioning.     

Melatonin in cardiac ischemia/reperfusion-induced mitochondrial adaptive changes

Due to its small size and amphiphilic nature, indoleamine melatonin is able to reach all cell compartments quickly. The highest Melatonin concentrations are to be found in the mitochondria, and cytochrome c (cyt c) represents a Melatonin target, since Melatonin is able to oxidise organic molecules in the presence of physiological amounts of hydrogen peroxide (H(2)O(2)). The mitochondrial cyt c-mediated oxidation of melatonin depends on oxoferrylheme in two one-electron steps. The protective effects of Melatonin against cardiac ischemia/reperfusion (I/R)-induced mitochondrial oxidative damage are well documented as an antioxidant agent which prevents and/or modulates the production of reactive oxygen species (ROS) responsible for the reperfusion injury. On the basis of our previous studies on ischemia/reperfusion (I/R) in human cardiomyocytes it has become clear that severe hypoxic and ischemic stimuli evoke a mitochondrial response in terms of the functional adaptation of cyt c oxidase (COX) to oxygen altered availability. Most, if not all, data are compatible with a mechanism of adaptation, in which nitric oxide (NO) generation is now considered as the major player. The NO-induced COX inhibition represents a key point in ischemia-induced, adaptive changes, since a balanced oxidative metabolism between lower O(2) concentrations and COX catalytic capacity down-regulation is thus obtained. This mechanism is a limiting factor in the cardiac ischemia-induced ROS mitochondrial generation. In the light of this concept and if we consider melatonin to be strongly active in cyt c up-regulation, it is obvious that the use of this molecule in the course of cardiac ischemia could be deleterious. On the contrary, the prompt restoration of the coronary blood flow is inexorably associated with the so-called "reperfusion syndrome" and/or with a condition of myocardial stunning. These phenomena are strictly linked to the aforementioned ischemia-induced cyt c adaptive changes, for the reason that a primary imbalance is induced between the persistent down-regulated enzymatic oxidative capacity and mitochondrial oxygen gradients are rapidly restored. This leads to a massive ROS neo-generation, which evokes well-known cellular disorders. In this scenario the melatonin treatment could play a pivotal role in terms of a cyt c up-regulating agent, crucial for counteracting most, if not all the biochemical and molecular phenomena, on which the clinical symptoms proper of myocardial reperfusion syndrome are based.     

Ischemic preconditioning reduces the severity of ischemia/reperfusion-induced pancreatitis

In various organs, including heart, kidneys, brain, liver and stomach, preconditioning by brief exposure to ischemia protects the organ against damage evoked by subsequent severe ischemia. This study has been undertaken to check whether two brief ischemic periods protect the pancreas against severe ischemia/reperfusion-induced pancreatitis and, if so, what is the role of sensory and vagal nerves in this phenomenon. In male Wistar rats, the ischemic preconditioning of the pancreas was performed by clamping of celiac artery (2 x 5 min with 5 min interval). Thirty minutes after preconditioning or sham operation, the ischemia/reperfusion-induced pancreatitis was evoked by clamping of inferior splenic artery for 30 min using microvascular clips, followed by 1 h reperfusion. Sensory nerves ablation was induced 10 days before final experiments by capsaicin. Truncal vagotomy was performed 1 week before the experiment. Exposure to regular 30-min pancreatic ischemia followed by 1 h reperfusion led to the development of acute hemorrhagic pancreatitis. Ischemic preconditioning, applied prior to induction of pancreatitis, caused the reduction in plasma lipase, plasma interleukin-1beta and histological signs of pancreatic damage, as well as attenuated the reduction in pancreatic blood flow and DNA synthesis. Ablation of sensory nerves by capsaicin caused an aggravation of ischemia/reperfusion-induced pancreatic damage and attenuated a protective effect of ischemic preconditioning. Noxious effect of sensory nerves ablation on the pancreas was accompanied by the reduction in pancreatic blood flow and an increase in plasma interleukin-1beta. Similar but less pronounced deleterious effect on the pancreas was observed after vagotomy. We conclude that: (1) pancreatic ischemic preconditioning reduces the severity of ischemia/reperfusion-induced pancreatitis; (2) this effect seems to be related, at least in part, to the improvement of pancreatic blood flow and the reduction in the release of proinflammatory interleukin-1beta; (3) sensory and vagal nerves are involved in protective effect of ischemic preconditioning against pancreatic damage.     

Protective effect of agmatine on ischemia/reperfusion-induced renal injury in rats

Enhanced renal sympathetic nerve activity (RSNA) during ischemic period and the renal venous norepinephrine (NE) overflow after reperfusion play important roles in the development of ischemic/reperfusion (I/R)-induced acute renal failure (ARF) in rats. This study evaluated whether agmatine, which is known to reduce sympathetic nerve activity and NE overflow by electrical stimulation, would prevent the I/R-induced renal dysfunction. Ischemic ARF was induced by clamping the left renal artery and vein for 45 minutes followed by reperfusion 2 weeks after the contralateral nephrectomy. Intravenous (IV) injection of agmatine (100 and 300 micromol/kg) to ischemic ARF rats dose-dependently suppressed the enhanced RSNA and attenuated the I/R-induced renal dysfunction and histological damage. Intracerebroventricular (ICV) injection of agmatine (600 nmol/kg) to ischemic ARF rats suppressed the enhanced RSNA during the ischemic period and attenuated the I/R-induced renal injury. Furthermore, both IV and ICV injection of agmatine significantly suppressed the renal venous NE overflow after the reperfusion. These results indicate that agmatine prevents the development of I/R-induced renal injury, and the effect is accompanied by suppression of the enhanced RSNA during ischemic period and NE overflow from renal sympathetic nerve endings.     

Dietary supplementation of L-carnosine prevents ischemia/reperfusion-induced renal injury in rats

The effects of dietary supplementation of L-carnosine (beta-alanyl-L-histidine) on ischemia/reperfusion-induced acute renal failure (ARF) in rats were examined. Ischemic ARF was induced by occlusion of the left renal artery and vein for 45 min followed by reperfusion, 2 weeks after contralateral nephrectomy. Renal functional parameters such as blood urea nitrogen, plasma creatinine, creatinine clearance, urine flow, urinary osmolality and fractional excretion of sodium were measured. Renal function in ARF rats markedly decreased at 1 d after reperfusion. Prior feeding of L-carnosine-containing diet (0.0001 w/w%) for 2 weeks attenuated the ischemia/reperfusion-induced renal dysfunction. Histopathological examination of the kidney of ARF rats revealed severe renal damages, such as tubular necrosis, proteinaceous casts in tubuli and medullary congestion, which were also significantly suppressed by the dietary supplementation of L-carnosine. These findings strongly suggest that L-carnosine supplementation is useful as a prophylactic treatment in the development of the ischemic ARF.     

Adenosine reduces ischemia/reperfusion-induced liver injury by inhibiting leukocyte activation

To examine whether adenosine reduces ischemia/reperfusion (I/R)-induced liver injury by inhibiting leukocyte activation via A2 receptor (A2R), we investigated the effects of adenosine and YT-146, selective A2A receptor (A2AR) agonist, on I/R-induced liver injury in rats. Adenosine and YT-146, in the range of concentrations of 10(-7)-10(-5) M, significantly inhibited the formyl-methionyl-leucyl-phenylalanine (fMLP)-induced neutrophil elastase release from isolated neutrophils by about 35% in vitro. Adenosine and YT-146, in the range of concentrations of 10(-7)-10(-5) M, significantly inhibited the endotoxin-stimulated TNF-alpha production by monocytes to less than 50% of the control. Although ZM241385, a selective A2AR antagonist, significantly enhanced the fMLP-induced neutrophil elastase release in isolated neutrophils in vitro, this agent did not affect the endotoxin-stimulated TNF-alpha production by monocytes. Male Wistar rats were subjected to complete ischemia of median and left lobes of liver for 60 min and the subsequent reperfusion. Serum levels of transaminases increased over time after hepatic I/R, peaking at 12 hrs after reperfusion. Intravenous infusion of Adenosine (1 and 10 mg/kg/hr) and YT-146 (0.1 and 1 mg/kg/hr) significantly inhibited the I/R-induced increases in serum transaminase levels 12 hrs after reperfusion. The I/R-induced decrease in hepatic tissue blood flow was significantly inhibited by adenosine and YT-146. Hepatic levels of TNF-alpha, cytokine-induced neutrophil chemoattractant (a member of interleukin-8), and myeloperoxidase were significantly increased after I/R. These increases were significantly inhibited by administration of adenosine and YT-146. However, ZM241385 did not reduce the I/R-induced liver injury and it inhibited neither the decrease in hepatic tissue blood flow, nor the indicators of leukocyte activation. These findings suggest that adenosine may reduce I/R-induced liver injury mainly by inhibiting hepatic TNF-alpha production via A2AR, thereby reducing neutrophil activation.     

蝙蝠葛碱抗缺血/再灌注性室颤及其机制

目的：探讨蝙蝠葛碱抗缺血／再灌注性室颤的机理。方法：用高效液相色谱－电化学法测定豚鼠离体心脏灌注液中去甲肾上腺素（NE）含量。结果：蝙蝠葛碱组和维拉帕米组在停止灌注时心脏NE释放量明显低于对照组（P＜0．01），缺血／再灌注性室颤发生率显著低于对照组（P＜0．05）。发生缺血／再灌注性室颤的心脏NE释放量明显高于无缺血／再灌注性室颤心脏（P＜0．01）。停止灌注时心脏NE释放量和缺血／再灌注性室颤发生率，在蝙蝠葛碱组与维拉帕米组之间无显著差异（P＞0．05）。结论：蝙蝠葛碱抑制缺血心肌NE释放为其抗缺血／再灌注性室颤的机理之一。     

Preventive effect of flavangenol on ischemia/reperfusion-induced acute renal failure in rats

The effects of flavangenol on ischemia/reperfusion-induced acute renal failure (ARF) in rats were examined. Ischemic ARF was induced by occlusion of the left renal artery and vein for 45 min followed by reperfusion, 2 weeks after contralateral nephrectomy. Renal functional parameters such as blood urea nitrogen, plasma creatinine, creatinine clearance, urine flow, urinary osmolality and fractional excretion of sodium were measured. Renal function in ARF rats markedly decreased at 1 d after reperfusion. Pre-ischemic treatment with flavangenol (3-30 mg/kg, i.v.) attenuated the ischemia/reperfusion-induced renal dysfunction. Histopathological examination of the kidney of ARF rats revealed severe renal damage, such as tubular necrosis and proteinaceous casts in tubuli, which were also significantly suppressed by the administration of flavangenol. These findings suggest that flavangenol supplementation may be a promising candidate for treatments to improve the ischemia/reperfusion-induced renal injury.     

Angiotensin AT1 receptor blockers suppress ischemia/reperfusion-induced gastric injury in rats

Ischemia/reperfusion (I/R) damages gastric mucosa via reactive oxygen species (ROS) activity. ROS was reportedly produced through angiotensin II stimulation in tissues such as kidney, heart and brain. To determine whether AT1 receptor plays a role in gastric mucosal damage, we examined the effect of AT1 receptor blocker (ARB; losartan, candesartan, valsartan) on I/R-induced gastric injury in rats. I/R produced microscopic gastric hemorrhagic injury, and increased gastric microvascular permeability and H₂O₂ production in rats. The mucosal lesions induced by I/R were attenuated by pretreatment of each ARB. The increase in microvascular permeability was suppressed by losartan pretreatment. Additionally, I/R-caused H₂O₂ activation was not observed by pretreatment of losartan, candesartan and valsartan. These results suggest that angiotensin II stimulation via AT1 receptor and following ROS production in the stomach contribute to the pathogenesis of the gastric I/R injury. Received 31 July 2006; revised 29 August 2006; accepted 21 August 2006     

Preventive effect of L-carnosine on ischemia/reperfusion-induced acute renal failure in rats

We investigated the effect of L-carnosine (beta-alanyl-L-histidine) on ischemic acute renal failure in rats. Ischemic acute renal failure was induced by occlusion of the left renal artery and vein for 45 min followed by reperfusion, 2 weeks after contralateral nephrectomy. Renal function in untreated acute renal failure rats markedly decreased at 1 day after reperfusion. Pre-ischemic treatment with L-carnosine dose-dependently (1, 10 microg/kg, i.v.) attenuated the ischemia/reperfusion-induced renal dysfunction. Histopathological examination of the kidney of untreated acute renal failure rats revealed severe renal damage, which was significantly suppressed by pre-treatment with L-carnosine, at each dose given. In untreated acute renal failure rats, norepinephrine concentrations in renal venous plasma remarkably increased within 2 min after reperfusion and thereafter rapidly decreased. Pre-ischemic treatment with L-carnosine at a dose of 10 microg/kg significantly depressed the elevated norepinephrine level. On the other hand, although the higher dose of L-carnosine given 5 min after reperfusion tended to ameliorate the renal dysfunction after reperfusion, the improvement was moderate compared with those seen in pre-ischemic treatment. These results indicate that L-carnosine prevents the development of ischemia/reperfusion-induced renal injury, and the effect is accompanied by suppression of the enhanced norepinephrine release in the kidney immediately after reperfusion. Thus, the preventing effect of L-carnosine on ischemic acute renal failure is probably through the suppression of enhanced renal sympathetic nerve activity induced by ischemia/reperfusion.     

Effects of administration of nicorandil or bimakalim prior to and during ischemia or reperfusion on survival rate, ischemia/reperfusion-induced arrhythmias and infarct size in anesthetized rabbits

We investigated the effects of administration of non-hypotensive doses of ATP-sensitive K+ channel (KATP) openers (nicorandil and bimakalim), and a specific mitochondrial KATP channel blocker (5-hydroxydecanoate) prior to and during coronary occlusion as well as prior to and during post-ischemic reperfusion on survival rate, ischemia-induced and reperfusion-induced arrhythmias and myocardial infarct size in anesthetized albino rabbits. The thorax was opened in the left fourth intercostal space and after pericardiotomy the heart was exposed. In Part I, occlusion of the left main coronary artery and hence, myocardial ischemia-induced arrhythmias were achieved by tightening a previously placed loose silk ligature for 30 min. In Part II, arrhythmias were induced by reperfusion following a 20-min ligation of the left main coronary artery. In Part I, early intravenous infusion of nicorandil (100 microg/kg bolus + 10 microg/kg per min) or bimakalim (3 microg/kg bolus + 0.1 microg/kg per min) just prior to and during ischemia increased survival rate (75% and 67% vs. 60% in the control group), significantly decreased the incidence and severity of life-threatening arrhythmias and significantly decreased myocardial infarct size. In Part II also, early intervention by intravenous infusion of nicorandil (100 microg/kg bolus + 10 microg/kg per min) or bimakalim (3 microg/kg bolus + 0.1 microg/kg per min) just before and during ischemia increased survival rate (86% and 75% vs. 55% in the control group), significantly decreased the incidence and severity of life-threatening arrhythmias and significantly decreased myocardial infarct size. However, late intravenous administration of nicorandil or bimakalim at the onset and during reperfusion did not increase survival rate nor confer any antiarrhythmic or cardioprotective effects. The antiarrhythmic and cardioprotective effects of both nicorandil and bimakalim were abolished by pretreating the rabbits with 5-hydroxydecanoate (5 mg/kg, i.v. bolus), a selective mitochondrial KATP channel blocker. In conclusion, intervention by intravenous administration of nicorandil and bimakalim (through the activation of mitochondrial KATP channels), increased survival rate and exhibited antiarrhythmic and cardioprotective effects during coronary occlusion and reperfusion in anesthetized rabbits when administered prior to and during coronary occlusion.