脑缺血／再灌注后大鼠海马GABA,AchE水平和迟发性神经元损害…

为探讨海马ＧＡＢＡ，ＡｃｈＥ和迟发性神经元损害的关系，观察了脑缺血／再灌注后大鼠海马亚区ＧＡＢＡ含量，ＡｃｈＥ活性和海马组组织病理改变。发现再灌注５ｍｉｎ，海马亚区ＧＡＢＡ含量显著升高，再灌注１ｈ和６－１２ｈ，ＧＡＢＡ含量明显降低，ＣＡ１区更明显。再灌注５ｍｉｎ至１ｈ，海马亚区ＡｃｈＥ活性明显长高。再注４８ｈ后，光镜下见海马ＣＡ１区神经元出现缺血性改变，提示：（１）再灌注后，ＧＡＢＡ含量减少，海马     

全脑缺血再灌注后发生迟发性神经元死亡的机制

全脑缺血再灌注后脑海马神经元（ 主要是ＣＡ１ 区） 会出现迟发性神经元死亡（Ｄｅｌａｙｅｄ ｎｅｕｒｏｎａｌ ｄｅａｔｈ ，ＤＮＤ） 的现象。该现象与兴奋性氨基酸、脂代谢、自由基、热休克蛋白、凋亡、一氧化氮及钙离子等因素有关     

脑缺血不同时间大鼠海马神经元损伤的形态学变化

目的：探讨存不同的缺血时间段大鼠海马神经元受损的形态学变化。以期为相关疾病发病机制的研究和临床治疗提供新的思路。方法：通过双侧颈总动脉水久性结扎的18月龄大鼠脑缺血模型。采用HE染色、尼氏染色、TUNEL染色和电镜观察等方法对脑缺血5、30、60、90d组海马神经元形态及细胞凋亡情况进行比较分析。结果和结论：大鼠脑缺血时间与海马神经元损伤程度密切关系。     

脑缺血／再灌注后大鼠海马GABA、AchE水平和迟发性神经元损害关系的研究

为探讨海马ＧＡＢＡ、ＡｃｈＥ和迟发性神经元损害（ｄｅｌａｙｅｄｎｅｕｒｏｎａｌｄａｍａｇｅ，ＤＮＤ）的关系，观察了脑缺血／再灌注后大鼠海马亚区ＧＡＢＡ含量、ＡｃｈＥ活性和海马组织病理改变。发现再灌注５ｍｉｎ，海马亚区ＧＡＢＡ含量显著升高，再灌注１ｈ和６～１２ｈ，ＧＡＢＡ含量明显降低，ＣＡ＿１区更明显。再灌注５ｍｉｎ至１ｈ，海马亚区ＡｃｈＥ活性明显升高。再灌注４８ｈ后，光镜下见海马ＣＡ＿１区神经元出现缺血性改变，提示：（１）再灌注后，ＧＡＢＡ含量减少、海马内源性抑制降低可能是ＣＡ＿１区ＤＮＤ的因素之一。（２）再灌注早期ＡｃｈＥ活性升高，提示Ａｃｈ代谢变化可能和ＤＮＤ有关。（３）再灌注后ＧＡＢＡ和ＡｃｈＥ在海马各亚区的明显改变，提示ＣＡ＿１区选择性易损和递质代谢变化密切相关，而ＣＡ＿１区神经元本身的生理生化特性也起着重要的作用。     

益气通络口服液对大鼠短暂性脑缺血后海马迟发性神经元死亡的保护作用

<正> 益气通络口服液具有补肾益气,活血化瘀,理气化痰的功效,临床用于缺血性心脑血管疾病的治疗收到一定效果.为进一步阐明其疗效机制,本文研究益气通络口服液对大鼠短暂性脑缺血后海马迟发性神经元死亡的保护作用.     

硫酸镁和低分子肝素联合应用对海马迟发性神经元坏死的保护作用

目的 研究硫酸镁和低分子肝素在短暂局灶性脑缺血再灌注后海马迟发性神经元坏死中的保护作用。方法 新西兰大白兔夹闭单侧颈总动脉制成模型，缺血30min再灌注72h后通过HE染色进行组织观察，同时检测血清中IL-8的含量，探讨硫酸镁和低分子肝素对保护脑的作用机制。结果 硫酸镁联合低分子肝素治疗组迟发性神经元坏死程度显著低于盐水治疗组，低分子肝素能降低缺血再灌注后血清中的IL-8含量。结论 IL-8做为一种急性炎症的趋化因子，在脑缺血时升高，可作为脑缺血炎症期或再灌注损伤重要的观察指标之一。硫酸镁没有抗炎作用，单用硫酸镁或低分子肝素的治疗效果。没有联合应用的治疗效果显著。     

L-NAME对沙土鼠脑缺血再灌流后海马区星形胶质细胞活化的作用机制研究

目的 探讨一氧化氮合酶(NOS)抑制剂左旋硝基精氨酸甲酯(L-NAME)对沙土鼠脑缺血再灌注后海马区胶质纤维酸性蛋白(GFAP)合成的影响。方法 钳夹沙土鼠的双侧颈总动脉制造脑缺血模型，应用免疫荧光法染色，观察GFAP密度的变化及分布。结果 脑缺血再灌流后海马区GFAP合成增加，GFAP阳性细胞主要分布在放射层及分子层，L-NAME能减少海马区GFAP的合成。结论 L-NAME是NOS强有力的抑制剂，L-NAME可能通过抑制NO的产生抑制了GFAP的合成。     

Long-term treadmill exercise overcomes ischemia-induced apoptotic neuronal cell death in gerbils

It has been suggested that exercise may ameliorate neurologic impairment by impeding neuronal loss following various brain insults. In the present study, the effect of long-term treadmill exercise on short-term memory and apoptotic neuronal cell death in the hippocampus following transient global ischemia in gerbils was investigated. A step-down inhibitory avoidance task, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay, and immunohistochemistry for caspase-3 were used for this study. Ischemia was induced by occlusion of both the common carotid arteries of gerbils for 5 min. Gerbils in the exercise groups were forced to run on a treadmill for 30 min once a day for 4 consecutive weeks. The present results reveal that treadmill exercise for 4 weeks improved short-term memory by suppressing the ischemia-induced apoptotic neuronal cell death in the hippocampus. Here in this study, we show that long-term treadmill exercise for 4 weeks overcomes the ischemia-induced apoptotic neuronal cell death and thus facilitates the recovery of short-term memory impairment induced by ischemic cerebral injury.     

Activation of leukocyte-endothelial interactions and reduction of selective neuronal death after global cerebral ischemia

The role of leukocyte-endothelial interactions (LEI) as part of the inflammatory response after global cerebral ischemia (GCI) is hardly understood and may be detrimental as well as beneficial. Objective of the current study was to investigate the cause-effect relationship of activated leukocytes for the development of ischemic brain damage. Mongolian gerbils were subjected to 15 min of global cerebral ischemia. A cranial window was implanted for quantitative analysis of the pial microcirculation focusing on leukocyte-endothelium interactions by intravital fluorescence microscopy up to 3 h of reperfusion. Subsequently the animals were daily screened for neurological deficits and the evolving brain damage was assessed histologically after 4 days. After global cerebral ischemia the number of rolling and adherent leukocytes increased 20- and >23-fold, respectively upon 3 h of reperfusion as compared to controls (P<0.05). Ischemic animals developed neurological deficits and showed a significant loss of neurons in selective vulnerable areas of the brain. The extent of leukocyte activation, i.e. the maximum number of rollers and stickers directly correlated to the number of viable neurons on day 4 in hippocampus, cortex, and striatum. We conclude that there is a relationship between activation of leukocyte-endothelium interactions and the reduction of ischemic brain damage after global cerebral ischemia. Activation of leukocytes may have neuroprotective potential or indicate regenerative processes.     

中风脑得平冲剂防治大鼠脑缺血再灌注损伤的实验研究

目的与方法:以雄性Wistar大鼠双侧颈总动脉缺血再灌注模型, 观察中风脑得平冲剂对脑组织含水量, 海马Ca²⁺、兴奋性氨基酸含量及形态学变化的影响, 以探讨药物的作用机制。结果与结论:大鼠脑缺血再灌注后, 有明显脑水肿及海马神经元损伤, 脑组织含水量, Ca²⁺及兴奋性氨基酸的含量明显升高, 中风脑得平冲剂表现出不同程度的抑制上述指标异常升高的作用, 从而保护神经元减轻损伤。     

Differential distribution of 68 Kd and 200 Kd neurofilament proteins in the gerbil hippocampus and their early distributional changes following transient forebrain ischemia

Summary The distribution of neurofilament (NF) proteins was studied immunohistochemically in the gerbil hippocampus with antibodies against NF68 (68 Kd molecular weight) and NF200 proteins, and changes in the distribution of NF proteins after transient ischemia were observed in order to investigate the temporal correlation between NF and delayed neuronal death. In the normal hippocampus, NF68-like immunoreactivity (NF68-LI) was densely distributed in nerve processes in CA2, CA3 and the hilus of the dentate gyrus but was less intense in CA1. In contrast, processes with NF200-LI appeared to be evenly distributed in CA1, CA2, CA3 and the dentate gyrus. Mongolian gerbils were subjected to transient ischemia for 5 min by bilateral carotid occlusion and subjected to immunohistochemistry 1, 2, 3 and 4 days after ischemia. Following transient ischemia, prior to neuronal cell death, the intensity of both NF68-LI and NF200-LI decreased in the whole hippocampal formation. This decrease was more obvious in the case of NF68-LI than NF200-LI. Four days after ischemia, when neuronal death of CA1 pyramidal cells had occurred, processes in CA1, particularly 68 Kd components, showed marked decreases in number and staining intensity, although processes in most layers of CA2, CA3 and the dentate gyrus appeared to be stained similarly to normal brain. Since NF68 protein is considered to be the major component of NF proteins and NF200 is an associated accessory protein, the current observations suggest that the poor distribution of NF68 in CA1 and the early loss of NF proteins may be closely related to selective vulnerability of CA1 pyramidal cells and delayed neuronal death.     

An ultrastructural analysis of cellular death in the CA1 field in the rat hippocampus after transient forebrain ischemia followed by 2, 4 and 10 days of reperfusion

An ultrastructural study was performed to investigate the type of cellular death that occurs in hippocampal CA1 field pyramidal neurons after 10 and 20 min of transient cerebral ischemia in the male adult Wistar rats, followed by 2, 4 and 10 days of reperfusion. The four-vessel occlusion method was used to induce ischemic insult for either 10 or 20 min, following which the animals were submitted to either 2, 4 or 10 days of reperfusion. The animals were then anaesthetised, and their brains removed, dehydrated, embedded, sectioned and examined under a transmission electron microscope. After ischemic insult, neurons from the CA1 field presented alterations, corresponding to the initial, intermediate and final stages of the degenerative process. The only difference observed between the 10 and 20 min ischemic groups was the degree of damage; the reaction was stronger in 20 min groups than in the 10 min groups. While neurons were found in the different stages of oncotic necrosis in all groups, differences were found between the groups in relation to prevalent stages. In both ischemic groups, after 2 days of reperfusion, the initial stage of oncotic necrosis was prevalent and large numbers of neurons appeared normal. In both groups, after 4 days of reperfusion, most of the neurons showed more advanced alterations, typical of an intermediate stage. In both groups, after 10 days of reperfusion, alterations corresponding to the intermediate and final stages of oncotic necrosis were also predominant. However, few intact neurons were identified and the neuropile appeared more organised, with numerous glial cells. In summary, the pyramidal neurons of the CA1 field displayed selective vulnerability and exhibited a morphological death pattern corresponding exclusively to an oncotic necrotic pathway.     

Imipramine enhances cell proliferation and decreases neurodegeneration in the hippocampus after transient global cerebral ischemia in rats

This study was aimed to determine whether imipramine chronic treatment promotes neurogenesis in the dentate gyrus (DG) and interferes with neuronal death in the CA1 subfield of the hippocampus after transient global cerebral ischemia (TGCI) in rats. After TGCI, animals were treated with imipramine (20 mg/kg, i.p.) or saline during 14 days. 5-Bromo-2′-deoxyuridine-5′-monophosphate (BrdU) was injected 24 h after the last imipramine or saline injection to label proliferating cells. In order to confirm the effect of TGCI on neuronal death and cell proliferation, a group of animals was sacrificed 7 days after TGCI. Neurogenesis and neurodegeneration were evaluated by doublecortin (DCX)-immunohistochemistry and Fluoro-Jade C (FJC)-staining, respectively. The rate of cell proliferation increases 7 days but returns to basal levels 14 days after TGCI. There was a significant increase in the number of FJC-positive neurons in the CA1 of animals 7 and 14 days after TGCI. Chronic imipramine treatment increased cell proliferation in the SGZ of DG and reduced the neurodegeneration in the CA1 of the hippocampus 14 days after TGCI. Immunohistochemistry for DCX detected an increased number of newly generated neurons in the hippocampal DG 14 days after TGCI, which was not affected by imipramine treatment. Further studies are needed to evaluate whether imipramine treatment for longer time would be able to promote survival of newly generated neurons as well as to improve functional recovery after TGCI.     

Effect of inherent epileptic seizures on brain injury after transient cerebral ischemia in Mongolian gerbils

Subthreshold excitotoxic stimuli such as brief cerebral ischemia or chemically induced seizures modulate brain injury resulting from subsequent transient ischemia. Depending on the delay between the two insults, either tolerance or cumulative damage will develop. We were interested whether non-chemically induced inherent epileptic seizures as they occur in Mongolian gerbils have an effect on the outcome of a transient global ischemia, i.e., whether they are an interfering variable in ischemia experiments. Occurrence of spontaneous seizures in adult male gerbils was registered with a video-controlled seizure monitoring system. Bilateral occlusion of common carotid arteries was carried out 2 h or 24 h after the last generalized seizure. After 4 days survival, the extent of ischemia-induced neuronal damage and glial activation were assessed in the hippocampus and striatum. No significant difference in the ischemia induced nerve cell loss was observed in cresyl violet stained sections between the 2-h or 24-h interval gerbils. Neuronal expression of endothelial nitric oxide synthase in CA1 disappeared with neuronal degeneration. Distribution and degree of upregulation of glial fibrillary acidic protein as marker for astrocytes did not differ between the two groups. We concluded that non-chemically induced inherent epileptic seizures neither protect the gerbil brain from injury nor augment the degree of damage resulting from transient forebrain ischemia. Thus, inherent epileptic seizures do not influence the outcome of the insult, making the gerbil a reliable model for studies on transient brain ischemia.     

Progressive loss of messenger RNA and delayed neuronal death following transient cerebral ischemia in gerbils

We examined mRNA, cytoplasmic RNA and structural damage in the hippocampus of the gerbil brain after transient ischemia by in situ hybridization, Acridine orange histochemistry and immunohistochemistry. Progressive decline of mRNA became visible in the CA1 region after reperfusion for 3 h and loss of cytoplasmic RNA and emergence of structural damage in 3 days. Reduction of mRNA in the CA3-CA4 region was transient. The findings suggested positive correlation between progressive loss of mRNA and delayed neuronal death.     

Neuroprotective effect of pentosan polysulphate on ischemia-related neuronal death of the hippocampus

Pentosan polysulphate (PPS) negatively charged sulphated glycosaminoglycan was studied in ischemia-related hippocampal neuronal death and compared with a low molecular weight of heparin, named dalteparin in rats. Transient global ischemia was produced by four vessel-occlusion, the occlusion of the bilateral common carotid arteries following the electrocautherization of the vertebral arteries. 3mg/kg of PPS or 300IU/kg of dalteparin was administered i.v. immediately after 7min-occlusion/reperfusion. Seven days after the operation, the animals were perfused with 4% paraformaldehyde, and paraffinized coronal brain sections measuring 6microm in thickness were stained with hematoxylin and eosin. Neuronal damage was then estimated as a ratio of the number of degenerated neurons to that of both the surviving and degenerated neurons in three distinct area of the CA1 subfield. The ratio of neuronal death increased with the length of the occlusion-time, at 5, 7 and 10min. Both PPS and dalteparin significantly inhibited the neuronal damage induced by 7min-occlusion. These results demonstrated that both PPS and dalteparin could thus protect brain neurons against ischemia/reperfusion-induced damage thus suggesting that they may be potentially useful therapeutic agents for acute ischemic stroke.