5-脂氧合酶（5-LOX）及代谢产物在异氟醚预处理脑保护作用中的研究进展

缺血性脑血管疾病（Ischemia Cerebral Vascular Disease,ICVD）可造成不同程度的神经功能障碍,以其高发病率、高致残率、高复发率、高死亡率严重威胁着人们的身体健康。而脑组织缺血后再灌注损伤即脑缺血再灌注损伤（ischemia-reperfusion injury）是脑缺血性疾病的最主要的损伤原因之一,因此阐明脑缺血再灌注损伤发生发展的病理生理机制、探寻有效的预防保护措施成为当今研究的重点问题。本文回顾、归纳脑缺血再灌注损伤的相关分子机制及异氟醚预处理对脑缺血再灌注损伤的保护作用,分析5-脂氧合酶及其代谢产物在脑缺血再灌注损伤中的作用及其与其他分子的相互关系,旨在探讨5-脂氧合酶及其代谢产物在异氟醚预处理保护脑缺血再灌注损伤中可能起到的作用。为脑缺血再灌注损伤的防治提供更多的理论依据。     

芪蝎活血通络汤对局灶性脑缺血再灌注损伤模型大鼠神经功能、氧化应激及炎症因子的影响

目的:探讨芪蝎活血通络汤对局灶性脑缺血再灌注损伤模型大鼠神经功能、氧化应激及炎症因子的影响。方法:50只SD大鼠随机选取40只采用线栓法构建脑缺血再灌注模型,其中36只成功,4只死亡。随机数字表法将36只脑缺血再灌注模型大鼠分为模型组、低剂量组(芪蝎活血通络汤2.0 mg/kg灌胃处理)、中剂量组(芪蝎活血通络汤4.0 mg/kg灌胃处理)和高剂量组(芪蝎活血通络汤8.0 mg/kg灌胃处理),每组9只,剩余10只大鼠仅切开皮肤分离和夹闭血管(对照组)。建模后芪蝎活血通络汤各剂量组给予相应剂量灌胃,对照组和模型组给予同剂量生理盐水灌胃,持续4周。用药4周后测评各组大鼠神经功能缺损程度、双侧贴纸去除时间、平衡木过杆时间,并测定各组大鼠脑组织中含水量、脑梗死面积以及氧化应激[过氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)、过氧化氢酶(CAT)、丙二醛(MDA)]和炎症因子[白细胞介素-1β(IL-1β),白细胞介素-6(IL-6),肿瘤坏死因子-α(TNF-α)]指标。结果:与对照组比较,模型组大鼠m NSS评分、脑组织含水量、MDA含量、IL-6、IL-1β、TNF-α水平升高(P<0.05),双侧贴纸去除时间、平衡木过杆时间延长(P<0.05),脑梗死面积增大(P<0.05),SOD、GSH-Px、CAT活性降低(P<0.05);与模型组比较,芪蝎活血通络汤各剂量组大鼠m NSS评分、脑组织含水量、MDA含量、IL-6、IL-1β、TNF-α水平降低(P<0.05),双侧贴纸去除时间、平衡木过杆时间缩短(P<0.05),脑梗死面积缩小(P<0.05),SOD、GSH-Px、CAT活性升高(P<0.05);与低剂量组比较,中、高剂量组大鼠m NSS评分降低(P<0.05),双侧贴纸去除时间、平衡木过杆时间缩短(P<0.05);高剂量组大鼠脑梗死面积、脑组织MDA、IL-6、IL-1β、TNF-α低于低剂量组(P<0.05),SOD、GSH-Px、CAT高于低剂量组(P<0.05)。结论:芪蝎活血通络汤可降低大鼠脑缺血再灌注损伤,改善神经功能,其治疗作用可能与抗氧化,抗炎作用有关,8.0 mg/kg剂量效果最显著。     

淫羊藿苷缓解腹部皮瓣缺血再灌注损伤模型大鼠的作用及机制研究

摘要 目的：研究淫羊藿苷缓解腹部皮瓣缺血再灌注损伤（IRI）模型大鼠的作用及机制。方法：取30只SD级大鼠作为研究对象,将其按照随机数字表法分作假手术组、模型组以及淫羊藿苷组,每组各10只。其中模型组和淫羊藿苷组大鼠均制作大鼠腹部皮瓣IRI模型,假手术组以及模型组大鼠予以生理盐水腹腔注射,淫羊藿苷组大鼠则予以淫羊藿苷腹腔注射。对比各组大鼠皮瓣存活面积及存活率、血清炎症因子以及氧化应激指标水平、皮瓣组织中p38丝裂原活化蛋白激酶（p38 MAPK）信号通路相关蛋白表达情况。结果：模型组、淫羊藿苷组大鼠的皮瓣存活面积及存活率均低于假手术组,但淫羊藿苷组大鼠的皮瓣存活面积及存活率均高于模型组（P＜0.05）。模型组、淫羊藿苷组大鼠血清白细胞介素-10（IL-10）均低于假手术组,但淫羊藿苷组高于模型组;模型组、淫羊藿苷组大鼠血清肿瘤坏死因子-?琢（TNF-?琢）均高于假手术组,但淫羊藿苷组低于模型组（P＜0.05）。模型组、淫羊藿苷组大鼠血清超氧化物歧化酶（SOD）、谷胱甘肽（GSH）水平均低于假手术组,但淫羊藿苷组大鼠血清SOD、GSH水平均高于模型组;模型组、淫羊藿苷组大鼠血清丙二醛（MDA）水平均高于假手术组,但淫羊藿苷组大鼠血清MDA水平低于模型组（P＜0.05）。模型组、淫羊藿苷组大鼠皮瓣组织p38 MAPK、丝裂原活化蛋白激酶磷酸酶-2（MKP-2）相对表达量均高于假手术组,但淫羊藿苷组皮瓣组织p38 MAPK相对表达量低于模型组,而MKP-2相对表达量高于模型组（P＜0.05）。结论：淫羊藿苷可通过调控p38 MAPK信号通路缓解炎症反应及氧化应激,发挥减轻腹部皮瓣IRI的作用。     

用于脑缺血小鼠海马SOD1表达的改进灌注固定法

常规灌注固定法多用于兔和大鼠等较大动物,并存在一些不足。改进了灌注固定法流程、灌注溶液的配方、流速、用量以及灌注装置,将其用于在显微操作下制备的缺血再灌注C57BL/6N小鼠模型,并对其海马进行H.E染色和免疫组织化学SOD1基因表达。结果显示,改进的灌注固定法使组织切片结构更加清晰,海马免疫阳性神经元定位于胞浆。缺血再灌注组(24hI/R)海马神经元SOD1表达比假手术对照组(sham-o)减少,而高压氧治疗组(24hHBO)SOD1表达有所恢复。表明改进的灌注固定法用于缺血再灌注C57BL/6N小鼠海马SOD1基因表达效果良好,结果可靠。实验结果提示,高压氧的治疗机制之一可能是通过增加SOD1基因表达而实现的。     

Ischemic preconditioning ameliorates microcirculatory disturbance through downregulation of TNF-alpha production in a rat cremaster muscle model

Ischemia-reperfusion (I/R) injury is a complex process involving the generation and release of inflammatory cytokines, and the accumulation and infiltration of neutrophils and macrophages, which disturbs the microcirculatory hemodynamics. Nonetheless, ischemic preconditioning (IPC) is known to produce immediate tolerance to subsequent prolonged I/R insults, although its underlying mechanism largely remains unknown. Our study investigated the role of the IB--NF-B-TNF- (tumor necrosis factor-) pathway in IPC's ability to ameliorate I/R-induced microcirculatory disturbances in rat cremaster muscle flaps. Male Sprague-Dawley rats were randomized (n=8 per group) into 3 groups: a sham-operated control group, an I/R group (4 h of pudic epigastric artery ischemia followed by 2 h of reperfusion), and an IPC+I/R group (3 cycles of 10 min of ischemia followed by 10 min reperfusion before I/R). Intravital microscopy was used to observe leukocyte/endothelial cell interactions and quantify functional capillaries in cremaster muscles. I/R markedly increased the number of rolling, adhering, and migrating leukocytes. It was also observed that I/R significantly increased TNF- expression in these injured tissues. On the other hand, IPC prevented I/R-induced increases in leukocyte rolling, adhesion, and transmigration. Moreover, TNF- protein production and its mRNA expression were downregulated in the IPC group. Finally, I/R-induced IB- phosphorylation and NF-B (p65) nuclear translocation were both suppressed by IPC. These results indicated that IPC attenuated NF-B activation and subsequently reduced TNF- expression, which resulted in the amelioration of microcirculatory disturbances in I/R-injured cremaster muscles.     

Role of apoptosis-inducing factor in myocardial cell death by ischemia-reperfusion

Although apoptosis contributes to myocardial cell death in the ischemia-reperfused heart, the molecular basis of apoptosis is poorly understood. Apoptosis-inducing factor (AIF) has been characterized as a caspase-independent death effector. Upon the induction of apoptosis, mitochondrial AIF is released to the cytoplasm and then enters the nucleus, in which it induces chromatin condensation and 50 kbp DNA fragmentation. In the present study, we examined the role of AIF in ischemia-reperfusion injury in isolated rat hearts. AIF was detected in the cytosolic and nuclear fractions of hearts subjected to ischemia-reperfusion, whereas it was detected only in the mitochondria of control hearts. Moreover, AIF release increased in a reperfusion time-dependent manner. Pulse field gel electrophoresis revealed that 50 kbp DNA fragments were produced by ischemia/reperfusion. In contrast, cytochrome c release and the activation of caspase-3 did not occur to a significant extent. Moreover, ischemic preconditioning attenuated the AIF release and the 50 kbp DNA fragmentation. These results suggest that AIF-dependent apoptosis is likely to attribute to myocardial cell death in the ischemia-reperfused heart and that it is related with the protective effect of ischemic preconditioning.     

Myocardial protection of MCI-186 in rabbit ischemia-reperfusion

We observed that 3-methyl-1-1phenyl-2-pyrazolin-5-one (MCI-186), a newly-developed free radical scavenger, attenuated necrosis in the in vivo rabbit hearts upon reperfusion after prolonged ischemia. In rabbits undergoing 1 hour ligation of the anterior ventricular coronary artery, a single bolus injection of MCI-186 (1.5 mg/kg) was introduced into the post-ischemic heart immediately before 4 hour reperfusion. Compared to negligible necrosis in sham-operated control animals and 33.81 +/- 13.50% necrosis in the area at risk for the saline control group (n = 8), the MCI-186 - treated group (n = 8) had a necrosis of 13.27 +/- 4.60% (p < 0.05 vs saline control group). The pressure-rate index had a slight decrease in MCI-186 treated group compared to the control group (p > 0.05). However, the blood levels of malondialdehyde (MDA) in MCI-186 treated group (2.08 +/- 0.23 microM) was significantly smaller than that of 2.65 +/- 0.31 microM in control animals (p < 0.01), while sham control had an average MDA level of 1.91 +/- 0.40 microM, with p > 0.05 relative to that in the MCI-186 treated group. These data support our contention that MCI-186 reduces reperfusion injury in perfused hearts with prolonged ischemia and the mechanism for the in vivo efficacy of MCI-186 is predominantly related to its antioxidant activities.     

Brief exposure to carbon monoxide preconditions cardiomyogenic cells against apoptosis in ischemia-reperfusion

We examined whether and how pretreatment with carbon monoxide (CO) prevents apoptosis of cardioblastic H9c2 cells in ischemia-reperfusion. Reperfusion (6 h) following brief ischemia (10 min) induced cytochrome c release, activation of caspase-9 and caspase-3, and apoptotic nuclear condensation. Brief CO pretreatment (10 min) or a caspase-9 inhibitor (Z-LEHD-FMK) attenuated these apoptotic changes. Ischemia-reperfusion increased phosphorylation of Akt at Ser472/473/474, and this was enhanced by CO pretreatment. A specific Akt inhibitor (API-2) blunted the anti-apoptotic effects of CO in reperfusion. In normoxic cells, CO enhanced generation, which was inhibited by a mitochondrial complex III inhibitor (antimycin A) but not by a NADH oxidase inhibitor (apocynin). The CO-enhanced Akt phosphorylation was suppressed by an scavenger (Tiron), catalase or a superoxide dismutase (SOD) inhibitor (DETC). These results suggest that CO pretreatment induces mitochondrial generation of , which is then converted by SOD to H₂O₂, and subsequent Akt activation by H₂O₂ attenuates apoptosis in ischemia-reperfusion.     

Beneficial effect of preconditioning on ischemia-reperfusion injury in the rat bladder in vivo

We investigated the effect of preconditioning on ischemia-reperfusion injury in the rat bladder. Rat abdominal aorta was clamped with a small clip to induce ischemia-reperfusion injury in the bladder. Twelve-week-old male SD rats were divided into three groups; sham-operated control (Cont), 30 min ischemia-60 min reperfusion (IR) and three times of 5 min ischemia and then 30 min ischemia-60 min reperfusion (PC) groups. The bladder functions were estimated by cystometric and functional studies. Contractile response curves to increasing concentrations of carbachol were constructed in the absence and presence of various concentrations of subtype selective muscarinic antagonists, i.e. atropine (non-selective), pirenzepine (M1 selective), methoctramine (M2 selective), and 4-DAMP (M1/M3 selective). We also measured tissue levels of malonaldehyde (MDA) and examined possible histological changes in these rats' bladders. Preconditioning partially prevented the reduction of bladder dysfunction induced by ischemia-reperfusion. Estimation of the pA2 values for atropine, pirenzepine, methoctramine, and 4-DAMP indicates that the carbachol-induced contractile response in bladder dome is mediated through the M3 receptor subtype in all groups. The MDA concentration in the IR group was significantly larger than that of the control group, and preconditioning significantly reduced MDA production in the bladder. In histological studies, the ischemia-reperfusion with or without preconditioning caused infiltration of leukocytes and rupture of microcirculation in the regions of submucosa and smooth muscle without a corresponding sloughing of mucosal cells. Our data indicate that preconditioning has a beneficial effect on ischemia-reperfusion injury in the rat bladder.