Ultrastructural investigation of the CA1 region of the hippocampus after transient cerebral ischemia in gerbils

Summary Ultrastructural damage leading to delayed neuronal death was investigated in the mid-CA1 region of the hippocampus from the stratum (str.) moleculare to oriens after transient bilateral forebrain ischemia in Mongolian gerbils. After ischemia for 5 min without recirculation, mild swelling of the peripheral part of the apical and basal dendrites was already apparent in the str. moleculare and str. oriens. Mitochondria in the dendrites were also swollen in the same area. During recirculation for 12 h to 3 days, swelling of the dendritic cytoplasm persisted with formation of microvacuoles, but swelling of mitochondria receded. Microvacuolation and loss of microtubules were also observed in the proximal part of the dendrites during this period, and swelling and disruption of internal cristae were observed in mitochondria after recirculation for 3 days. The dendrites became severely degenerated after recirculation for 4 days. In the pyramidal cell bodies, no abnormality was observed at the end of ischemia for 5 min, but disaggregation of polyribosomes and swelling of the endoplasmic reticulum were observed 12 h after recirculation. Proliferation of the endoplasmic reticulum in parallel arrays occurred after recirculation for 1 day and persisted. Severe degeneration of the pyramidal cell bodies was obvious after recirculation for 4 days. The findings observed in the present investigation suggested that the neuronal structure most vulnerable to ischemia was the peripheral part of the dendrites and postischemic neuronal damage occurred early in this part of the dendrites.Supported by the grant NS-06663 from the National Institutes of Health, U.S. Public Health Service     

Immunoelectron microscopic investigation of creatine kinase BB-isoenzyme after cerebral ischemia in gerbils

Alteration of creatine kinase BB-isoenzyme (CK-BB) was investigated in the vulnerable CA1 region of the hippocampus of ischemic and postischemic gerbil brains using immunoelectron microscopy. CK-BB existed in the neuronal perikarya, dendrites and axons as well as in astroglias in the normal gerbil brain. Immunocytochemical reaction products were associated with microtubules and polyribosomes. Propagation of ischemic and postischemic damage with disintegration of microtubules was observed in the dendro-somatic direction in neurons, which progressed in parallel with dispersion and loss of the immunocytochemical reaction for CK-BB in the dendroplasm. After reperfuson for longer than 24 h, CK-BB was also observed in the extracellular space. The present result supported the notion that loss of the immunohistochemical reaction for CK-BB which has been observed by light microscopy after cerebral ischemia, was at least partly due to dispersion of this enzyme caused by disintegration the mirotubules and extracellular leakage of this enzyme, although other processes, including degradation of CK-BB per se, were also possible. The loss of CK-BB from the neuronal structure may delay the recovery from ischemic damage and may eventually lead to neuronal death.The present investigation was supported by the grant NS-06663 from the National Institute of Health, U.S. Public Health Services     

Intracerebral distribution of albumin after transient cerebral ischemia: light and electron microscopic immunocytochemical investigation

Summary The blood-brain barrier breaks down following cerebral ischemia, but the exact sequence of events for extravasation of serum proteins and their parenchymal distribution remain uncertain. We studied the distribution of serum albumin in the hippocampus of the gerbil brain using light and electron microscopic immunocytochemical techniques. With light microscopy, there was no reaction for albumin for the first 12 h after unilateral common carotid artery occlusion for 10 min and reperfusion. At 12 h, the reaction was weak and limited to the neuropil in the subiculum-CA1 region (between the subiculum and the medial CA1 region). After 24 h, the reaction became intense in the neuropil and neuronal perikarya in the subiculum-CA1 and medial CA1 regions. The electron microscopic immunocytochemical study of the subiculum-CA1 and medial CA1 regions revealed electron-dense immunoprecipitates in the extracellular space and the peripheral part of the apical dendrites as early as 30 min after reperfusion and in the astrocytic cytoplasm after reperfusion for 1 h. However, immunoprecipitates were not found in the neuronal perikarya until after reperfusion for 24 h. The present study demonstrated prompt appearance of albumin in the extracellular space of the brain parenchyma after re-establishment of cerebral circulation and prompt accumulation in the peripheral part of the dendrites with spreading to neuronal perikarya, likely in the process of degeneration and death.Supported by the grant NS-06663 from the National Institutes of Health, U. S. Public Health Service     

Immunoelectron microscopic study of tubulin and microtubule-associated proteins after transient cerebral ischemia in gerbils

Summary Differential vulnerability of microtubule components to cerebral ischemia has been reported previously. We investigated the disintegration of microtubules using immunoelectron microscopy for -tubulin and microtubule-associated protein 1A and 2 (MAP1A and 2). Mongolian gerbils were subjected to bilateral carotid occlusion for 10 to 30 min and reperfusion for up to 72h following ischemia for 10 min. After ischemia for 10 min, some dendrites in the stratum moleculare of the subiculum-CA1 region lost immunoreaction products for -tubulin and MAPs. Loss of the reaction products spread to the medial CA1 region during progressive ischemia for 30 min. In some dendrites, electron-dense precipitates for MAPs were dispersed in the dendritic cytoplasm with little reaction product on microtubules and without alteration of the reaction for -tubulin. After recirculation, loss of electron-dense precipitates for -tubulin and MAPs, as well as disintegration of microtubules, propagated further to the medial CA1 region and to the proximal dendrites. The present study demonstrated prompt disintegration of microtubules with rapid disappearance of the reaction for MAPs which seemed to be caused by detachment of MAPs from the microtubule cores.     

Morphological studies on cerebral cortical lesions induced by transient ischemia in Mongolian gerbil —Diffuse and peripheral pallor of the neuronal perikarya

Summary Unilateral transient cerebral ischemia was produced in Mongolian gerbils by clipping the left common carotid artery for 1h. About 60% of the gerbils with neurological symptoms had post-ischemic seizures. The majority of those that had seizures died within a few days, and sections of their cerebral cortices contained many dark and shrunken neurons. However, the gerbils that did not have seizures survived without any severe complications. In the cerebral cortex of the latter, the neurons with diffuse or peripheral pallor of the perikarya were seen along with a small number of dark and shrunken neurons. Diffuse pallor occurred within a few hours following ischemia in layers III, V and VI, and disappeared 1 or 2 days after recirculation. Electron microscopically, these neurons showed dispersion of ribosomes, simple and elongated profiles of rough endoplasmic reticulum (r-ER), clustered vacuoles, and mild to moderate mitochondrial swelling. Occasional net-like tubulomembranous structures, probably derived from r-ER, were observed. On the other hand, peripheral pallor became apparent after 5 days following ischemia, usually involving layer II first and gradually extending to the deeper layers. Concomitantly, the amount of neuropil decreased and the dendrites exhibited tortuosity and irregularity in layer II. Electron microscopically, these neurons showed marked swelling of peripheral perikarya and polyribosomes and organelles were located peripherally to the nuclei. In addition, numerous degenerated axon terminals and distended dendrites were observed around the neurons. These observations indicate that diffuse pallor represents damage directly induced by ischemia and subsequent recirculation, while peripheral pallor is the delayed and remote effect of ischemia, probably due to degeneration of neuronal processes.     

Ultrastructural pathology of dendritic spines in epitumorous human cerebral cortex

Summary Ultrastructural changes in the human epitumorous cerebral cortex were examined. A swelling of nerve cell perikarya, dendrites and axon terminals, and an occasional hyperplasia and disarray of microtubules and neurofilaments were observed. Accumulations of lysosomes, tubuloreticular structures and intracytoplasmic or intramitochondrial crystalloid inclusions were also found. Some myelinated axons were degenerated. Astrocytes and their processes were focally swollen. A mild swelling was found also in microgliocytes. Oligodendrocytes occasionally contained accumulations of dense bodies. Special attention was paid to dendritic spines. The spine surface morphology changed distinctly on swollen dendritic segments. The necks of most spines were short and wide, and numerous sessile forms were present in this location. The spine apparatus was often hypertrophied and disorganized. Smoothing out of spines on swollen dendrites is described and a possible functional significance of the observed changes in the symptomatology of brain tumors is hypothesized.     

大鼠急性局灶性脑缺血再灌注脑组织NO含量和NOS活性的变化

目的探讨一氧化氮（ＮＯ）和神经元型ＮＯ合酶（ｎＮＯＳ）是否参与急性局灶性脑缺血再灌注的发病机理。方法采用栓红法建立大鼠大脑中动脉阻塞（ＭＣＡＯ）模型,观察脑组织ＮＯ含量和一氧化氮合酶（ＮＯＳ）活性的变化及ｎＮＯＳ抑制剂７－硝基吲唑（７－ＮＩ）对再灌注期两者的影响。结果缺血３０分种ＮＯ含量和ＮＯＳ活性显著升高,缺血３小进两者下降;再灌注３０分种ＮＯＴ和ＮＯＳ再次升高,而再灌注３小时两者又下降。７－Ｎ     

Pathogenesis of substantia nigra lesions following hyperglycemic ischemia: changes in energy metabolites, cerebral blood flow, and morphology of pars reticulata in a rat model of ischemia

A spectacular spongiotic lesion, symmetrical in distribution and restricted to the pars reticulata of the substantia nigra (SNPR) has recently been described in hyperglycemic rats surviving 1-18 h after a brief period of transient ischemia. The purpose of this study was to clarify the pathogenesis of the lesion. In order to study whether the lesion was due to changes occurring during ischemia, local cerebral blood flow (l-CBF) and energy metabolites were measured in the substantia nigra (SN) and in other brain areas. Furthermore, brains were examined by light and electron microscopy immediately after ischemia and in the early recirculation period. Autoradiographic CBF measurements showed ischemia flow levels in the SN of 30-40% of control, similar in normo- and hyperglycemic rats. Thus, although ischemic, this structure had a considerable amount of residual flow. There was also a corresponding partial preservation of the adenylate energy charge. However, lactate levels were high, and in hyperglycemic subjects they rose to values previously described during status epilepticus (about 25 mumol/g). In hyperglycemic animals, neuronal alterations were consistently present in SNPR by the end of the 10-min period of ischemia. They included clumping of nuclear chromatin and subplasmalemmal clearing of the perikaryon. Some mitochondrial swelling was present in neuronal perikarya and in dendrites. The normal alignment of microtubules in the dendrites was disturbed, but there was no or only slight swelling of the dendrites. Aggregation of synaptic vesicles was a conspicuous finding in axonal terminals, which were also slightly swollen. Otherwise, the axons appeared largely spared. Microvessels looked quite intact. Similar cellular changes were observed in the early recovery period. Dendrites, however, started to swell, and their expansion finally caused the spongiotic appearance of the pars reticulata. The appearance of the dendritic lesions is strongly suggestive of transmitter-mediated ("excitotoxic") damage. However, it seems likely that the marked acidosis is injurious as well. We tentatively conclude that both mechanisms interact to give the final lesion. The results, and those previously obtained in epileptic seizures, suggest that mitochondria of SN neurons and neuronal processes are particularly prone to damage.     

Differential vulnerability of microtubule components in cerebral ischemia

Summary Differential vulnerability of the major components of microtubules was examined in ischemic gerbil brains by a light microscopic, immunohisto-chemical method using monoclonal antibodies for microtubule-associated protein (MAP) 1A and MAP2, polyclonal antibody for MAP1 and 2 as well as monoclonal antibody for -tubulin. Progressive cerebral ischemia during unilateral carotid occlusion for 5, 15 and 120 min and reperfusion for 3, 12 and 48 h following bilateral carotid occlusion for 10 min were studied. Ischemic lesions in the subiculum-CA1 region were visualized by all antibodies after ischemia for 5 min but the antibody for -tubulin was less sensitive. The antibody for -tubulin was also less sensitive than antibodies for MAPs for detection of early postischemic lesions. Differential sensitivity was also observed in the cerebral cortex and other brain regions. Microtubules in myelinated axons were more stable than those in dendrites. The observed loss of immunohistochemical reactivities for MAPs and -tubulin may have been caused by activation of calcium-dependent proteolytic enzymes such as calpains. The discrepancy between MAPs and -tubulin could be due to differences in affinities or topographic distributions of these proteins within microtubules.Supported by the grant NS-06663 from the National Institutes of Health, U.S. Public Health Service     

缺血预处理对沙土鼠脑缺血再灌注后线粒体功能的影响

目的 观察缺血预处理对沙土鼠脑缺血及再灌注后脑组织线粒体功能的影响。方法 用沙土鼠双侧颈总动脉结扎制成全脑缺血模型（缺血２０分钟,再灌注３０分钟）。动物随机分为预缺血组、模型组和假手术组。预缺血组给予两次（各２分钟）缺血预处理（间隔４８小时）。用氧电极法测定呼吸功能和呼吸链的氧化酶（ＮＡＤＨ氧化酶、琥珀酸氧化酶、细胞色素Ｃ氧化酶）活性。结果 缺血模型组动物的呼吸控制率、磷氧比及氧化磷酸化效率均较假     

Citicoline decreases phospholipase A2 stimulation and hydroxyl radical generation in transient cerebral ischemia

Neuroprotection by citicoline (CDP-choline) in transient cerebral ischemia has been demonstrated previously. Citicoline has undergone several Phase III clinical trials for stroke, and is being evaluated for treatment of Alzheimer's and Parkinson's diseases. Phospholipid degradation and generation of reactive oxygen species (ROS) are major factors causing neuronal injury in CNS trauma and neurodegenerative diseases. Oxidative metabolism of arachidonic acid (released by the action of phospholipases) contributes to ROS generation. We examined the effect of citicoline on phospholipase A(2) (PLA(2)) activity in relation to the attenuation of hydroxyl radical (OH.) generation after transient forebrain ischemia of gerbil. PLA(2) activity (requires mM Ca(2+)) increased significantly (P < 0.05) in both membrane (50.2 +/- 2.2 pmol/min/mg protein compared to sham 35.9 +/- 3.2) and mitochondrial fractions (77.0 +/- 1.2 pmol/min/mg protein compared to sham 33.9 +/- 1.2) after cerebral ischemia and 2 hr reperfusion in gerbil, which was significantly attenuated (P < 0.01) by citicoline (membrane, 39.9. +/- 2.2 and mitochondria, 41.9 +/- 3.2 pmol/min/mg protein). In vitro, citicoline and its components cytidine and choline had no effect on PLA(2) activity, and thus citicoline as such is not a PLA(2) inhibitor. Ischemia/reperfusion resulted in significant OH. generation (P < 0.01) and citicoline significantly (P < 0.01) attenuated their formation (expressed as 2,3-dihydroxybenzoic acid/salicylate ratio; ischemia/24 hr reperfusion, 6.30 +/- 0.23; sham, 2.56 +/- 0.27; ischemia/24 hr reperfusion + citicoline, 4.85 +/- 0.35). These results suggest that citicoline affects PLA(2) stimulation and decreases OH. generation after transient cerebral ischemia.     

The time course of glucose metabolism in rat cerebral ischemia with middle cerebral artery occlusion-reperfusion model and the effect of MK-801

Abstract

Following cerebral ischemiai, the extracellular concentration of excitatory amino acids increases, and the excitatory cell death may play an important role contributing to ischemic neuronal damage. Although sequential metabolic changes in permanent local cerebral ischemia have been reported\ the effect of reperfusion in local cerebral ischemia on glucose metabolism is less clear. In order to investigate the time course change of glucose metabolism in a middle cerebral artery occlusion-reperfusion model and the effect of dizocilpin (MK-801) on glucose metabolism, the 4C-Deoxyglucose method was used. Hypermetabolism occurred at 30 min after the middle cerebral artery (MCA) occlusioni, and reached a peak at 60 min after ischemia in both ischemic core and penumbra. The shift from hyper- to hypometabolism was observed after the ischemia. The reperfusion facilitated the decrease of cerebral glucose metabolism in the ischemic region following 2 h of MCA occlusion. The pretreatment of MK-801 (0.4 mg kg~ 7J inhibited both increased glucose metabolism during ischemia and decreased glucose metabolism during reperfusion. These findings support the hypothesis that excitation-induced hypermetabolism plays a major role in the ischemic insult following focal cerebral vascular occlusion. [Neurol Res 1996; 18: 505-508]     

局灶性脑缺血再灌注内皮细胞缺血耐受性观察

目的 观察脑缺血再灌注内皮细胞的形态学和超微结构变化，了解内皮细胞对不同缺血时间的耐受性。方法 SD大鼠53只，随机分为假手术组、单纯缺血组、缺血再灌注组。采用线栓并环扎的方法建立大鼠局灶脑缺血模型。冠状面按A、B、C、D、E5等分切脑，取C片脑组织TTC染色定位边缘区。取D片常规脱水、透明、包埋、切片，HE染色，光镜观察。B片取缺血周围区和中心区脑组织，经固定包埋，半簿切片1μm，超溥切片JEOL100透射电镜下观察。结果 光镜下：缺血3h可见神经毡疏松，小血管周嗣水肿，缺血12h再灌注3h可见缺血中心区小动脉破裂出血。电镜下：缺血3h可见毛细血管内皮细胞核肿胀，胞浆内胞饮增加，星形胶质足突层空泡化呈＋：缺血3h再灌注3h中心区足突层空泡化呈（＋＋），边缘区呈（＋＋＋）；缺血6h再灌注3h可见内皮紧密连接开放，足突层空泡化呈（＋＋＋）；缺血12h再灌注3h后胞饮明显减少，线粒体肿胀也少见，但紧密连接开放增加，足突层空泡化呈（＋＋＋～＋＋＋＋）。结论 内皮细胞存缺血3h即可发生明显的结构变化，缺血6h可见内皮细胞紧密连接开放，缺血12h后可发生出血性转化，出血转化多发生于再灌注后的缺血中心区。     

Effect of transient cerebral ischemia on γ-aminobutyric acidA receptor α1-subunit–immunoreactive interneurons in the gerbil CA1 hippocampus

Following transient cerebral ischemia, pyramidal cells within area CA1 of the hippocampus exhibit delayed neuronal death. While interneurons within this sector continue to survive long-term, there is evidence that some interneurons in area CA1 are vulnerable to damage. To determine the nature of vulnerability in a neurochemically heterogeneous population of interneurons throughout area CA1, we examined the labeling of γ-aminobutyric acid (GABA)ergic interneurons with an antibody to the GABA_A receptor α₁-subunit 1–35 days following cerebral ischemia in the Mongolian gerbil. Unlike some other GABA interneuron markers, this antibody labels both the dendrites and soma of interneurons, allowing dendritic structure to be examined. Three to four days following ischemia, the pyramidal cells in area CA1 had degenerated, and the α₁-subunit–positive interneurons in all layers of area CA1 had developed severely beaded dendrites. At longer survival times (21–35 days), the α₁-subunit–immunolabeled dendrites of these interneurons had a fragmented appearance. In contrast, interneurons bordering str. oriens and alveus typically exhibited normal dendritic morphology. Despite the pathologic changes, there was no evidence of interneuron loss in area CA1 up to 35 days post-ischemia. Normal interneuron morphology was also observed in area CA3 and dentate gyrus, regions where neither pyramidal neurons nor granule cells, respectively, die following 5 min of cerebral ischemia. To determine if the ischemia-induced changes in interneuron morphology could be prevented, diazepam was administered 30 and 90 min following ischemia. Diazepam produces long-term neuroprotection of area CA1 pyramidal neurons. In gerbils sacrificed 35 days after ischemia, diazepam markedly attenuated the dendritic beading of the area CA1 interneurons. In addition, the dendrites did not display the fragmented labeling by the α₁-subunit antibody. Thus, despite their long-term survival, CA1 hippocampal interneurons in the gerbil can express severe structural abnormalities after transient cerebral ischemia coincident with pyramidal cell degeneration, and the injury to the dendrites can be prevented by the neuroprotectant diazepam. Hippocampus 1997; 7:511–523. © 1997 Wiley-Liss, Inc.     

全脑缺血再灌注兴奋性氨基酸、线粒体钙、钙调素含量的变化

目的：采用大鼠全脑缺血再灌注模型,观察海马组织兴奋性氨基酸、线粒体钙、钙调素含量的变化,研究分析脑缺血再灌注损伤中兴奋性氨基酸与钙平衡紊乱的变化和作用。方法：测定假手术组,缺血３０ｍｉｎ再灌注６０ｍｉｎ和缺血３０ｍｉｎ再灌注１２ｈ组,脑海马组织兴奋性氨基酸、线粒体钙、钙调素的含量。结果：缺血３０ｍｉｎ再灌注６０ｍｉｎ海马组织兴奋性氨基酸明显低于假手术组（Ｐ＜０．０１）,线粒体钙、钙调素含量显著性高于假手术组（Ｐ＜０．０１）,缺血３０ｍｉｎ再灌注１２ｈ组同假手术组比较没有显著性差异（Ｐ＞０．０５）。结论：我们从鼠脑缺血再灌注时线粒体钙、钙调素含量升高证实钙平衡紊乱参于兴奋性氨基酸的缺血再灌注脑损伤过程     

大鼠局灶性脑缺血再灌注后bcl-2蛋白在大脑皮质的表达

目的观察bcl-2蛋白在大鼠局灶性脑缺血再灌注(FCIR)后表达的变化。方法大脑中动脉内线栓法(MCAO)建立缺血再灌注(IR)模型,用免疫组化(SP)法观察bcl-2蛋白不同时间的表达。HE染色观察各个时间点细胞形态学变化。结果脑缺血2h再灌注2hbcl-2表达升高(P<0.01),IR6h达到高峰,IR12h开始下降。结论随着脑缺血再灌注时间延长脑损伤加重,bcl-2蛋白表达减少,bcl-2蛋白表达增加对细胞存亡有重要意义。     

短暂脑缺血再灌注后大鼠大脑皮质ATP含量的动态变化

目的　探讨短暂脑缺血再灌注后大鼠大脑皮质ATP含量的动态变化及其与神经功能恢复之间的关系。方法　采用线栓法建立大鼠大脑中动脉闭塞 (MCAO)模型 ,缺血 10min后于再灌注后 0h、1h、3h、6h、12h、2 4h和 72h应用毛细血管电泳法分别测定额顶叶皮质的ATP含量 ,观察其变化规律。结果　缺血 10min后额顶叶皮质ATP的含量急剧下降至对照组的 2 0 %。再灌注后ATP的含量逐渐恢复 ,于再灌注后 1h、3h、6h和 12h恢复至对照组的 70 .5 %、6 5 .7%、84 .8%和 86 .9%。再灌注后 2 4hATP含量再次下降 ,再灌注后2 4h和 72hATP含量仅为对照组的 5 0 % ,与对照组相比差异均有显著性 (P <0 0 1,P <0 0 5 )。缺血 10min再灌注后大鼠肢体功能可逐渐恢复 ,但再灌注后 2 4h起出现不愿活动和进食等表现。结论　短暂脑缺血再灌注后大鼠额顶叶皮质存在细胞能量系统功能恢复滞后的现象。同时 ,随着再灌注的进行还出现了继发性细胞能量系统功能衰竭的现象 ,这可能与脑缺血再灌注后的神经功能延迟恢复有关     

Acute ultrastructural response of hypoxic hypoxia with relative ischemia in the isolated brain

Summary The acute cortical response to surgical brain isolation and subsequent extracorporal normoxic or 30 min hypoxic (PaO₂=20 mm Hg) perfusions (hypoxic hypoxia with relative ischemia) was evaluated. Cerebral blood flow, arterial pH and CO₂ were maintained constant during both perfusions; only the arterial oxygen content was changed. The isolated brain model used in this and previous investigations produces no qualitative ultrastructural changes in the neocortex following brain isolation and normoxic perfusion. However, the acute cortical structural response to 30 min of hypoxic hypoxia with relative ischemia demonstrated a number of important observations. Hypoxic hypoxia produced ultrastructural responses common to cerebral ischemia such as nuclear chromatin clumping, nucleolar condensation and cytoskeletal breakdown. Although neuronal abnormalities seen after 30 min of hypoxic hypoxia were similar to those acute neuronal changes observed following complete cerebral ischemia without recirculation, they differed three ways: (a) mitochondrial swelling and microvacuolation were observed in many cortical pyramidal neurons. (b) Glycogen particles within astroglial processes were observed even after a 30-min period of hypoxic hypoxia. (c) Perivascular astroglial swelling was minimal despite considerable perineuronal swelling. In contrast, incomplete cerebral ischemia produces mitochondrial changes similar to those in hypoxic hypoxia but also causes the depletion of tissue glycogen and perivascular glial swelling. Thus, hypoxic hypoxia with relative ischemia produces a unique acute ultrastructural response compared to either complete or incomplete cerebral ischemia.Supported by an NIH grant NS05961     

Effects of melatonin on mitochondria after cerebral isehemic reperfusion

Melatonin has been regarded as a free radical scavenger and antioxidant. In both in vitro and in vivo experiments. Melatonin was found to protect cells, tissues and organs against oxidative damage induced by a variety of free radical generating agents and processes, e.g., ischemic reperfusion. The mechanisms underlying these interactions have not been defined. The goal of the present study was to observe the effects of melatonin on rnitochondria after cerebral ischemic reperfusion and the mechanisms of neuroprotection of melatonin by gerbil ischemic model. Male Mongolian gerbils were subjected to 10 min of forebrain ischemia by occlusion of both common carotid arteries under anesthesia. Melatonin(0.8 mg/kg) was administrated intraperitoneum 30 min befbre arteries occlusion. We measured the respiratory function of mitochondria, the activities of ATPase, the free mitochondrial calcium contents and the GSH level of mitochondria. The results show that oxidative phosphorylation function of mitochondria was damaged after cerebral ischemic reperfusion. And mitochondrial calcium was overloaded after cerebral ischemic reperfusion. And the level of GSH in mitochondria decreased after cerebral ischemic reperfision. It is concluded that melatonin have neuroprotection effects after cerebral ischemic repertusion and this effects probably related to the protection mitochondria.     

脑缺血选择性海马CA1区神经元损害的实验研究

采用Ｐｕｌｓｉｎｅｌｉ－Ｂｒｉｅｒｌｅｙ４血管阻塞脑缺血模型观察了大鼠全脑缺血２０ｍｉｎ再灌流８ｈ，ｃ－ｆｏｓ基因表达及再灌流７ｄ海马ＣＡ１区迟发性神经元损害。在缺血再灌流早期（８ｈ）海马ＣＡ１区极少ｃ－ｆｏｓ表达，而齿状回、海马ＣＡ３区、杏仁核大量ｃ－ｆｏｓ表达。缺血再灌流晚期（７ｄ）镀银染色显示海马ＣＡ１区神经元及其突触终末带呈黑色溃变相，而齿状回、海马ＣＡ３区、杏仁核呈金黄色正常相。相邻切片ＨＥ染色示缺血组海马ＣＡ１区核完整的锥体细胞数（５±２．６个／２００μｍ）与对照组（４０±２．９个／μｍ）比较差异有显著意义（Ｐ＜０．０１）。脑缺血诱导的ｃ－ｆｏｓ基因表达对于缺血易损海马ＣＡ１区迟发性神经元坏死可能起直接的调控作用。