Immunohistochemical changes of the blood-brain barrier in rat spinal cord after heavy-ion irradiation

Changes in the blood-brain barrier (BBB) of the rat spinal cord after irradiation with heavy ion were investigated ultrastructurally and immunohistochemically by using SMI 71, a monoclonal antibody against rat endothelial barrier antigen (EBA); anti-ZO-1, a polyclonal antibody against endothelial tight junctions, anti-rat serum to extravasated serum, and anti-vascular endothelial growth factor (VEGF). The lower thoracic and lumbar cord of male Wistar rats was singly irradiated with a carbon beam at a dose of 30 Gy. Rats were sacrificed before or after the onset of hind limb paralysis. Histologically, white-matter vacuolization was observed from 13 weeks after irradiation, and white-matter necrosis was first noted at 17 weeks. SMI 71 staining was decreased or lost 13 weeks after irradiation, just prior to the formation of white-matter necrosis, and was almost completely lost in the center and periphery of the white-matter necrosis. Although ZO-1 expression and tight junctions in the ultrastructure were preserved at that time, serum leakage occurred almostly completely in parallel with the changes in EBA. Therefore, carbon-ion irradiation at a dose of 30 Gy induces BBB breakdown 13 weeks after irradiation. The SMI 71-negative blood vessels were sparsely distributed throughout the entire white and gray matter, and there was no evidence of preferential localization. Immunostaining of smooth muscle actin showed that most of the SMI 71-negative blood vessels were veins or capillaries. These findings suggest that the hyper-permeability of the veins and/or capillaries that occurs after a certain latent period is one of the important factors in the pathogenesis of delayed radiation injury by carbon ions, the same as by X-rays. Radiation-induced functional disturbances of the endothelium and involvement of cytokines such as VEGF are suspected of being the cause of such vascular hyper-permeability.     

Multiple defects in the formation of rat cortical axonal pathways following prenatal X-ray irradiation

Prenatal X-ray irradiation is known to result in severe defects of neuronal migration and laminar formation in the cerebral cortex. We examined the formation of cortical afferent and efferent pathways in rats that had been exposed to X-ray irradiation (1.0 Gy) at embryonic day 14 (E14), by birthdating with bromodeoxyuridine (BrdU) and axonal labeling with 1-1'-dioctodecyl-3,3,3',3'- tetramethyl-indocarbocyanine perchlorate (DiI), in addition to immunohistochemical staining for various axonal markers including neurofilament, and cell adhesion molecules L1 and TAG-1. The results obtained were as follows. (i) The neuroepithelium formed germinal rosettes and concavities in the cortical anlage from 2 days after irradiation. Neurons generated in the neuroepithelium accumulated to form subcortical heterotopia and obstructed pathway formation in the intermediate zone, resulting in an aberrant trajectory of TAG-1-immunoreactive cortical efferent axons. (ii) In rats exposed to X-ray irradiation at E14, cystic cavities were formed in the cortex-striatum boundary region between E15 and E17, probably because of delayed cell death of neurons generated at E14. These cavities transiently interrupted both cortical afferent (L1-positive) and efferent (TAG-1-positive) axons. (iii) X-ray irradiation at E14 partially destroyed subplate neurons (transient targets of thalamic afferent axons) and disturbed the arrangement of the subplate layer. This resulted in a misrouting of neurofilament- and L1-immunoreactive thalamocortical axons that obliquely traversed the cortical plate to run up to the superficial layer. The present study demonstrates for the first time that X-ray irradiation during initial cortical development causes multiple defects in the formation of cortical afferent and efferent pathways.     

Trauma-induced alterations in cognition and Arc expression are reduced by previous exposure to 56Fe irradiation

Exposure to ionizing irradiation may affect brain functions directly, but may also change tissue sensitivity to a secondary insult such as trauma, stroke, or degenerative disease. To determine if a low dose of particulate irradiation sensitizes the brain to a subsequent injury, C56BL6 mice were exposed to brain only irradiation with 0.5 Gy of (56) Fe ions. Two months later, unilateral traumatic brain injury was induced using a controlled cortical impact system. Three weeks after trauma, animals received multiple BrdU injections and 30 days later were tested for cognitive performance in the Morris water maze. All animals were able to locate the visible and hidden platform during training; however, treatment effects were seen when spatial memory retention was assessed in the probe trial (no platform). Although sham and irradiated animals showed spatial memory retention, mice that received trauma alone did not. When trauma was preceded by irradiation, performance in the water maze was not different from sham-treated animals, suggesting that low-dose irradiation had a protective effect in the context of a subsequent traumatic injury. Measures of hippocampal neurogenesis showed that combined injury did not induce any changes greater that those seen after trauma or radiation alone. After trauma, there was a significant decrease in the percentage of neurons expressing the behaviorally induced immediate early gene Arc in both hemispheres, without associated neuronal loss. After combined injury there were no differences relative to sham-treated mice. Our results suggest that combined injury resulted in decreased alterations of our endpoints compared to trauma alone. Although the underlying mechanisms are not yet known, these results resemble a preconditioning, adaptive, or inducible-like protective response, where a sublethal or potentially injurious stimulus (i.e., irradiation) induces tolerance to a subsequent and potentially more damaging insult (trauma).     

Effects of prenatal irradiation on the development of cerebral cortex and corpus callosum of the mouse

Defects of the cerebral cortex and corpus callosum of mice subjected prenatally to gamma irradiation were evaluated as a function of dose and of embryonic age at irradiation. Pregnant mice were exposed to a gamma source at 16, 17, and 19 days of gestation (E16, E17, and E19, respectively), with total doses of 2 Gy and 3 Gy, in order to produce brain defects on their progeny. At 60 postnatal days, the brains of the offspring were analyzed qualitatively and quantitatively and compared with those of nonirradiated animals. Mice irradiated at E16 were all acallosal. Those that were exposed to 2 Gy displayed an aberrant longitudinal bundle typical of other acallosals, but this was not the case in those irradiated with 3 Gy. The corpus callosum of animals irradiated at E17 with 3 Gy was pronouncedly hypotrophic, but milder effects were observed in the other groups. Quantitative analysis confirmed a dependence of callosal midsagittal area upon dose and age at irradiation, and, in addition, indicated an interaction between these variables. The neocortex of irradiated animals was hypotrophic: layers II-III were much more affected than layer V, and this was more affected than layer VI. Quantitative analysis indicated that this effect also depended on dose and age at irradiation and that it was due to a loss of cortical neurons. Furthermore, a positive correlation was found between the number of neurons within layers II-III, and V and the midsagittal area of the corpus callosum. Ectopic neurons were found in the white matter and in layer I of animals irradiated at E16 and E17, indicating that fetal exposure to ionizing radiation interfered with the migration of cortical neuroblasts.     

体外培养大鼠皮质神经元机械性损伤后代谢型谷氨酸受体1a表达规律及其竞争性拮抗剂1-氨基茚满1，5-二羧酸的保护作用

体外培养大鼠皮质神经元机械性损伤模型,伤后30min,损伤神经元存活率较正常神经元明显下降,且随损伤程度加重神经元存活率随之降低。RT-PCR结果,显示神经元重度损伤1h后代谢型谷氨酸受体1a mRNA的表达明显升高。免疫组化染色发现神经元机械性损伤后30min,代谢型谷氨酸受体1a阳性细胞较正常神经元明显增多。伤后12h,1-氨基茚满1,5-二羧酸处理的损伤神经元乳酸脱氢酶活性较单纯损伤的神经元明显降低。伤后1h后1-氨基茚满1,5-二羧酸处理的损伤神经元较单纯损伤神经元细胞内Ca2 +浓度明显降低。提示皮质神经元机械性损伤后代谢型谷氨酸受体1a表达明显增强,创伤引起的神经细胞内游离Ca2 +浓度升高可被代谢型谷氨酸受体1a 拮抗剂1-氨基茚满1,5-二羧酸阻断,说明1-氨基茚满1,5-二羧酸有显著的神经保护作用。     

Temporal and egional profiles of cytoskeletal protein accumulation in the rat brain following traumatic brain injury

Abstract To characterize the cytoskeletal aberration due to traumatic injury, temporal and regional profiles of changes in immunoreactivity of microtubule-associated protein 2 (MAP2), neurofilament heavy subunit protein (NFH) and heat shock protein 72 (HSP72) were investigated after different magnitudes of traumatic brain injury by fluid percussion. The experimental rat brain was perfusion-fixed at 1, 6 and 24 hours after traumatic brain injury. Conventional histological staining has demonstrated that the mildest traumatic brain injury (1.0 atm) induced no neuronal loss at the impact site and that neuron loss was apparent when traumatic brain injury was increased to 4.3 atm. The mildest traumatic brain injury, however, caused a significant increase in HSP72 immunoreactivity in the superficial cortical layers at the impact site as early as 1 hour after the injury. In the case of severe traumatic brain injury (4.3 atm), neuron loss was apparent in the area at the impact site, but the increase in HSP72 immunoreactivity was moderate, and it was observed only after 6 hours in the deep cortical layers under the necrotic area. The increased immunostaining of MAP2 was demonstrated in damaged axons and neuronal perikarya in the wider area surrounding the impact site at 6 and 24 hours after the injury. Six and 24 hours after the injury, perikaryal accumulation of neurofilament was observed, and the accumulated neurofilament was mostly phosphorylated. These results indicate that the severe traumatic brain injury of 4.3 atm triggers the abnormal accumulation of cytoskeletal proteins in neuronal perikarya, most probably due to an impairment of axonal transport. It is implied that the increased expression of HSP72 may be involved in the protective process of neurons after traumatic brain injury.     

Kukoamine A Prevents Radiation-Induced Neuroinflammation and Preserves Hippocampal Neurogenesis in Rats by Inhibiting Activation of NF-κB and AP-1

Impaired hippocampal neurogenesis and neuroinflammation are involved in the pathogenesis of radiation-induced brain injury. Kukoamine A (KuA) was demonstrated to have neuroprotective effects through inhibiting oxidative stress and apoptosis after whole-brain irradiation (WBI) in rats. The aim of this study was to investigate whether administration of KuA would prevent radiation-induced neuroinflammation and the detrimental effect on hippocampal neurogenesis. For this study, male Wistar rats received either sham irradiation or WBI (30 Gy single dose of X-rays) followed by the immediate injection of either KuA or vehicle intravenously. The dose of KuA was 5, 10, and 20 mg/kg, respectively. The levels of pro-inflammatory cytokines were assayed by ELISA kits. The newborn neurons were detected by 5-bromo-2-deoxyuridine (BrdU)/neuronal nuclei (NeuN) double immunofluorescence. Microglial activation was measured by Iba-1 immunofluorescence. The expression of Cox-2 and the activation of nuclear factor κB (NF-κB), activating protein 1(AP-1), and PPARδ were evaluated by western blot. WBI led to a significant increase in the level of TNF-α, IL-1β, and Cox-2, and it was alleviated by KuA administration. KuA attenuated microglial activation in rat hippocampus after WBI. Neurogenesis impairment induced by WBI was ameliorated by KuA. Additionally, KuA alleviated the increased translocation of NF-κB p65 subunit and phosphorylation of c-jun induced by WBI and elevated the expression of PPARδ. These data indicate that KuA could ameliorate the neuroinflammatory response and protect neurogenesis after WBI, partially through regulating the activation of NF-κB, AP-1, and PPARδ.     

恶性脑胶质瘤立体定向加常规放疗的疗效观察(附32例临床分析)

目的探讨病理高级别胶质瘤术后,常规外照射加立体定向照射放疗推量治疗模式的疗效。方法对病理诊断均为WHOⅢ～Ⅳ级胶质瘤治疗后患者,放射治疗前程常规照射和后程立体定向照射推量相结合的方式,外照射46～50Gy23～25f/4.6～5W后,紧接着用分次立体定向照射推量14～20Gy。结果治疗后近期效果满意,无严重神经功能障碍并发症。本组病例1、2、3年总体生存率分别为77.3%、52.5%、25.0%;1、2、3年无进展生存率分别为59.8%、36.7%、16.3%。急性放射反应多为1～2级,没有发现4级以上急性放射反应。结论采用分次立体定向加常规放疗治疗胶质瘤既发挥了放射物理剂量分布的优点,又符合放射生物学原则,是控制高分级胶质瘤生长及延迟复发的重要辅助治疗手段。     

Binding partners L1 cell adhesion molecule and the ezrin-radixin-moesin (ERM) proteins are involved in development and the regenerative response to injury of hippocampal and cortical neurons

Regeneration of the adult central nervous system may require recapitulation of developmental events and therefore involve the re-expression of developmentally significant proteins. We have investigated whether the L1 cell adhesion molecule, and its binding partner, the ezrin-radixin-moesin (ERM) proteins are involved in the neuronal regenerative response to injury. Hippocampal and cortical neurons were cultured in vitro on either an L1 substrate or poly-L-lysine, and ERM and other neuronal proteins were localized immunocytochemically both developmentally and following neurite transection of neurons maintained in long-term culture. Activated ERM was localized to growth cones up to 7 days in vitro but relatively mature cultures (21 days in vitro) were devoid of active ERM proteins. However, ERM proteins were localized to the growth cones of sprouting neuronal processes that formed several hours after neurite transection. In addition, the L1 substrate, relative to poly-L-lysine, resulted in significantly longer regenerative neurites, as well as larger growth cones with more filopodia. Furthermore, neurons derived from the cortex formed significantly longer post-injury neurite sprouts at 6 h post-injury than hippocampal derived neurons grown on both substrates. We have demonstrated that L1 and the ERM proteins are involved in the neuronal response to injury, and that neurons derived from the hippocampus and cortex may have different post-injury regenerative neurite sprouting abilities.     

脑源性神经营养因子基因转染可促进弥漫性轴突损伤神经元修复和轴突再生

应用脂质体将外源脑源性神经营养因子基因导入弥漫性轴突损伤模型大鼠脑内,力图通过脑源性神经营养因子促进神经元再生及修复的作用,促进损伤大鼠的形态功能恢复。结果显示基因转染后弥漫性轴突损伤额叶皮质神经元的形态得到改善,额叶皮质组织神经丝蛋白表达增加,证实脑源性神经营养因子可促进弥漫性轴突损伤后神经元的修复及轴突的再生。     

Abdominal vagi mediate c-Fos expression induced by X-ray irradiation in the nucleus tractus solitarii of the rat

The mechanism of induction of emesis by X-ray irradiation remains largely unknown. The purpose of the present research was to clarify the neuronal basis of the induction of nausea induced by X-ray irradiation analyzing c-Fos expression in the nucleus tractus solitarii (NTS) as a marker of cellular excitation. We confirmed that the dose of X-ray irradiation (4 Gy) used for the present research could actually induce nausea by preliminary measurement of kaolin intake. Induction of c-Fos immunoreactivity in the NTS was observed in the animals that received X-ray irradiation of the whole body. The mean number of c-Fos positive cells in the animals that received irradiation was significantly larger than that in the non-irradiated animals. Partial exposure of the abdomen to X-rays showed significantly greater c-Fos expression than that of the head. These results indicated the presence of a certain route for transmitting information from the periphery toward the central nervous system by X-ray irradiation. The number of c-Fos positive cells induced by X-ray irradiation in animals vagotomized at the subdiaphragmatic level was lower than that in sham-operated animals. Animals receiving a serotonin subtype three (5-HT3, 5-hydroxytryptamine) receptor antagonist (tropisetron, ICS 205-930, 3-tropanyl-indole-3-carboxylate) showed a significant reduction in c-Fos protein expression compared to animals receiving a vehicle. These results strongly suggested that X-ray irradiation activates 5-HT3 receptors on the terminals of the abdominal vagal nerves to excite the afferent pathway, thereby inducing emesis.     

Neuronal injury and loss after traumatic brain injury: time course and regional variability

We have examined regional neuronal injury after traumatic brain injury using Fluoro-Jade, an acidic dye that exhibits a marked affinity for both the degenerating neuronal cell body and its processes and have determined the extent to which early injury corresponds to regional patterns of neuronal loss. Rats (n=45) were subjected to lateral fluid percussion brain injury and euthanized at 3 h to 28 days post injury. Complementary Fluoro-Jade, silver impregnation methods and TUNEL were used to assess neuronal injury. Neuronal loss was evaluated in sections immunostained for NeuN, a neuronal specific nuclear protein. Overt neuronal cell loss was evident by 7 days post injury in the cortex, hippocampus and thalamus. Injured neurons were apparent in the ipsilateral cortex bordering the impact site, hippocampus (CA1 and dentate), thalamus, and vermis of the cerebellum as early as 3 h post injury. Degenerating neurons were maximal by 1 and 3 days in the cortex and hippocampus, by 3 and 7 days in the cerebellum, and by 7 days in the thalamus. The regional distribution of Fluoro-Jade-labeled neurons corresponded to a similar pattern of silver and TUNEL staining. Together, these findings demonstrate a regionally specific temporal pattern of neuronal injury that results in overt neuronal cell loss within both cortical and subcortical regions.     

Synchrotron-generated microbeam radiosurgery: a novel experimental approach to modulate brain function

Synchrotron-generated X-ray microplanar beams (microbeams) are characterized by peculiar biological properties such as a remarkable tissue-sparing effect in healthy tissues including the central nervous system (CNS) and, as a direct consequence, the ability to deliver extremely high doses without induction of radionecrosis. Growing experimental evidence is showing remarkable tolerance of brain and spinal cord to irradiation with microbeam arrays delivering doses up to 400 Gy with a beam width up to 0·7 mm. Submillimetric beams can be delivered following a stereotactic design bringing to the target doses in the range of hundreds of Gray without harm to the surrounding tissues. Microbeam arrays can be used to generate cortical transections or subcortical lesions, thus enabling the non-invasive modulation of brain networks. This novel microradiosurgical approach is of great interest for the treatment of a variety of brain disorders, including functional diseases such as epilepsy and movement disorders.     

Effect of intensity-modulated radiation therapy on sciatic nerve injury caused by echinococcosis

Conventional radiotherapy has a good killing effect on femoral echinococcosis.However,the sciatic nerve around the lesion is irreversibly damaged owing to bystander effects.Although intensity-modulated radiation therapy shows great advantages for precise dose distribution into lesions,it is unknown whether intensity-modulated radiation therapy can perfectly protect the surrounding sciatic nerve on the basis of good killing of femoral echinococcosis foci.Therefore,this study comparatively analyzed differences between intensity-modulated radiation therapy and conventional radiotherapy on the basis of safety to peripheral nerves.Pure-breed Meriones meridiani with bilateral femoral echinococcosis were selected as the research object.Intensity-modulated radiation therapy was used to treat left femoral echinococcosis of Meriones meridianus,while conventional radiotherapy was used to treat right femoral echinococcosis of the same Meriones meridianus.The total radiation dose was 40 Gy.To understand whether intensity-modulated radiation therapy and conventional radiotherapy can kill femoral echinococcosis,trypan blue staining was used to detect pathological changes of bone Echinococcus granulosus and protoscolex death after radiotherapy.Additionally,enzyme histochemical staining was utilized to measure acid phosphatase activity in the protoscolex after radiotherapy.One week after radiotherapy,the overall structure of echinococcosis in bilateral femurs of Meriones meridiani treated by intensity-modulated radiation therapy disappeared.There was no significant difference in the mortality rate of protoscoleces of Echinococcus granulosus between the bilateral femurs of Meriones meridiani.Moreover,there was no significant difference in acid phosphatase activity in the protoscolex of Echinococcus granulosus between bilateral femurs.To understand the injury of sciatic nerve surrounding the foci of femoral echinococcosis caused by intensity-modulated radiation therapy and conventional radiotherapy,the ultrastructure of sciatic nerves after radiotherapy was observed by transmission electron microscopy.Additionally,apoptosis of neurons was examined using a terminaldeoxynucleotidyl transferase-mediated d UTP nick end labeling assay,and expression of Bcl-2 and Bax in sciatic nerve tissue was detected by immunohistochemical staining and western blot assay.Our results showed that most neurons in the left sciatic nerve of Meriones meridiani with echinococcosis treated by intensity-modulated radiation therapy had reversible injury,and there was no obvious apoptosis.Compared with conventional radiotherapy,the number of apoptotic cells and Bax expression in sciatic nerve treated by intensity-modulated radiation therapy were significantly decreased,while Bcl-2 expression was significantly increased.Our findings suggest that intensity-modulated radiation therapy has the same therapeutic effect on echinococcosis as conventional radiotherapy,and can reduce apoptosis of the sciatic nerve around foci caused by radiotherapy.Experiments were approved by the Animal Ethics Committee of People's Hospital of Xinjiang Uygur Autonomous Region,China(Approval No.20130301A41) on March 1,2013.     

Down-regulation of Homer1b/c expression protects cultured neurons after traumatic injury

Activation of metabotropic glutamate receptor 1a aggravates traumatic brain injury. The constitutively expressed protein Homer1b/c participates in delivering and anchoring metabotropic glutamate receptors in neurons. Here, we aimed to verify whether down-regulation of Homer1b/c by RNA interference could protect cultured rat cortical neurons from traumatic injury. We showed that 36 hours after transfection of Homer1b/c small interfering RNA, metabotropic glutamate receptor 1a was present only in the neuronal cytoplasm, but not in the dendrites. Calcium fluorescence intensity was also decreased significantly. Moreover, lactate dehydrogenase concentration was significantly decreased in Homer1b/c small interfering RNA-transfected cells compared with that in untransfected and control small interfering RNA-transfected cells 24 hours after traumatic neuronal injury.Our findings indicate that down-regulation of Homer1b/c could reduce metabotropic glutamate receptor 1a transfer from the cell body to the dendrite, relieve calcium overload, and protect neurons from traumatic injury.     

神经元机械性损伤后Homer蛋白表达及意义

目的研究体外培养神经元机械损伤后不同亚型Homer蛋白表达的变化规律,进一步阐明Homer与神经元损伤的关系.方法胎鼠脑皮质神经元体外培养7 d,以微量移液器塑料滴头划割培养的神经元,横、竖各划8道,划伤宽度约1 mm,造成机械性损伤.在伤后不同时间(10、30 min,1、3、6、12、24、72 h),采用链酶亲合素-过氧化物酶复合物法(SABC法)行免疫组化染色.对照组不进行机械性划割,其它处理同损伤组.结果对照组神经元在各时间点Homer 1a免疫组化染色呈弱阳性.机械性损伤后从伤后10 min持续至24 h Homer 1a表达量增加,免疫组化染色呈阳性.阳性染色呈颗粒状分布于胞浆、胞膜及突起.Homer 1b/c,Homer 2a/b和Homer 3在对照组神经元中即有一定程度表达,机械性损伤后,其表达量无明显变化.结论神经元机械性损伤后Homer 1a表达明显升高,而Homer 1b/c、2a/b和3表达无明显变化. Homer 1a对第1组代谢型谷氨酸受体(mGluR)的功能具有负反馈作用,Homer 1b/c、2a/b和3则调节mGluR在细胞表面的分布,提高其稳定性.据此推测,增加Homer 1a表达或减少Homer 1b/c、2a/b和3的表达可能改变mGluR受体信号的传递效率,对神经元具有保护作用.     

Radiation-induced,lamina-specific deletion of neurons in the primate visual cortex

To examine the early determinants of cortical cytoarchitecture, we deleted specific neuronal classes in the primate visual cortex by ionizing irradiation at selected prenatal stages. Multiple doses of X-rays were delivered to the macaque monkey brain between embryonic day (E) 80 and E90 to block the division of cells destined to populate the superficial cortical layers, between E70 and E79 to eliminate neurons destined for the middle layers; and between E33 and E40 to delete neurons destined for the lateral geniculate nucleus (LGN) that project to the cortex. All animals were killed after birth, and their brains were processed for histological and electron microscopic analyses. Cell density and number in the LGN and visual cortex were determined by using three-dimensional, computer-aided morphometry. In animals irradiated with low doses (total of ∼200 cGy) during the genesis of the LGN but before the onset of corticogenesis (E33-40), the LGN was reduced in both volume and number of neurons. Area 17 in these animals displayed only slight changes in cortical thickness, cell density, and area-specific cytoarchitectonic features, whereas the total surface devoted to area 17 was significantly diminished. In contrast, animals irradiated with low doses during the period of corticogenesis, after the completion of the LGN genesis, showed no significant change in the volume of the LGN or in the number of its cells. Moreover, in these animals, the surface of area 17 was not significantly altered, although the cortical layers generated at the time of irradiation had a significantly lower density and total number of cells, whereas the layers generated before and after the period of irradiation were spared. In contrast, cases exposed to high doses of X-ray (total > 300 cGy) showed more severe effects, including all layers. However, layers normally generated during irradiation were depleted and consisted of cell-sparse strata populated by densely packed neuropil (axons, small dendrites, dendritic spines, and synaptic boutons). These cell-sparse strata were situated deeper in the early irradiated animals than in the later irradiated animals, and their laminar position changed abruptly at the area 17/18 border. These results show that low doses of irradiation in a slowly developing primate brain can be used effectively to eliminate targeted classes of neurons before they reach their final position, providing an opportunity to examine the role of cell-cell interactions in the formation of circuitry and the role of specific cell classes in cortical development. J. Comp. Neurol. 381:335-352, 1997. © 1997 Wiley-Liss, Inc.     

The calmodulin-dependent protein kinase II inhibitor KN-93 protects rat cerebral cortical neurons from N-methyl-D-aspartic acid-induced injury

In this study, primary cultured cerebral cortical neurons of Sprague-Dawley neonatal rats were treated with 0.25, 0.5, and 1.0 μM calmodulin-dependent protein kinase II inhibitor KN-93 after 50 μM N-methyl-D-aspartic acid-induced injury. Results showed that, compared with N-methyl-D-aspartic acid-induced injury neurons, the activity of cells markedly increased, apoptosis was significantly reduced, leakage of lactate dehydrogenase decreased, and intracellular Ca(2+) concentrations in neurons reduced after KN-93 treatment. The expression of caspase-3, phosphorylated calmodulin-dependent protein kinase II and total calmodulin-dependent protein kinase II protein decreased after KN-93 treatment. And the effect was apparent at a dose of 1.0 μM KN-93. Experimental findings suggest that KN-93 can induce a dose-dependent neuroprotective effect, and that the underlying mechanism may be related to the down-regulation of caspase-3 and calmodulin-dependent protein kinase II expression.