注射用尼莫地平脂质体对大鼠局灶性脑缺血再灌注损伤的影响

目的:探讨注射用尼莫地平脂质体对大鼠局灶性脑缺血再灌注损伤的影响.方法:70只SD大鼠分为注射用尼莫地平脂质体(nimodipine liposomes for injection,NDLI)1.00mg/kg组、NDLI 0.50mg/kg组、NDLI 0.25mg/kg组、尼莫地平组(1.00 mg/kg)、溶媒组(10 mL/Kg)、假手术组和缺血模型组.复制大鼠大脑中动脉闭塞模型.对各组大鼠进行行为学评分,检测梗死灶体积、脑含水量、脑匀浆生化指标和脑组织学.结果:NDLI 1.00 mg/kg、0.50 mg/kg和0.25 mg/kg均能够显著改善局灶性脑缺血大鼠的行为学评分,缩小梗死灶体积,减少脑含水量,提高脑组织内Na+,K+-ATP酶、Ca2+-ATP酶、谷胱甘肽和超氧化物歧化酶活性,降低丙二醛、乳酸和一氧化氮含量,并能改善脑组织损伤.结论:NDLI对大鼠局灶性脑缺血再灌注损伤有保护作用.     

The role of mineralocorticoid receptor expression in brain remodeling after cerebral ischemia

Mineralocorticoid receptors (MRs) are classically known to be expressed in the distal collecting duct of the kidney. Recently it was reported that MR is identified in the heart and vasculature. Although MR expression is also found in the brain, it is restricted to the hippocampus and cerebral cortex under normal condition, and the role played by MRs in brain remodeling after cerebral ischemia remains unclear. In the present study, we used the mouse 20-min middle cerebral artery occlusion model to examine the time course of MR expression and activity in the ischemic brain. We found that MR-positive cells remarkably increased in the ischemic striatum, in which MR expression is not observed under normal conditions, during the acute and, especially, subacute phases after stroke and that the majority of MR-expressing cells were astrocytes that migrated to the ischemic core. Treatment with the MR antagonist spironolactone markedly suppressed superoxide production within the infarct area during this period. Quantitative real-time RT-PCR revealed that spironolactone stimulated the expression of neuroprotective or angiogenic factors, such as basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF), whereas immunohistochemical analysis showed astrocytes to be cells expressing bFGF and VEGF. Thereby the incidence of apoptosis was reduced. The up-regulated bFGF and VEGF expression also appeared to promote endogenous angiogenesis and blood flow within the infarct area and to increase the number of neuroblasts migrating toward the ischemic striatum. By these beneficial effects, the infarct volume was significantly reduced in spironolactone-treated mice. Spironolactone may thus provide therapeutic neuroprotective effects in the ischemic brain after stroke.     

小鼠诱导型环氧化酶基因敲除对脑缺血损伤的保护作用

目的　观察敲除诱导型环氧化酶 (cyclooxygenase ,COX2 )基因对小鼠脑缺血再灌注后脑梗死体积、前列腺素E2(prostaglandinE2 ,PGE2 )含量的影响。方法　应用COX2基因敲除小鼠 ,制备小鼠短暂性局灶脑缺血模型 ;采用TTC染色及计算机图像分析测定脑梗死体积 ;应用ELISA方法测定PGE2 含量。结果　COX2基因完全敲除鼠的脑梗死体积显著小于杂合子组和未敲除COX2基因组 ,而杂合子组脑梗死体积与未敲除COX2基因组相比无显著差异。COX2基因完全敲除鼠缺血 1h再灌注 2 4h后 ,PGE2 含量与杂合子组和未敲除COX2基因组相比显著降低 ,而杂合子组PGE2 含量与未敲除COX2基因组相比无显著差异。结论　COX2参与了脑缺血再灌注损伤 ,敲除COX2基因对脑缺血再灌注损伤具有保护作用     

参芪宜脑胶囊对实验性脑缺血大鼠的保护作用

目的观察参芪宜脑胶囊对缺血性脑水肿及超氧化物歧化酶(SOD)活力的影响,探讨其对实验性脑缺血大鼠的保护作用。方法分别以参芪宜脑胶囊小剂量(0.8g/kg)、中剂量(1.6g/kg)、大剂量(3.2g/kg)对大鼠进行灌胃给药,并结扎大鼠双侧颈总动脉,形成急性实验性不完全性脑缺血模型,3h后断头取脑,检测脑含水量和SOD活力。结果参芪宜脑胶囊小、中剂量组脑水含量分别为(3.62±0.10)mL/g·dw与(3.64±0.09)mL/g·dw明显低于缺血模型组的(3.79±0.14)mL/g·dw(P<0.01);而SOD活力分别为(119.18±17.69)nU/mg·prot和(120.24±14.53)nU/mg·prot,明显高于模型组的(95.39±9.21)nU/mg·prot(P<0.01)。结论参芪宜脑胶囊可减轻缺血性脑水肿和超氧化损伤,对缺血性脑损伤有一定的保护作用。     

Mangiferin exerts neuroprotective effects against focal cerebral ischemia in mice by regulating NF-κB signaling pathway

Purpose: Mangiferin is a natural free radical scavenging antioxidant that induces excitation of the central nervous system. However, the mechanism of neuroprotective effect of mangiferin on focal cerebral ischemia has not been fully investigated. The aim of this study was to investigate the protective effect of mangiferin on focal cerebral ischemia in mice.

Methods: Middle cerebral artery occlusion (MCAO) was performed to investigate the effect of mangiferin on focal cerebral ischemia. Mice were randomly divided into 5 groups: sham, MCAO, MCAO?+?5 mg/kg mangiferin, MCAO?+?20 mg/kg mangiferin and MCAO?+?5 mg/kg nimodipine. Neurobehavioral scores, brain edema, brain injury scores, relative infarct size and expression of some inflammatory factors in the brain were evaluated. NF-κB pathway was detected by Western blotting and immunofluorescence.

Results: The results showed that mangiferin effectively attenuated MCAO-induced brain injury, including improvement of neurological impairment, reduction of brain edema, and reduction of infarct size. Compared with the MCAO group, mangiferin significantly inhibited MCAO-induced neuroinflammation, which can be proved by reduced expression levels of TNF-α, IL-1β, iNOS and COX-2. In addition, we found that phosphorylation of IκBα was inhibited and the expression of NF-κB p65 in the nucleus was reduced after the addition of mangiferin.

Conclusion: Our study suggested that mangiferin exerts neuroprotective effects on focal cerebral ischemia in mice by regulating the NF-κB signaling pathway. Mangiferin may be an effective treatment for cerebral ischemia and other neurological disorders.

     

Constitutive overexpression of Cu/Zn superoxide dismutase exacerbates kainic acid-induced apoptosis of transgenic-Cu/Zn superoxide dismutase neurons.

Cu/Zn superoxide dismutase (Cu/Zn SOD) is a key enzyme in the metabolism of oxygen free radicals. The gene resides on chromosome 21 and is overexpressed in patients with Down syndrome. Cultured neurons of transgenic Cu/Zn SOD (Tg-Cu/Zn SOD) mice with elevated activity of Cu/Zn SOD were used to determine whether constitutive overexpression of Cu/Zn SOD creates an indigenous oxidative stress that predisposes the Tg-Cu/Zn SOD neurons to added insults. Neurons from three independently derived Tg-Cu/Zn SOD strains showed higher susceptibility than nontransgenic neurons to kainic acid (KA)-mediated excitotoxicity, reflected by an earlier onset and enhanced apoptotic cell death. This higher susceptibility of transgenic neurons to KA-mediated apoptosis was associated with a chronic prooxidant state that was manifested by reduced levels of cellular glutathione and altered [Ca2+]i homeostasis. The data are compatible with the thesis that overexpression of Cu/Zn SOD creates chronic oxidative stress in the transgenic neurons, which exacerbates their susceptibility to additional insults such as KA-mediated excitotoxicity.     

Pathophysiology of superoxide radical as potential mediator of reperfusion injury in pig heart

Summary The role of oxygen0derived free radicals in myocardial reperfusion injury was studied using the isolated in situ pig heart model. The free radical scavengers, superoxide dismutase (SOD) and catalase, protected the ischemic pig heart subjected to one hour of normothermic regional ischemia followed by one hour of global hypothermic arrest and one hour normothermic reperfusion. A significant increase in thiobarbituric acid reactive material and oxidized glutathione appeared in the perfusate demonstrating free radical-mediated lipid peroxidation during reperfusion, and this was prevented by the addition of SOD plus catalase. The values of three important antioxidative enzymes, SOD, catalase, and glutathione peroxidase, showed reduced activities after 2 hours of ischemia. These values did not change significantly after 60 minutes of reperfusion following the 2 hours ischemic insult. The concentrations of high-energy phosphate compounds including creatine phosphate (CP), adenosine triphosphate (ATP), and total adenine nucleotide were reduced significantly during ischemia and reperfusion in hearts which were not protected by SOD and catalase. The plasma creatine phosphokinase levels were lowered appreciably as a result of SOD and catalase treatment. It may be concluded from these experiments that oxygen-derived free radicals are present during reperfusion and SOD and catalase play a significant role in the protection of ischemic myocardium from reperfusion injury.     

Evidence for a protective role of metallothionein-1 in focal cerebral ischemia

Metallothioneins (MTs) are a family of metal binding proteins that have been proposed to participate in a cellular defense against zinc toxicity and free radicals. In the present study, we investigated whether increased expression of MT in MT-1 isoform-overexpressing transgenic mice (MT-TG) affords protection against mild focal cerebral ischemia and reperfusion. Transient focal ischemia was induced in control (wild type) and MT-TG mice by occluding the right middle cerebral artery for 45 min. Upon reperfusion, cerebral edema slowly developed and peaked at 24 hr as shown by T2-weighted MRI. The volume of affected tissue was on the average 42% smaller in MT-TG mice compared with control mice at 6, 9, 24, and 72 hr and 14 days postreperfusion (P < 0.01). In addition, functional studies showed that 3 weeks after reperfusion MT-TG mice showed a significantly better motor performance compared with control mice (P = 0.011). Although cortical baseline levels of MT-1 mRNA were similar in control and MT-TG mice, there was an increase in MT-1 mRNA levels in the ischemic cortex of MT-TG mice to 7.5 times baseline levels compared with an increase to 2.3 times baseline levels in control mice 24 hr after reperfusion. In addition, MT-TG mice showed an increased MT immunoreactivity in astrocytes, vascular endothelial cells, and neurons 24 hr after reperfusion whereas in control mice MT immunoreactivity was restricted mainly to astrocytes and decreased in the infarcted tissue. These results provide evidence that increased expression of MT-1 protects against focal cerebral ischemia and reperfusion.     

Amlodipine treatment reduces stroke size in apolipoprotein E-deficient mice

BACKGROUND: This study investigated the effects of amlodipine, an L-type calcium channel blocker, on stroke size after focal brain ischemia in apolipoprotein E-deficient (ApoE KO) mice. METHODS: Mice were subjected to middle cerebral artery (MCA) occlusion after being given a high-cholesterol (HCD) or normal diet for 10 weeks with or without amlodipine at a nonhypotensive dose of 3 mg/kg/day. Ischemic brain area was measured by 2,3,5-triphenyltetrazolium chloride staining. Cerebral blood flow was analyzed by laser-Doppler flowmetry. Superoxide anion production in the brain was detected by dihydroethidium staining. RESULTS: The ApoE KO mice given HCD for 10 weeks showed a larger ischemic lesion size than mice with a normal diet. Amlodipine treatment in parallel with HCD feeding reduced the ischemic lesion size in ApoE KO mice. Interestingly, amlodipine treatment for only the last 2 weeks was also effective in reducing the ischemic lesion size in HCD-fed ApoE KO mice. The neurologic deficit after MCA occlusion was also improved by amlodipine treatment for either 10 weeks or 2 weeks. The decrease in surface cerebral blood flow after MCA occlusion was significantly attenuated in the peripheral region of the MCA territory in amlodipine-treated mice. Amlodipine treatment in HCD-fed ApoE KO mice also reduced superoxide production in the ischemic area of the brain. CONCLUSIONS: These results suggest that amlodipine treatment reduces stroke size and neurologic deficit after focal brain ischemia, possibly through an increase in cerebral blood flow and inhibition of superoxide production.     

Overexpression of thioredoxin in transgenic mice attenuates focal ischemic brain damage

Thioredoxin (TRX) plays important biological roles both in intra- and extracellular compartments, including in regulation of various intracellular molecules via thiol redox control. We produced TRX overexpressing mice and confirmed that there were no anatomical and physiological differences between wild-type (WT) mice and TRX transgenic (Tg) mice. In the present study we subjected mice to focal brain ischemia to shed light on the role of TRX in brain ischemic injury. At 24 hr after middle cerebral artery occlusion, infarct areas and volume were significantly smaller in Tg mice than in WT mice. Moreover neurological deficit was ameliorated in Tg mice compared with WT mice. Protein carbonyl content, a marker of cellular protein oxidation, in Tg mice showed less increase than did that of WT mice after the ischemic insult. Furthermore, c-fos expression in Tg mice was stronger than in WT mice 1 hr after ischemia. Our results suggest that transgene expression of TRX decreased ischemic neuronal injury and that TRX and the redox state modified by TRX play a crucial role in brain damage during stroke.     

脑温对大鼠灶性脑缺血再灌注损伤的影响

目的　研究预高温和缺血时轻度高温、亚低温对脑缺血再灌注损伤组织脂质过氧化和缺血脑组织病变的影响。方法　 75只Wistar大鼠按不同脑温和缺血条件被随机分为生化组 (5组 ,n=7) 和病理组 (5组 ,n=8) ,采用Nagasawa脑缺血模型 ,观察脑缺血再灌注损伤组织超氧化物歧化酶 (SOD)、谷胱甘肽过氧化物酶 (GSH Px)、还原型谷胱甘肽 (GSH)、丙二醛 (MDA)及缺血脑组织病理变化。结果　轻度高温加重常温脑缺血组织SOD、GSH的降低和MDA的增高 ,使GSH Px呈降低趋势 ,而亚低温相反 ;预高温对常温脑缺血各项指标影响不显著。轻度高温组脑缺血病理损伤最重 ,亚低温和预高温有改善脑缺血损伤的作用。结论　高温加重而亚低温抑制脑缺血损伤 ,分别与其增加或减少内源性抗氧化酶消耗、降低或增强缺血脑组织清除氧自由基的能力有关 ;预高温对缺血脑组织有保护作用 ,未能肯定此作用与内源性抗氧化酶消耗减少和缺血脑组织清除氧自由基的能力增强有关     

脑缺血再灌注后神经细胞凋亡和细胞色素C基因表达及肌苷的干预作用

目的　研究肌苷对大鼠局灶性脑缺血再灌注后神经细胞凋亡和细胞色素C(CytC)基因表达的影响 ,探讨肌苷的神经保护作用机制。　方法　应用线栓法建立SD大鼠大脑中动脉阻塞(MCAO)再灌注模型 ,腹腔注射肌苷注射液 (10 0mg/kg) ,原位末端标记 (TUNEL)和原位杂交技术分别观察神经细胞凋亡和CytCmRNA表达。　 结果　脑缺血再灌注后 2h皮质区与纹状体区即出现凋亡细胞并逐渐增加 ,皮质区和纹状体区分别于 1d和 2d达高峰 ,之后逐渐减少 ,至 14d接近于假手术组水平 ;经肌苷治疗后凋亡神经细胞减少 ,其中再灌注 12h～ 7d较对照组相应时间点减少明显 ,差异有显著性 (P >0 0 5 )。CytCmRNA于脑缺血再灌注 2h开始表达 ,皮质区 12h达高峰 ,纹状体区 1d达高峰 ,以后逐渐下降 ;肌苷治疗组CytCmRNA表达于再灌注 12h～ 7d在皮质区、12h～ 14d在纹状体区较对照组显著降低。　结论　脑缺血再灌注损伤可诱导CytC基因表达和神经细胞凋亡 ,肌苷可能通过对二者的抑制而发挥其神经保护作用。     

脉络宁抑制氧化应激保护缺血性脑损伤

目的 探讨脉络宁对氧化应激和缺血性脑损伤的影响.方法 健康雄性昆明小鼠126只,分为假手术组(n=18)、生理盐水对照组(n=54)和脉络宁组(n=54).建立大脑中动脉闭塞(middle cerebral artery occlusion,MCAO)模型,脉络宁组和生理盐水对照组MCAO 2 h后分别经尾静脉给予脉络宁注射液和同体积生理盐水,然后每隔24 h重复1次.在MCAO 12、24和72 h分别进行神经功能评分、脑水含量、梗死体积、膜电位以及蛋白质氧化应激代谢产物3-硝基酪氨酸(3-nitrotyrosine,3-NT)、脂质氧化应激代谢产物4-羟基壬烯醛(4-hydroxy-2-nonenal,HNE)和核酸氧化应激代谢产物8-羟基脱氧鸟苷(8-hydroxy-2'-deoxyguanosine,8-OHdG)检测.结果 在脑缺血后不同时间点,脉络宁注射液均可显著改善脑缺血小鼠的神经功能、减轻脑水肿和缩小梗死体积,其中以72 h最为显著;脉络宁注射液可逆转脑皮质和内囊区的线粒体膜电位降低,显著下调缺血后皮质、内囊和血清3-NT、HEN 和8-OHdG的升高,其中以降低HNE效果最为显著.结论 脉络宁注射液能有效保护小鼠缺血性脑损伤,其机制与抑制氧化应激,尤其是抗脂质氧化有关.     

Tamoxifen neuroprotection in cerebral ischemia involves attenuation of kinase activation and superoxide production and potentiation of mitochondrial superoxide dismutase

The purpose of this study was to enhance our understanding of the mechanisms of neuronal death after focal cerebral ischemia and the neuroprotective effects of tamoxifen (TMX). The phosphorylation state of 31 protein kinases/signaling proteins and superoxide anion (O(2)(-)) production in the contralateral and ipsilateral cortex was measured after permanent middle cerebral artery occlusion (pMCAO) in ovariectomized rats treated with placebo or TMX. The study revealed that pMCAO modulated the phosphorylation of a number of kinases/proteins in the penumbra at 2 h after pMCAO. Of significant interest, phospho-ERK1/2 (pERK1/2) was elevated significantly after pMCAO. TMX attenuated the elevation of pERK1/2, an effect correlated with reduced infarct size. In situ detection of O(2)(-) production showed a significant elevation at 1-2 h after pMCAO in the ischemic cortex with enhanced oxidative damage detected at 24 h. ERK activation may be downstream of free radicals, a suggestion supported by the findings that cells positive for O(2)(-) had high pERK activation and that a superoxide dismutase (SOD) mimetic, tempol, significantly attenuated pERK activation after MCAO. TMX treatment significantly reduced the MCAO-induced elevation of O(2)(-) production, oxidative damage, and proapoptotic caspase-3 activation. Additionally, pMCAO induced a significant reduction in the levels of manganese SOD (MnSOD), which scavenge O(2)(-), an effect largely prevented by TMX treatment, thus providing a potential mechanistic basis for the antioxidant effects of TMX. As a whole, these studies suggest that TMX neuroprotection may be achieved via an antioxidant mechanism that involves enhancement of primarily MnSOD levels, with a corresponding reduction of O(2)(-) production, and downstream kinase and caspase-3 activation.     

神经生长液对缺血性脑损伤的保护作用

目的观察神经生长液(NGD)对大鼠实验性脑缺血再灌注损伤的保护作用。方法采用大脑中动脉线栓法建立大鼠局灶性脑缺血再灌注模型,观察NGD对大鼠神经功能的恢复、血清总超氧化物歧化酶(SOD)活性、丙二醛(MDA)含量、梗死体积、病理组织损伤及细胞超微结构改变的影响。结果NGD能改善大鼠的神经功能评分,增加血清SOD活性,降低血清MDA含量,减少梗死体积(P<0.05或0.01)。NGD能改善大鼠局灶性脑缺血再灌注3d后的病理组织学损害及细胞超微结构改变。结论神经生长液对实验性脑缺血再灌注损伤具有保护作用。     

Melatonin decreases neurovascular oxidative/nitrosative damage and protects against early increases in the blood-brain barrier permeability after transient focal cerebral ischemia in mice

We have recently shown that melatonin decreases the late (24 hr) increase in blood-brain barrier (BBB) permeability and the risk of tissue plasminogen activator-induced hemorrhagic transformation following ischemic stroke in mice. In the study, we further explored whether melatonin would reduce postischemic neurovascular oxidative/nitrosative damage and, therefore, improve preservation of the early increase in the BBB permeability at 4 hr after transient focal cerebral ischemia for 60 min in mice. Melatonin (5 mg/kg) or vehicle was given intraperitoneally at the beginning of reperfusion. Hydroethidine (HEt) in situ detection and immunohistochemistry for nitrotyrosine were used to evaluate postischemic accumulation in reactive oxygen and nitrogen species, respectively, in the ischemic neurovascular unit. BBB permeability was evaluated by spectrophotometric and microscopic quantitation of Evans Blue leakage. Relative to controls, melatonin-treated animals not only had a significantly reduced superoxide accumulation in neurovascular units in boundary zones of infarction, by reducing 35% and 54% cytosolic oxidized HEt in intensity and cell-expressing percentage, respectively (P < 0.001), but also exhibited a reduction in nitrotyrosine by 52% (P < 0.01). Additionally, melatonin-treated animals had significantly reduced early postischemic disruption in the BBB permeability by 53% (P < 0.001). Thus, melatonin reduced postischemic oxidative/nitrosative damage to the ischemic neurovascular units and improved the preservation of BBB permeability at an early phase following transient focal cerebral ischemia in mice. The findings further highlight the ability of melatonin in anatomical and functional preservation for the ischemic neurovascular units and its relevant potential in the treatment of ischemic stroke.     

Melatonin decreases matrix metalloproteinase-9 activation and expression and attenuates reperfusion-induced hemorrhage following transient focal cerebral ischemia in rats

We have previously shown that melatonin reduces postischemic rises in the blood-brain barrier (BBB) permeability and improves neurovascular dysfunction and hemorrhagic transformation following ischemic stroke. It is known that activation of the matrix metalloproteinases (MMPs) plays a crucial role in the pathogenesis of brain edema and hemorrhagic transformation after ischemic stroke. We, herein, investigated whether melatonin would ameliorate MMP-2 and MMP-9 activation and expression in a rat model of transient focal cerebral ischemia. Adult male Sprague-Dawley rats were subjected to a 90-min middle cerebral artery (MCA) occlusion using an intraluminal filament. Melatonin (5 mg/kg) or vehicle was intravenously injected upon reperfusion. Brain infarction and hemorrhage within infarcts were measured, and neurological deficits were scored. The activity and expression of MMP-2 and MMP-9 were determined by zymography, in situ zymography and Western immunoblot analysis. Cerebral ischemia-reperfusion induced increased pro-MMP-9 and MMP-9 activity and expression 24 hr after reperfusion onset. Relative to controls, melatonin-treated animals, however, had significantly reduced levels in the MMP-9 activity and expression (P < 0.01), in addition to reduced brain infarct volume and hemorrhagic transformation as well as improved sensorimotor neurobehavioral outcomes. No significant change in MMP-2 activity was observed throughout the course experiments. Our results indicate that the melatonin-mediated reductions in ischemic brain damage and reperfusion-induced hemorrhage are partly attributed to its ability to reduce postischemic MMP-9 activation and increased expression, and further support the fact that melatonin is a suitable as an add-on to thrombolytic therapy for ischemic stroke patients.     

转基因小鼠bcl-xl过表达在大脑中动脉栓塞中的保护作用及机制

目的观察探讨大脑中动脉栓塞模型转基因小鼠中bcl—xl的过表达对脑缺血及缺血后再灌注是否具有保护作用及其作用机制。方法建立bcl—xl过表达转基因小鼠，将该模型小鼠与同种系野生型小鼠同时行线栓永久性阻塞大脑中动脉，在缺血24h时测其神经功能评分，观察转基因小鼠与野生型小鼠的差别。在缺血后不同时间点分别检测两种小鼠脑梗死体积及其动态变化，比较其脑组织中bcl—xl的表达量的差异、再灌注时凋亡细胞的数量和分布情况及脑中细胞色素C的表达量。结果转基因小鼠的神经功能评分低于野生型小鼠。在缺血后不同时间点转基因小鼠的梗死体积、缺血局部细胞色素C的表达、皮质缺血区内的凋亡细胞数明显少于野生型小鼠，且保护作用发生时间旱，持续时间较长。梗死前后转基因小鼠的皮质细胞bcl—xl的表达量均明显高于野生型小鼠，且梗死后两种小鼠体内的bcl—xl的表达量均有所增加，但二者之间差异无统计学意义（P〉0．05）。结论转基因小鼠中bcl—xl的过表达能降低脑梗死的体积并改善小鼠的神经功能，这种效应可能是通过抑制细胞凋亡而实现的，其机制可能是bcl—xl的过表达抑制了细胞色素C的释放。     

Interaction between inducible nitric oxide synthase and cyclooxygenase-2 after cerebral ischemia

Focal cerebral ischemia is associated with expression of both inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), enzymes whose reaction products contribute to the evolution of ischemic brain injury. We tested the hypothesis that, after cerebral ischemia, nitric oxide (NO) produced by iNOS enhances COX-2 activity, thereby increasing the toxic potential of this enzyme. Cerebral ischemia was produced by middle cerebral artery occlusion in rats or mice. Twenty-four hours after ischemia in rats, iNOS-immunoreactive neutrophils were observed in close proximity (<20 μm) to COX-2-positive cells at the periphery of the infarct. In the olfactory bulb, only COX-2 positive cells were observed. Cerebral ischemia increased the concentration of the COX-2 reaction product prostaglandin E₂ (PGE₂) in the ischemic area and in the ipsilateral olfactory bulb. The iNOS inhibitor aminoguanidine reduced PGE₂ concentration in the infarct, where both iNOS and COX-2 were expressed, but not in the olfactory bulb, where only COX-2 was expressed. Postischemic PGE₂ accumulation was reduced significantly in iNOS null mice compared with wild-type controls (C57BL/6 or SV129). The data provide evidence that NO produced by iNOS influences COX-2 activity after focal cerebral ischemia. Pro-inflammatory prostanoids and reactive oxygen species produced by COX-2 may be a previously unrecognized factor by which NO contributes to ischemic brain injury. The pathogenic effect of the interaction between NO, or a derived specie, and COX-2 is likely to play a role also in other brain diseases associated with inflammation.     

Effect of paradoxical sleep deprivation on oxidative stress parameters in brain regions of adult and old rats

The present study examined the effects of paradoxical sleep (PS) deprivation on the oxidative stress parameters: lipid peroxidation, superoxide dismutase, glutathione peroxidase, and glutathione in brain regions: cerebral cortex, striatum, hippocampus, thalamus, hypothalamus, and brain stem of adult (8 months) and old (24 months) rats. PS deprivation (96 h) was performed by the classical flower pot technique. PS deprivation did not affect oxidative stress parameters in the striatum of both age groups; and the activity of glutathione peroxidase was not affected in any of the studied brain regions in both age groups. PS deprivation decreased the levels of glutathione only in the hippocampus, thalamus and hypothalamus; the magnitude of decrease was higher in the old than in the adult age group. PS deprivation increased the superoxide dismutase activity in the cerebral cortex and brain stem but reduced it in the hippocampus, thalamus and hypothalamus in both age groups. Increases in the activity were greater in adult animals than in old ones; the decline in the activity was greater in the hippocampus of old animals than in that of the adult ones. Lipid peroxidation was reduced by PS deprivation in the cerebral cortex and brain stem but was elevated in the hypothalamus and thalamus: the magnitude of alteration in the cerebral cortex, brain stem, hippocampus and hypothalamus was higher in adult animals than in old ones. The results showed that oxidative stress was not uniformly affected in all the brain regions. The cerebral cortex and brain stem showed a fall in oxidative stress after PS deprivation; the fall was greater in the adult than in the old animals. However, the oxidative stress was elevated in the hippocampus, thalamus and hypothalamus, and old animals were more severely affected than the adult ones.