脑红蛋白高表达对创伤性脑损伤的保护作用

目的 观察脑红蛋白（Ngb）高表达对创伤性脑损伤有无保护作用.方法 将重组Ngb腺病毒载体立体定向注入大鼠脑内,使Ngb高表达,然后以Feeney＇s自由落体方法施以局灶性中度脑损伤,通过TTC染色和HE染色观察创伤性脑损伤程度是否减轻.结果 Ngb高表达组创伤性脑损伤灶体积较对照组明显减小,而且伤侧海马CA1区细胞丢失减少,凋亡细胞数明显减少.结论 脑组织内高表达Ngb可以减轻创伤性脑损伤的程度,即Ngb对创伤性脑损伤具有神经保护作用.     

Effects of nimodipine on acute focal cerebral ischemia

Nimodipine is a calcium slow channel blocker with several pharmacologic properties suggesting the potential to favorably modify outcome in focal cerebral ischemia. Thirty adult cats underwent unilateral middle cerebral artery (MCA) occlusion for 4 hours. Seventeen cats were treated with an ipsilateral intracarotid infusion of nimodipine (1 microgram kg-1 min -1) beginning 15 minutes before MCA occlusion and continuing throughout the occlusion period. Eight nimodipine treated cats maintaining MAP greater than 90 mmHg were assigned to a Higher Pressure Nimodipine (HPN) group. The remaining nine treated cats with MAP less than 90 mmHg were assigned to the Lower Pressure Nimodipine (LPN) group. Thirteen cats were untreated, receiving an isovolumetric amount of vehicle through the ipsilateral carotid artery. Local cerebral blood flow (ICBF) was continuously monitored using thermal diffusion probes. The brains, assessed for colloidal carbon perfusion, fluorescein and Evans blue staining, electroencephalographic activity (EEG), and histological changes, revealed no significant differences by any of these methods between the HPN and control animals with the exceptions of: HPN treated cats exhibited a preservation of EEG activity at 15 minutes post-occlusion compared to the untreated cats, and Post-ischemic surface colloidal carbon perfusion was better preserved in the treated cats than in the untreated cats. Mild hypotension, as demonstrated by the LPN group, negated these two positive effects. Prior to MCA occlusion, ICBF was bilaterally significantly increased after nimodipine infusion in the HPN group as compared to vehicle infusion. Intra-arterially infused nimodipine did not reduce infarct size.     

Geldanamycin protects rat brain through overexpression of HSP70 and reducing brain edema after cerebral focal ischemia

Abstract

Objective: Geldanamycin (GA), a benzoquinone ansamycin, binds HSP90, releases heat shock factor 1 and induces heat shock proteins (HSPs). HSP70, a major molecular chaperone, protects the brain against ischemic injury through inhibition of apoptotic pathways in vivo and reduced matrix metalloproteinase 9 (MMP-9) after ischemia in vitro. We hypothesized that GA would protect brain from focal ischemia via induction of HSP70 and MMP suppression in vivo.

Methods: GA or vehicle was injected into the lateral cerebral ventricles of adult male Sprague–Dawley rats using the stereotatic frame 24 hours before ischemia. Rats were subjected to 2 hour middle cerebral artery occlusions using the suture technique followed by 22 hour reperfusions. One day after ischemia, we evaluated infarction volume, brain swelling, behavioral scores and immunohistochemistry.

Results: Western blots showed that GA at 2 μg/kg induced HSP70 by 24 hours following administration. GA decreased infarct volumes and brain edema, and improved behavioral outcomes (p<0.05). Immunohistochemistry showed that GA induced HSP70 and decreased MMP-9.

Discussion: GA protects brain from focal ischemia and reduces edema. This may be due, at least in part, to GA overexpression of HSP70.     

脑红蛋白在脑梗死大鼠表达及丁苯酞干预效应

目的探讨脑红蛋白在脑梗死大鼠中的表达和丁苯酞干预在氧化应激损伤中作用。方法将90只雄性SD大鼠随机分为假手术组、模型组、治疗组。每组再分为3个亚组:1 d组、3 d组和7 d组,每亚组10只。模型组和治疗组采用线栓法制作大鼠大脑中动脉闭塞模型(MCAO),假手术组只分离不结扎。治疗组在动物苏醒后以丁苯酞植物油灌胃,假手术组和模型组同法给予等量植物油灌胃。每只大鼠在术后3h和处死前行神经功能评分,应用RT-PCR和免疫组化检测脑组织脑红蛋白(NGB)表达,化学比色法检测超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量。结果 (1)神经功能评分,模型组和治疗组术后3 h评分差异无统计学意义(P>0.05),各时间点处死前评分差异均有统计学意义(P<0.05)。(2)NGB mRNA和免疫组化表达随时间延长逐渐降低,各时间点模型组较假手术组、治疗组较模型组高,差异均有统计学意义(P<0.05)。(3)SOD活性和MDA含量随时间延长逐渐减少。SOD活性假手术组较治疗组、治疗组较模型组高,差异均有统计学意义(P<0.05);MDA含量假手术组较治疗组、治疗组较模型组低,差异均有统计学意义(P<0.05)。结论丁苯酞促进脑缺血大鼠脑红蛋白表达,减少氧化应激损伤。     

Differential effect of PARP-2 deletion on brain injury after focal and global cerebral ischemia.

Poly(ADP-ribose) polymerase-2 (PARP-2) is a member of the PARP enzyme family, and, similarly to PARP-1, catalyzes the formation of ADP-ribose polymers in response to DNA damage. While PARP-1 overactivation contributes to ischemic cell death, no information is available regarding the role of PARP-2. In this study, we evaluated the impact of PARP-2 deletion on histopathological outcome from two different experimental models of cerebral ischemia. Male PARP-2-/- mice and wild-type (WT) littermates were subjected to either 2 h of middle cerebral artery occlusion (MCAO) followed by 22 h reperfusion, or underwent 10 mins of KCl-induced cardiac arrest (CA) followed by cardiopulmonary resuscitation (CPR) and 3-day survival. After MCAO, infarct volume was reduced in PARP-2-/- mice (38%+/-12% of contralateral hemisphere) compared with WT (64%+/-16%). After CA/CPR, PARP-2 deletion significantly increased neuronal cell loss in the hippocampal CA1 field (65%+/-36% ischemic neurons) when compared with WT mice (31%+/-33%), with no effect in either striatum or cortex. We conclude that PARP-2 is a novel executioner of cell death pathways in focal cerebral ischemia, but might be a necessary survival factor after global ischemia to mitigate hippocampal delayed cell death.     

Ziprasidone attenuates brain injury after focal cerebral ischemia induced by middle cerebral artery occlusion in rats

Ziprasidone is an atypical antipsychotic drug used for the treatment of schizophrenia. Recent studies have reported that atypical antipsychotics have neuroprotective effects against brain injury. In the present study, the effect of ziprasidone on ischemic brain injury was investigated. Focal cerebral ischemia was induced by middle cerebral artery occlusion (MCAO) in rats. All the animals experienced ischemia for 1h and then underwent reperfusion. The infarct size induced by MCAO was significantly reduced in the animals that received acute treatment with 5mg/kg ziprasidone and subchronic treatment with 2.5mg/kg ziprasidone for 7 days compared with that in the vehicle-treated animals. The acute treatment with ziprasidone significantly improved neurological functions, as measured by the modified neurological severity score, in a dose-dependent manner. The subchronic treatment produced more rapid recovery from functional deficits than the vehicle treatment. The immunohistochemical investigation revealed that the subchronic treatment prevented severe loss of neuronal marker intensity and attenuated the increased in microglial marker intensity in the infarcted cortical area. These results suggest that ziprasidone has neuroprotective effects in a rat model of ischemic stroke and provide new insight for its clinical applications.     

c—fos反义寡聚核苷酸对脑缺血性损伤和电针抗损伤作用的影响

用c-fos反义寡聚核苷酸脑内微量注射、TTC染色、c-Fos免疫组织化学和电针等技术和方法,探讨即早反应基因c-fos在大鼠局灶性脑缺血（MCAO）模型的脑损伤中和电针抗局灶性脑缺血脑损伤中所起的作用。实验结果表明,局灶性脑缺血可引起c-fos在缺血侧皮质的大量表达,电针能部分抑制这种表达,使脑缺血梗死灶体积减小。在缺血中心区注射c-fos反义寡聚核苷酸后,脑内c-fos的表达基本上被完全阻断,导致脑梗死灶的体积明显增大,电针抗脑缺血脑损伤的作用也被取消,提示脑缺血后,脑内的c-fos适度表达可能对脑损伤有一定的保护作用。电针可能部分抑制了脑内c-fos表达,调整了缺血后的c-fos表达的程度,对脑缺血损伤起一定的保护作用。     

Ischemic axonal injury and its recovery after focal cerebral ischemia

After focal cerebral infarction by occluding the middle cerebral artery (MCA) of the rat, the neuronal death occurred in the ipsilateral thalamic neurons, because axons of the thalamic neurons were injured by infarction and retrograde degeneration occurred in the thalamic neurons. However, cortical neurons adjacent to the infarction survived despite their axons injured by ischemia. We employed immunohistochemical staining for 200 kilodalton (kD) neurofilament (NF), in order to study those responses of cortical and thalamic neurons against axonal injury caused by focal cerebral infarction. In the sham operated rats the immunoreactivity to the anti-200 kD NF antibody was only detected in the axon but not in the cell bodies and dendrites. At 3 days after MCA occlusion, axonal swelling proximal to the site of ischemic injury was found in the caudoputamen and internal capsule of the ipsilateral side. At 7 days after occlusion, cell bodies and dendrites of the neurons in the ipsilateral cortex and thalamus were strongly stained with anti-NF antibodies. At 2 weeks after occlusion these responses disappeared in the cortex, but lasted in the thalamus. These phenomena are caused by stasis of the slow axonal transport, because the NF is transported by slow axonal transport. In the cortical neurons impairment of slow axonal transport recovered in the early phase after injury, but in the thalamic neurons the impairment prolonged up to 3 weeks after occlusion. The early recovery of axonal transport from ischemia seemed to be essential for survival of neurons after ischemic axonal injury.     

Matrix metalloproteinase 2 gene knockout has no effect on acute brain injury after focal ischemia

Matrix metalloproteinases (MMPs) may contribute to tissue damage after cerebral ischemia. In this study, wildtype and MMP-2 knockout mice were subjected to permanent and transient (2 h) occlusions of the middle cerebral artery. Gelatin zymography showed that MMP-9 levels were increased in all brains after ischemia. MMP-2 levels did not show a significant increase in wildtype mice, and were not detectable in knockout mice. Laser doppler flowmetry demonstrated equivalent ischemic reductions in perfusion in wildtype and knockout mice. In both permanent and transient occlusion paradigms, there were no statistically significant differences between wildtype and knockout mice in terms of 24 h ischemic lesion volumes. These data suggest that MMP-2 does not contribute to acute tissue damage in this model of focal ischemia.     

舒洛地特对大鼠脑缺血再灌注损伤后脑组织的保护作用及机制

目的探讨舒洛地特对大鼠脑缺血再灌注后脑组织的保护作用及机制。方法将72只Wistar大鼠随机分为3组即假手术组、模型组、舒洛地特干预组,采用改良Zea Longa[1]线栓法制备大鼠大脑中动脉局灶性脑缺血模型,应用免疫组化法检测肿瘤坏死因子-а(TNF-а)及C-反应蛋白(CRP)的表达。结果大鼠局灶性脑缺血再灌注后缺血脑组织中TNF-a及CRP含量增加(P<0.01)。与模型组相比较,舒洛地特组TNF-a及CRP的含量减少,脑组织肿胀减轻,死亡神经元明显减少,神经功能缺损评分降低(P<0.05)。结论舒洛地特对大鼠脑缺血再灌注损伤有一定的保护作用,其机制可能是多方面的。     

Mechanisms of brain injury after global cerebral ischemia

Cerebral ischemia results in a rapid depletion of energy stores that triggers a complex cascade of cellular events such as cellular depolarization and Ca2+ influx, resulting in excitotoxic cell death. The critical determinant of severity of brain injury is the duration and severity of the ischemic insult and early restoration of CBF. Induced therapeutic hypothermia following CA is the only strategy that has demonstrated improvement in outcomes in prospective, randomized clinical trials. Although pharmacologic neuro-protection has been disappointing thus far in a variety of experimental animal models, further research efforts are directed at using some agents that demonstrate marginal or moderate efficacy in combination with hypothermia. Although the signal transduction pathways and intracellular molecular events during cerebral ischemia and reperfusion are complex, potential therapeutic neuroprotective strategies hold promise for the future.     

Olanzapine attenuates brain damage after focal cerebral ischemia in vivo

Atypical antipsychotic drugs are widely used in the treatment of schizophrenia. These agents are discovered to have some additional beneficial effects beyond their effectiveness as antipsychotic drugs. Among these initially unexpected effects are their potential effects as mood stabilizers in bipolar disorder and their efficacy in improving long-term outcome in schizophrenia. These effects recently raised the question whether these drugs may also have some neuroprotective effect in the brain. To examine this matter, in this study we evaluated the neuroprotective effect of olanzapine after permanent focal cerebral ischemia. Anaesthetized male C57BL/6j mice were submitted to permanent thread occlusion of the middle cerebral artery (MCA). Olanzapine (0.1 and 1 mg/kg) or vehicle was applied intraperitoneally just after permanent ischemia. Twenty-four hours after permanent ischemia, brain injury was evaluated by triphenyltetrazolium chloride staining (TTC). Olanzapine (0.1 and 1 mg/kg) showed significant neuroprotection after permanent focal cerebral ischemia.     

Risperidone attenuates brain damage after focal cerebral ischemia in vivo

Since their introduction, atypical neuroleptic agents have been discovered to have some beneficial effects beyond their effectiveness as neuroleptic drugs. Among these initially unexpected effects are their potential effects as mood stabilizers in bipolar disorder and their efficacy in improving long-term outcome in schizophrenia. These effects recently raised the question whether these drugs may also have some neuroprotective effect in the brain. To examine this matter, in this study we evaluated the neuroprotective effect of risperidone after permanent focal cerebral ischemia. Anaesthetized male C57BL/6j mice were submitted to permanent thread occlusion of the middle cerebral artery (MCA). Risperidone (0.1, 1 or 10 mg/kg) or vehicle was applied intraperitoneally just after permanent ischemia. Twenty-four hours after permanent ischemia, brain injury was evaluated by triphenyltetrazolium chloride staining (TTC). Risperidone (0.1, 1 and 10 mg/kg) showed significant neuroprotection after permanent focal cerebral ischemia.     

丹参乙酸镁对大鼠局灶性脑缺血损伤后神经营养因子表达的影响

目的观察丹参乙酸镁对局灶性脑缺血后大鼠神经行为、梗死体积、组织形态及缺血半暗带神经生长因子(NGF)、脑源性神经营养因子(BDNF)表达的影响,探讨丹参乙酸镁的神经保护作用及其机制。方法健康雄性SD大鼠36只随机分为3组,Ⅰ组(假手术+安慰剂组);Ⅱ组(脑缺血+安慰剂组);Ⅲ组(脑缺血+药物组)。用线栓法建立动物模型,不给予再灌注,各组在术后48h断头取脑,处死前行神经功能评分,用氯化三苯基四氮唑(TTC)染色计算脑梗死体积,用苏木精-伊红(HE)染色观察组织学形态,用免疫组织化学染色观察NGF、BDNF的表达。结果Ⅰ组在神经功能评分、梗死体积、组织形态及大脑皮质相应部位NGF、BDNF阳性细胞数均正常。与Ⅱ组相比,Ⅲ组的神经功能评分和梗死体积比较差异无统计学意义(P>0.05);光镜下,Ⅱ组、Ⅲ组缺血性病理改变均较重,两组之间无明显差别;Ⅲ组缺血半暗带NGF、BDNF阳性神经元数较Ⅱ组增加(P<0.05)。与Ⅰ组相比,Ⅱ组缺血半暗带NGF、BDNF阳性神经元数增加(P<0.05)。结论丹参乙酸镁可增加脑缺血损伤后缺血半暗带NGF、BDNF的表达,但其发挥的神经保护作用并不明显。     

Delayed inhibition of c-Jun N-terminal kinase worsens outcomes after focal cerebral ischemia

The stress-activated protein kinase c-Jun N-terminal kinase (JNK) is a central regulator in neuronal death cascades. In animal models of cerebral ischemia, acute inhibition of JNK reduces infarction and improves outcomes. Recently however, emerging data suggest that many neuronal death mediators may have biphasic properties-deleterious in the acute stage but potentially beneficial in the delayed stage. Here, we hypothesized that JNK may also have biphasic actions, so some caution may be required in the development of JNK inhibitors for stroke. Sprague Dawley rats underwent 90 min transient occlusions of the middle cerebral artery. Acute treatment (10 min poststroke) with the JNK inhibitor SP600125 reduced infarction volumes. In contrast, delayed treatment (7 d poststroke) worsened infarction volumes and neurological outcomes. Immunostaining of peri-infarct cortex showed that JNK inhibition suppressed surrogate markers of neurovascular remodeling, including matrix metalloproteinase-9 in GFAP-positive astrocytes and microvascular density. Consistent with these in vivo data, SP600125 significantly suppressed in vitro angiogenesis in rat brain endothelial cultures. Our data provide initial proof-of-concept that the neuronal death target JNK may also participate in endogenous processes of neurovascular remodeling and recovery after cerebral ischemia.     

细胞周期调控对局灶性缺血性脑损伤后的保护作用

目的通过抑制细胞周期素依赖激酶(Cyclindependentkinases,CDKS)来对神经元凋亡进行干预,以探讨细胞周期调控与细胞凋亡的关系。方法建立光化学法诱导大鼠局灶性脑缺血模型,并随机分为脑缺血组(对照组和干预组)和假手术组,采用HE染色显示梗死灶,并测定其面积占脑片面积百分率的平均值;通过TUNEL方法检测神经元凋亡;免疫印迹(Westernblot)观察损伤侧皮层周期素蛋白A(CyclinA)和周期素蛋白B1(CyclinB1)的表达。结果缺血后24h对照组梗死灶面积占脑片面积百分率的平均值明显大于干预组(P<0.05),缺血后梗死灶周围可见大量TUNEL阳性染色细胞,且对照组数量明显多于干预组(P<0.05),二者均多于假手术组(P<0.05);缺血后24h干预组大鼠NeuN TUNAL双标阳性表达率明显弱于对照组大鼠(P<0.05);Westernblot显示对照组CyclinA和CyclinB1的表达明显高于干预组(P<0.05)。结论细胞周期抑制剂可部分抑制缺血边缘区神经元的凋亡及减小脑梗死面积,这提示细胞周期调控可能参与了神经细胞的凋亡过程。