亚低温对大鼠局灶性脑缺血时谷氨酸及一氧化氮的影响

目的　观察 3 3℃亚低温对脑缺血及再灌注时细胞外液中谷氨酸的影响 ,以及脑缺血组织一氧化氮的变化。方法　采用栓线法大鼠大脑中动脉再灌注模型 ,检测不同时点谷氨酸及一氧化氮的含量。结果　在脑缺血期间 ,亚低温组不同时点上谷氨酸及一氧化氮水平均明显低于正常体温组。结论　亚低温时对脑缺血的保护作用机制可能与减少兴奋性神经递质谷氨酸及一氧化氮的释放有关。     

黄蜀葵花总黄酮预处理对脑缺血再灌注损伤的保护作用

目的：研究黄蜀葵花总黄酮（total flavone of Abehnoschl manihot，TFA）对脑缺血再灌注损伤的预适应样保护作用。方法：采用间断静脉推注TFA模拟缺血预适应的方法，分别在大鼠和小鼠大呐中动脉栓塞后再灌模型上，观察脑梗死面积及脑组织和血清中的生化指标的变化。结果：在大鼠大脑中动脉栓塞后再灌模型上，模型组大鼠血清中乳酸脱氢酶（LDH）活性、丙二醛（MDA）和前列腺素E2（PGE2）含量较似手术组明显增高，而TFA（160，80，40，20mg．kg^-1）预处理可明显降低血清中LDH活性、MDA和PGE2含量，同时明显增加血清中一氧化氮合酶（NOS）活性和一氧化氮（N0）含量，TFA（160，80,40，20mg．kg^-1）预处理明显减少脑梗死面积；在小鼠大脑中动脉栓塞后再灌模型上，TFA（200，100，50，25mg／kg）预处理也可明垃减少脑梗死面积并可明显降低血清中LDH和神经元特异性烯醇化酶（NSE）活性以及MDA含量，明显增加血清中NO含量。结论：黄蜀葵花总黄酮预处理对大鼠和小鼠脑缺血再灌注损伤具有预适应样的保护作用。     

复方葛根注射液对大鼠局部脑缺血的保护作用及部分机制研究

目的观察复方葛根注射液对大鼠局部脑缺血的保护作用及其作用机制.方法采用大鼠结扎右侧大脑中动脉(Right MiddleCerebral Artery Occlusion,RMCAO)方法造成局灶性脑缺血模型,研究复方葛根注射液在脑缺血中的保护作用.测定脑组织匀浆中的一氧化氮(NO)及一氧化氮合酶(NOS)含量,探讨药物作用机制.结果复方葛根注射液能够明显减轻脑梗死重量,保护神经细胞,降低脑匀浆中NO及NOS含量.结论复方葛根注射液对脑缺血有明显的保护作用,其机制与其降低脑局部的NO及NOS有关.     

一氧化氮合酶抑制剂与脑缺血

随着对一氧化氮、一氧化氮合酶在脑缺血中作用的深入研究，一氧化氮合酶抑制剂也在不断被开发，并成为保护缺血脑损伤的热点研究之一。本文综述了一氧化氮合酶抑制剂尤其是nNOS和iNOS抑制剂在脑缺血损伤中的作用，为缺血性脑损伤疾病的治疗提供新的途径。     

L-精氨酸和氨基胍对实验性脑缺血损伤的影响

目的观察一氧化氮 (nitricoxide ,NO)供体L 精氨酸 (L arginine)和一氧化氮合酶抑制剂氨基胍 (aminoguanidine,AG)对实验性大鼠局灶性脑缺血损伤的治疗作用以及一氧化氮在脑缺血损伤中的作用规律。方法用线栓法建立大鼠大脑中动脉脑缺血 (MCAO)模型后注射L 精氨酸和AG ,研究大鼠脑缺血后脑梗塞体积变化 ;脑组织中NO、丙二醛 (MDA)含量和一氧化氮合酶(NOS)、超氧化物歧化酶 (SOD)活性的变化 ;缺血脑组织病理变化。结果单独给予L 精氨酸或氨基胍均可明显缩小脑梗塞体积 ,明显降低缺血脑组织MDA含量 ,增强SOD活性 ;L 精氨酸还可明显增加缺血脑组织NO含量 ,氨基胍可明显抑制缺血脑组织NOS活性 ;L 精氨酸与氨基胍合用时 ,上述各项指标与缺血组比较无明显变化。结论L 精氨酸与氨基胍分别单独应用 ,对脑缺血性损伤具有治疗作用 ,两药合用则无明显效果     

Toll样受体信号转导通路介导的脑缺血耐受

许多预处理措施均可诱导脑缺血耐受,如短暂的全身或局部脑缺血、缺氧、内毒素、促炎细胞因子、麻醉剂等。耐受可在数分钟内快速形成(快速耐受),亦可在数小时至数天内迅速建立起神经保护状态(延迟耐受)。缺血造成组织细胞损伤,损伤的组织细胞释放一些内源性的激活物激活Toll样受体(Toll-like receptors,TLR s)炎症信号传导通路,诱发炎症反应,加重缺血损伤。在延迟缺血耐受的形成过程中,预处理激活TLR s信号通路,诱发轻微炎症,同时生成一些反馈抑制物(如抗炎细胞因子、诱饵受体和TLR s信号通路抑制剂)抑制随后严重缺血所造成的炎症反应,从而形成延迟耐受;快速耐受的形成可能是由于预处理因素影响了膜的流动性,改变了脂质筏的结构从而抑制了TLRs炎症信号通路。对脑缺血耐受发生机制的理解有助于预防和治疗脑缺血损伤。     

杜仲提取物预处理对脑缺血再灌注损伤大鼠抗氧化能力及一氧化氮的影响

目的观察杜仲提取物预处理对大鼠脑缺血再灌注损伤中抗氧化能力及一氧化氮的影响,探讨杜仲提取物抗脑缺血再灌注损伤的作用机制。方法雄性SD大鼠120只,随机分为假手术组、模型组、尼莫地平预处理(12 mg·kg~(-1))组和杜仲提取物不同剂量预处理(分别给予200、400、800 mg·kg~(-1)·d~(-1))组,均n=20。各给药组均在制模前预先灌胃给药14 d,采用线栓法制备大鼠局灶性脑缺血再灌注损伤模型,假手术组只分离血管,不留置线栓,假手术及模型组分别给予同体积蒸馏水。缺血2 h再灌注24 h后,用2,3,5-氯化三苯基四氮唑(TTC)染色测定梗死面积,HE染色观察病理形态改变,检测血清及脑组织中丙二醛(MDA)、超氧化物歧化酶(SOD)、一氧化氮(NO)含量及诱导型一氧化氮合酶(iNOS)活性。结果与模型组相比,杜仲提取物各剂量组大鼠脑梗死面积减少(P<0.05)。杜仲提取物中、高剂量组血清和脑组织中的MDA和NO含量及iNOS活性均显著降低,SOD活性显著升高(P<0.05),与尼莫地平组相比无显著差异(P>0.05)。结论杜仲提取物预处理减轻脑缺血再灌注损伤的机制可能是提高抗氧化能力并降低NO水平。     

蝙蝠葛酚性碱对脑缺血大鼠细胞凋亡相关蛋白c—fos表达的影响

目的：探讨蝙蝠葛酚性碱预处理对脑缺血后大脑皮质细胞凋亡相关蛋白c—fos表达的影响。方法：采用线栓阻塞大脑中动脉方法制备大鼠脑缺血模型,并用受试药物术前连续预处理模型大鼠7d。采用免疫组织化学方法测定假手术组、模型组和蝙蝠葛酚性碱高、中、低剂量、尼莫地平、银杏叶片预处理组大鼠缺血后24,48,72h大脑皮质中细胞凋亡相关蛋白c—fos表达变化。结果：行大脑中动脉闭塞后大鼠大脑皮质c—fos均被诱导表达,蝙蝠葛酚性碱预处理7d后,缺血后各时间点大鼠大脑皮质c—fos表达明显下调。结论：蝙蝠葛酚性碱能明显抑制缺血脑损伤后促细胞凋亡蛋白c—fos表达水平,从而在缺血性脑损伤中起到神经保护作用。     

一氧化氮与光化学法诱导大鼠脑缺血早期损伤的关系和绞股蓝总皂苷对脑缺血损伤的保护作用

目的：探讨一氧化氮(NO)与光化学法诱导大鼠脑缺血早期损伤的关系和绞股蓝总皂苷(Gyp)对脑缺血损伤的保护作用。方法：应用光化学法诱导大鼠大脑中动脉栓塞(MCAO)模型，观察氧合血红蛋白(OHb)和Gyp对MCAO后脑梗死范围，脑组织含水量、NO及超氧化歧化酶(SOD)、脂质过氧化产物TBARS含量的影响。结果：MCAO6h可导致大鼠局部脑组织明显梗死、脑水肿，同时SOD活力下降，TBARS含量升高，NO释放减少。OHb能进一步强化上述改变而Gyp能逆转上述变化。结论：脑内过氧化反应水平增高导致早期NO含量减少是脑缺血形成的重要原因之一，Gyp可通过影响脑缺血损伤早期脑内NO水平发挥对脑缺血的保护作用。     

后适应对大鼠脑缺血神经细胞凋亡和内皮型一氧化氮合酶与诱导型一氧化氮合酶的影响

目的：研究缺血耐受（后适应和预适应）对脑缺血再灌注神经细胞凋亡及内皮型一氧化氮合酶（eNOS）和诱导型一氧化氮合酶（iNOS）蛋白表达的影响。方法：50只雄性SD大鼠随机分为假手术组（sham）、脑缺血再灌注模型组（MCAO）、预适应组（MCAO＋preconditioning）、后适应组（MCAO＋postconditioning）和尼莫地平组（MCAO＋nimodipine），每组10只大鼠。预适应组大鼠在MCAO前24h，双侧颈总动脉夹闭2min，再灌注20min，循环两次。后适应组大鼠在脑缺血再灌注开始时，再灌注20s，栓塞20s，循环3次。大鼠大脑中动脉阻断1．5h，再灌注24h。用TUNEL法和免疫组化染色法分别检测缺血半暗带凋亡细胞和iNOS、eNOS蛋白表达。结果：与MCAO组比较，后适应组大鼠脑缺血半暗带的凋亡细胞显著减少，eNOS蛋白表达显著增加，iNOS蛋白表达显著减少，差异有统计学意义（P〈0．05）。结论：缺血后适应能诱导脑缺血耐受，对脑缺血／再灌注损伤产生保护作用，其保护作用与促进eNOS蛋白的表达，抑制iNOS蛋白的表达有关。     

Down regulation of cyclooxygenase-2 is involved in delayed neuroprotection by ischemic preconditioning in rats

Aim: To examine whether the prostaglandins (PGs) pathway is involved in triggering delayed neuroprotection by ischemic preconditioning (IPC) and evaluate the effects of IPC on cyclooxygenase-2 (COX-2) expression following focal cerebral ischemia and reperfusion in rats. Methods: IPC was induced by 10min of saline infusion into the left internal carotid artery with the right common carotid artery clamped at the same time. Middle cerebral artery occlusion (MCAO) and reperfusion model was prodt:ced using intraluminal filament method. Results: IPC 48h priorto MCAO significantly reduced infarct area as compared with MCAO alone. A nonselective inhibitor of COX indomethacin (3mg/kg ip) applied 1h prior to or 1h after IPC failed to affect its protective effects. IPC had no direct effect on the cortex COX-2 mRNA and protein expression 72h later, but decreased the expression of COX-2 mRNA and protein following ischemia and reperfusion insult. Conclusion: PGs pathways was not involved in triggering delayed neuroprotection by IPC, and IPC induced down-regulation of COX-2 following focal cerebral ischemia and reperfusion in rats in vivo.     

Combined pharmacological preconditioning with a G-protein-coupled receptor agonist,a mitochondrial KATP channel opener and a nitric oxide donor mimics ischaemic preconditioning

1. Although pharmacological preconditioning (PPC) has emerged as an alternative to ischaemic preconditioning (IPC) in cardioprotection, the efficacy of PPC compared with IPC has not been investigated. Because IPC is mediated by complex signalling cascades arising from multiple triggers, we have hypothesized that combined PPC is necessary to mimic IPC. 2. Isolated and perfused rat hearts underwent IPC by three cycles of 5 min ischaemia and 5 min reperfusion before 30 min global ischaemia followed by 120 min reperfusion. Adenosine (30 micromol/L), diazoxide (50 micromol/L) and s-nitroso-N-acetylpenicillamine (SNAP; 50 micromol/L) were added for 25 min just before (pretreatment modality) or 45 min before (PPC modality) the index ischaemia. 3. Ischaemic preconditioning significantly improved isovolumic left ventricular (LV) function and reduced infarct size. Although pretreatment with adenosine, diazoxide or SNAP alone was capable of reducing infarct size, PPC with each drug alone or in a combination of two drugs except for diazoxide plus SNAP failed to reduce infarct size. In contrast, PPC in combination with adenosine, diazoxide and SNAP (triple combination PPC) conferred significant improvement of LV function and reduction of infarct size that was as effective as IPC. 4. Cardioprotection afforded by triple combination PPC was abolished by the Gi/o-protein inhibitor pertussis toxin, the mitochondiral KATP channel inhibitor 5-hydroxydecanoate or the nitric oxide (NO) scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethyl imidazoline-1-oxyl 3-oxide (carboxy-PTIO). 5. Protein kinase C (PKC)-epsilon in the particulate fraction was activated throughout preconditioning ischaemia and reperfusion. Although PKC-epsilon was activated during treatment with adenosine, diazoxide or SNAP alone, it was inactivated after washout. In contrast, PKC-epsilon remained activated after triple combination PPC. The PKC inhibitor chelerythrine abolished activation of PKC-epsilon and cardioprotection afforded by IPC and triple combination PPC. 6. These results demonstrate that combined PPC with a G-protein-coupled receptor agonist, a mitochondrial KATP channel opener and an NO donor is necessary to mimic IPC and such synergistic cardioprotection is associated with enhanced and sustained activation of PKC-epsilon.     

Intravenous adenosine protects the myocardium primarily by activation of a neurogenic pathway

Endogenous adenosine is a trigger for ischemic myocardial preconditioning (IPC). Although intravascular administration of adenosine has been used to further unravel the mechanism of protection by IPC, it is questionable whether adenosine and IPC employ the same signaling pathways to exert cardioprotection. We therefore investigated whether the active metabolic barrier of the endothelium prevents an increase in myocardial interstitial adenosine concentrations by intravenous adenosine, using microdialysis, and also the role of NO and activation of a neurogenic pathway in the cardioprotection by adenosine. In pentobarbital-anesthetized rats, area at risk and infarct size (IS) were determined 120 min after a 60-min coronary artery occlusion (CAO), using trypan blue and nitro-blue-tetrazolium staining, respectively. IPC with a single 15-min CAO and a 15-min adenosine infusion (ADO, 200 microg min(-1) i.v.) limited IS to the same extent (IS = 41 +/- 6% and IS = 40 +/- 4%, respectively) compared to control rats (IS = 63 +/- 3%, both P < 0.05). However, IPC increased myocardial interstitial adenosine levels seven-fold from 4.3 +/- 0.7 to 27.1 +/- 10.0 microM (P < 0.05), while ADO had no effect on interstitial adenosine (4.1 +/- 1.2 microM), or any of the other purines. The NO synthase inhibitor N(omega)-nitro-L-arginine (LNNA), which did not affect IS (IS = 62 +/- 3%), attenuated the protection by ADO (IS = 56 +/- 3%; P < 0.05 vs ADO, P = NS vs LNNA). The ganglion blocker hexamethonium, which had also no effect on IS (IS = 66 +/- 3%), blunted the protection by ADO (IS = 55 +/- 4%; P < 0.05 vs ADO and vs hexamethonium). These observations demonstrate that cardioprotection by ADO is dependent on NO, and is primarily mediated by activation of a neurogenic pathway.     

桂枝汤有效部位A对IL-1刺激的大鼠脑微血管内皮细胞前列腺素E2及其主要信号转导元件的影响

目的：探讨桂枝汤解热有效部位A(Fr．A)对IL-1刺激的大鼠脑微血管内皮细胞(rCMEC)PGE，信号转导通路主要元件的影响。方法：制备大鼠含药血清，通过放射免疫法测定PGE2含量，酶反应底物法测定PLA，活性，ELISA法测定COX活性，比色法测定NO含量。结果：Fr．A含药血清处理rCMEC后，在IL-1刺激下，孵育液中PGE2和NO含量、总COX和COX-2活性均显著减低，对升高的sPLA2活性无明显影响。结论：Fr．A可通过影响PGE2信号转导通路主要元件COX及NO，进而影响PGE2水平。     

一氧化氮在缺血性脑损伤中作用的实验研究进展

一氧化氮 (NO)在缺血性脑损伤中具有双重作用 ,既表现为神经保护作用 ,又有神经毒性作用。在脑缺血过程中 ,源于内皮型一氧化氮合酶 (eNOS)产生的NO有神经保护作用 ,源于神经元型一氧化氮合酶 (nNOS)和诱导型一氧化氮合酶 (iNOS)过度表达所形成的NO有神经毒性作用。利用NO的双重作用 ,找到防治脑缺血的药物及给药时间和剂量等一直是研究的热点。     

Pharmacological preconditioning by levosimendan is mediated by inducible nitric oxide synthase and mitochondrial KATP channel activation in the in vivo anesthetized rabbit heart model

BACKGROUND: Provocation of fatal cardiac arrhythmias has limited the use of inotropic agents as heart failure therapy. Levosimendan (LEV) is a new inodilator, whose mechanism of action includes calcium sensitization of contractile proteins and the opening of ATP-dependent potassium channels. OBJECTIVES AND METHODS: The aim of this investigation was to test whether the administration of LEV has cardioprotective and antiarrhythmic effects against ischemia and reperfusion injury in a manner similar to ischemic preconditioning (IPC) in a well-standardized model of reperfusion arrhythmias in anesthetized adult male rabbits (n=122) subjected to 30 min occlusion of the left coronary artery followed by 120 min of reperfusion. RESULTS: Pretreatment with either 1 cycle of IPC, LEV (0.1 micromol/kg, i.v.), or IPC+LEV prior to the period of coronary occlusion offers significant infarct size reduction (21.6+/-1.6%, 22.1+/-2.2%, and 21.4+/-1.4%, respectively vs 38.7+/-3.6% in saline control group; P<0.01) and antiarrhythmic effects. IPC, LEV and IPC+LEV treatment significantly attenuated the incidence of life-threatening arrhythmias like sustained VT (13%, 13% and 13%, respectively vs 100% in saline control group; P<0.005) and other arrhythmias (25%, 25% and 13%, respectively vs 100% in saline control group; P<0.005), and increased the number of surviving animals without arrhythmias. Pretreatment with 5-HD, N(omega)-nitro-L-arginine methyl ester (L-NAME, a nonspecific NOS inhibitor) and the specific iNOS inhibitor 1400 W [N-(-3-(aminomethyl)benzyl) acetamidine] abolished the beneficial effects of IPC, and LEV on reperfusion induced arrhythmias and cardioprotection suggesting that benefits have been achieved via both the selective activation of cardiomyocyte mitochondrial K(ATP) channels and NO. One cycle of IPC and LEV pretreatment significantly preserved the level of ATP in the 30 min ischemic heart and 120 min reperfused heart. CONCLUSIONS: The present study demonstrates similarities between acute LEV treatment and IPC of the rabbit myocardium in terms of survival, cardioprotection, antiarrhythmic activity, and metabolic status.     

多发性脑梗死患者血浆内皮素和一氧化氮含量变化及意义

目的:观察多发性脑梗死后患者血浆内皮素(ET)和一氧化氮(NO)含量变化及意义。方法:用放射免疫法、硝酸还原法检测30例多发性脑梗死患者血浆ET、NO含量变化,并与30例单发性脑梗死、30例健康人血浆ET、NO含量作对照分析。结果:多发性脑梗死后6h、24h、3d及7d血浆ET、NO浓度较对照组明显升高,差异有显著性意义(P<0.001);多发性ET、NO浓度高于单发性(ET:98.85±13.1,83.50±11.2;NO:85.62±11.52,81.50±10.68),两者比较,P<0.05。结论:ET、NO均参与了脑梗死病理生理过程,ET、NO浓度变化可作为脑梗死临床治疗、判断预后的实验性指标之一。     

甘西鼠尾草注射液与丹参注射液对大鼠缺血再灌注损伤保护作用的比较

目的:比较甘西鼠尾草注射液与丹参注射液对大鼠缺血再灌注损伤的保护作用。方法:采用改良线栓法阻断大鼠大脑中动脉,建立脑缺血模型,到达再灌注时限后进行神经功能缺损评分,用试剂盒检测脑组织中NOS、NO含量,并计算脑组织含水量判定脑水肿情况;通过结扎双侧颈总动脉,考察两药对脑血管通透性的影响。结果:甘西鼠尾草注射液与丹参注射液均可改善缺血再灌注损伤大鼠神经功能缺损;降低脑组织中NOS、NO含量;降低脑血管通透性;对脑水肿也有一定的缓解作用。结论:甘西鼠尾草注射液与丹参注射液对大鼠缺血再灌注损伤均有保护作用,小剂量丹参注射液在降低脑水肿和神经功能缺损评分方面优于小剂量甘西鼠尾草注射液;大剂量甘西鼠尾草注射液在降低脑血管通透性方面优于等剂量的丹参注射液。