Reestablishment of the blood brain barrier to peroxidase following cold injury to mouse cortex

Summary Following the induction of cold lesions in the parietal cortex of mice, i.v. injected horse radish peroxidase (HRP) was used to investigate the blood-brain barrier of the intracerebral vessels to this protein.During the first week the majority of the arterioles and capillaries within the necrotic zone of the lesion had leaked HRP into the brain parenchyma. The capillaries in the peripheral zone were surrounded by swollen astrocyte end feet but HRP was confined to vesicles within the endothelial cell cytoplasm. Small arterioles (10–20 m diameter) in the peripheral zone were observed leaking HRP and the reaction product was observed in the perivascular basement membranes and in vesicles within the endothelial cell cytoplasm.During the 2nd and 3rd weeks the regenerating capillaries which grew into the previously necrotic zone from the periphery revealed no evidence of leakage of HRP. Several non-patent regenerating capillaries were also observed at this time but by the 4th week all capillaries contained HRP within their lumen. The small arterioles in the peripheral zone continued to leak peroxidase throughout the period of the study. In the 2nd week approximately 10% of the arterioles examined were leaking HRP but by the 4th week only 2 out of 53 arterioles were involved.The possibility that the impaired BBB function of the small arterioles is due to an absence of a sympathetic innervation or to raised levels of serotonin is considered.     

Elevated immunoreactivity for glutamic acid decarboxylase in the rat cerebral cortex following transient middle cerebral artery occlusion

We investigated the expression of glutamic acid decarboxylase (molecular weight 67,000; GAD67) immunohistochemically in the rat cerebral cortex following transient middle cereral artery occlusion (MCAO) capable of producing slowly progressive neuronal damage. An increase in GAD67 immunoreactivity was observed in the cerebral cortex ipsilateral to the ischemic insult, most prominent in lamina IV, 3 to 14 days after MCAO. At this stage, light microscopy showed GAD67-positive puncta to be larger and more strongly immunoreactive in the ipsilateral cortex than those in the contralateral side. The elevated expression of GAD67 in the insulted cortex may reflect part of the adaptive functional changes in GABA transmission with slowly progressive cortical ischemic damage.Supported in part by Grant-in-Aid for Scientific Research from the Ministry of Education, Science and Culture of Japan     

术中B超联合神经导航辅助显微手术切除脑功能区及脑深部病变

目的 探讨术中B超联合神经导航在大脑皮层功能区及脑深部病变切除术中的应用价值.方法 回顾性分析2017年12月至2020年12月收治的25例(32个病灶)大脑皮层功能区及深部病变的临床资料.均在术中B超联合神经导航引导下切除病变.结果 术中B超均完整、清晰显示32个病灶,其中29个皮层功能区病灶,术中B超定位与MRI神...     

Alteration of GABA transporter expression in the rat cerebral cortex following needle puncture and colchicine injection

In the adult cerebral cortex, GABA transporters (GATs) are expressed by both neurons and astrocytes. GAT-1 immunoreactivity is found in axon terminals of GABAergic neurons and astrocytes, while GAT-3 immunolabeling occurs only in the latter. The present study was designed to determine whether the expression of GAT-1 and GAT-3 in the adult rat cerebrum changes after needle lesion and colchicine infusion. Following a needle puncture or a saline injection, immunolabeling for GAT-1 and GAT-3 was slightly increased in an area around the needle track. Not only was the neuropil labeling for both GATs increased, but also a few neuronal somata were found to be immunoreactive for GAT-1. Colchicine injections induced a striking increase in immunolabeling for both GATs in the neuropil in an area adjacent to the needle path and surrounding it. A homologous region of the contralateral hemisphere also showed a moderate increase of immunoreactivity in the neuropil for both GATs. Furthermore, this contralateral site showed many neuronal somata immunolabeled for GAT-1. These changes were mainly detected during the first 5 days following intracortical lesions. These results indicate that (1) the upregulation of GAT-1 and GAT-3 in cortical interneurons and astrocytes is caused by both mechanical and chemical factors associated with the injections; (2) increased GAT-1 and GAT-3 expression contralateral to the site of colchicine injection is mediated by transcellular signaling across the corpus callosum; and (3) the lesion-induced GAT expression may play a protective role by helping to balance excitatory and inhibitory neuronal activities.     

The genomic profile of the cerebral cortex after closed head injury in mice: effects of minocycline

Microarray analysis was used to delineate gene expression patterns and profile changes following traumatic brain injury (TBI) in mice. A parallel microarray analysis was carried out in mice with TBI that were subsequently treated with minocycline, a drug proposed as a neuroprotectant in other neurological disorders. The aim of this comparison was to identify pathways that may be involved in secondary injury processes following TBI and potential specific pathways that could be targeted with second generation therapeutics for the treatment of neurotrauma patients. Gene expression profiles were measured with the compugen long oligo chip and real-time PCR was used to validate microarray findings. A pilot study of effect of minocycline on gene expression following TBI was also carried out. Gene ontology comparison analysis of sham TBI and minocycline treated brains revealed biological pathways with more genes differentially expressed than predicted by chance. Among 495 gene ontology categories, the significantly different gene ontology groups included chemokines, genes involved in cell surface receptor-linked signal transduction and pro-inflammatory cytokines. Expression levels of some key genes were validated by real-time quantitative PCR. This study confirms that multiple regulatory pathways are affected following brain injury and demonstrates for the first time that specific genes and molecular networks are affected by minocycline following brain injury. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Stages of axonal regeneration following optic nerve crush in goldfish: contrasting effects of conditioning nerve lesions and intraocular acetoxycycloheximide injections

The progress of axonal outgrowth after a crush lesion of the goldfish optic nerve can be determined by examining longitudinal silver-stained sections at selected intervals. The outgrowth of leading axons proceeded at 0.46 mm/day after an initial delay of 4.2 days. Outgrowth can be rapidly characterized by differentiating among a series of qualitatively different stages. In the sprouting (S) phase of regeneration, stage S1 is defined by the presence of isolated axonal sprouts reaching into the crush zone, and stage S2 by bundles of sprouts in the crush zone. In the elongation (E) phase of regeneration, stage E1 is defined by bundles that bridge the crush zone, stage E2 by bundles that reach the optic chiasm, and stage E3 by bundles that reach the level of the hypothalamus. During normal regeneration, stage E2 was attained 7-9 days after the crush (testing lesion), and stage E3 at 11 days. However, if the testing lesion had been preceded by a similar (conditioning) lesion 2 weeks earlier, stage E2 was reached at 3 days and stage E3 at 5 days. Conversely, when a protein synthesis inhibitor (acetoxycycloheximide) was injected into the right eye daily from the 5th through 9th day after a testing lesion, the injected side lagged 1-2 stages behind the contralateral control side in nerves examined on the 10th day.     

成年哺乳动物中枢神经系统损伤后神经元轴突再生的调节

成年哺乳动物中枢神经系统损伤后修复十分困难，常导致严重的持续性神经功能障碍，因此中枢神经系统损伤修复的研究成为当今热点。最新研究证明，中枢神经系统神经元轴突冉生障碍不是因为其内在的再牛能力不足，而是与受伤神经元所处的状态及生长环境有关。调节损伤神经元轴突再生至少应该包括如下步骤：维持神经元存活并处于一种生长状态，防止胶质瘢痕形成，清除存在于髓鞘碎片间的神经再生阻滞因子及指引轴突再生方向。本文对近年来有关成年哺乳动物中枢神经系统神经元轴突再生及其调节的研究成果进行综述。     

Glial changes in primate cerebral cortex following long-term sensory deprivation

Significant morphological modifications in the layout of primate-specific (interlaminar) astroglia were found in somatosensory areas 3a, 3b, 1 and 2 eleven to thirteen months after transection of the posterior spinal cord in adult Macaca monkeys. These observations plus lack of evidence of a persistent reactive astrocytosis suggest that changes in the spatial arrangement of interlaminar glia may be an integral part of the long-term process of structural reorganization of the cerebral cortex following cortical deafferentation.     

Impulse magnetic stimulation facilitates synaptic regeneration in rats following sciatic nerve injury

The current studies describing magnetic stimulation for treatment of nervous system diseases mainly focus on transcranial magnetic stimulation and rarely focus on spinal cord magnetic stimula-tion.Spinal cord magnetic stimulation has been confirmed to promote neural plasticity after injuries of spinal cord,brain and peripheral nerve.To evaluate the effects of impulse magnetic stimulation of the spinal cord on peripheral nerve regneration,we compressed a 3 mm segment located in the middle third of the hip using a sterilized artery forceps to induce ischemia.Then,all animals un-derwent impulse magnetic stimulation of the lumbar portion of spinal crod and spinal nerve roots daily for 1 month.Electron microscopy results showed that in and below the injuryed segment,the inflammation and demyelination of neural tissue were alleviated,apoptotic cells were reduced,and injured Schwann cells and myelin fibers were repaired.These findings suggest that high-frequency impulse magnetic stimulation of spinal cord and corresponding spinal nerve roots promotes synaptic regeneration following sciatic nerve injury.     

Melatonin reduces traumatic brain injur y-induced oxidative stress in the cerebral cortex and blood of rats

Free radicals induced by traumatic brain injury have deleterious effects on the function and antioxidant vitamin levels of several organ systems including the brain. Melatonin possesses antioxidant effect on the brain by maintaining antioxidant enzyme and vitamin levels. We investigated the effects of melatonin on antioxidant ability in the cerebral cortex and blood of traumatic brain injury rats. Results showed that the cerebral cortex β-carotene, vitamin C, vitamin E, reduced glutathione, and erythrocyte reduced glutathione levels, and plasma vitamin C level were decreased by traumatic brain injury whereas they were increased following melatonin treatment. In conclusion, melatonin seems to have protective effects on traumatic brain injury-induced cerebral cortex and blood toxicity by inhibiting free radical formation and supporting antioxidant vitamin redox system.     

Behavioral and morphological alterations following neonatal excitotoxic lesions of the medial prefrontal cortex in rats

The prefrontal cortex (PFC) is essential for executive functions in mammals. Damage of the developing PFC may partly be compensated over time, but may also lead to structural and functional deficits due to neurodevelopmental disturbances. The present study investigated the effects of excitotoxic lesions of the medial PFC (mPFC) in neonatal rats on brain morphology, myelination and behavior. Neonatal lesions were induced with ibotenate on postnatal day (pd) 7 and all animals were tested pre- and postpubertally for prepulse inhibition (PPI) of the acoustic startle reflex (ASR), locomotor activity and food preference. Furthermore, adult rats were tested for apomorphine sensitivity of PPI and for their performance in a progressive ratio operant response task. Neonatally lesioned animals showed a reduced volume of the mPFC, enlarged ventricles and a deficient myelination in some projection areas of the mPFC, including the thalamus, hippocampus, nucleus accumbens (NAC) and amygdala. PPI was enhanced in lesioned rats when tested as juveniles, but PPI-deficits induced by the dopamine receptor agonist apomorphine were exacerbated in adult rats after neonatal mPFC lesion. Furthermore, the break point in a progressive ratio task was lower in lesioned animals, whereas the total number of lever presses was initially increased, indicating an impulsive response of rats for food reward under a progressive ratio schedule after neonatal mPFC lesion. No effects were found on food preference and open field performance. These data support the hypothesis that neonatal mPFC lesions lead to disruptions of neurodevelopmental processes in a cortico-limbic-striatal network, which are manifested in adult animals as morphological and behavioral disturbances.     

A new model for quantification of microvascular regeneration after a lesion of the rat cerebral cortex

The purpose of this study is to validate a method for the quantification of the neovascularization in the vicinity of a lesion made in the cerebral rat cortex. A cavity, made by aspiration in the occipital cortex of young rats, induces around the lesion a parenchymal and vascular reaction. The parenchymal reaction is characterized by cellular necrosis and gliosis. The vascularization is more dense around the cavity than in normal cortex. Morphometric analysis indicates, 8 days after the lesion, a 130% increase of the total length of the vessels in comparison to the contralateral normal cortex.     

Rhesus monkey neural stem cell transplantation promotes neural regeneration in rats with hippocampal lesions

Rhesus monkey neural stem cells are capable of differentiating into neurons and glial cells.Therefore,neural stem cell transplantation can be used to promote functional recovery of the nervous system.Rhesus monkey neural stem cells(1×105 cells/μL) were injected into bilateral hippocampi of rats with hippocampal lesions.Confocal laser scanning microscopy demonstrated that green fluorescent protein-labeled transplanted cells survived and grew well.Transplanted cells were detected at the lesion site,but also in the nerve fiber-rich region of the cerebral cortex and corpus callosum.Some transplanted cells differentiated into neurons and glial cells clustering along the ventricular wall,and integrated into the recipient brain.Behavioral tests revealed that spatial learning and memory ability improved,indicating that rhesus monkey neural stem cells noticeably improve spatial learning and memory abilities in rats with hippocampal lesions.     

High-resolution 3D MRI of mouse brain reveals small cerebral structures in vivo

This work demonstrates technical approaches to high-quality magnetic resonance imaging (MRI) of small structures of the mouse brain in vivo. It turns out that excellent soft-tissue contrast requires the reduction of partial volume effects by using 3D MRI at high (isotropic) resolution with linear voxel dimensions of about 100–150 μm. The long T₂* relaxation times at relatively low magnetic fields (2.35 T) offer the benefit of a small receiver bandwidth (increased signal-to-noise) at a moderate echo time which together with the small voxel size avoids visual susceptibility artifacts. For measuring times of 1–1.5 h both T₁-weighted (FLASH) and T₂-weighted (Fast Spin-Echo) 3D MRI acquisitions exhibit detailed anatomical insights in accordance with histological sections from a mouse brain atlas. Preliminary applications address the identification of neuroanatomical variations in different mouse strains and the use of Mn²⁺ as a T₁ contrast agent for neuroaxonal tracing of fiber tracts within the mouse visual pathway.     

Monoclonal antibody, KK1, recognizes human retinal astrocytes and distinguishes a subtype of astrocytes in mouse brain

Astrocytes exhibit a diverse morphology and numerous functions in the central nervous system as well as in the retina. In order to obtain markers for the analysis of astrocytes, we prepared monoclonal antibodies that recognized antigens specific to astrocytes. Monoclonal antibody (mAb), designated KK1, reacted with the processes of astrocytes in the nerve fiber layer and the ganglion cell layer in the human retina as detected by indirect immunofluorescence. Normal Müller cells, whose processes are localized vertically in retina, were not labeled by KK1 mAb. In mouse brain, KK1 mAb reacted specifically with astrocytes in the white matter, but not with those in the gray matter. Studies employing a high-resolution confocal laser scanning microscope and double-labeling with KK1 mAb and commercially available anti-glial fibrillary acidic protein (GFAP) mAb (GA5) revealed that KK1 mAb visualized the processes that were not recognized by anti-GFAP rnAb (GA5) in both human retina and mouse brain. In cultured mouse astrocytes. KKI mAb reacted only with anti-GFAP mAb (GA5)-positive cells, but a small percentage of anti-GFAP mAb (GA5)-positive cells were labeled with KK1 mAb. In addition, the subcellular distribution of the KK1 antigen in cultured astrocytes apparently differed from that of GFAP labeled by anti-GFAP mAb (GA5). The antigen that was purified from the normal mouse brain by KK1 mAb-conjugated beads reacted with anti-GFAP mAb(GA5) in immunoblotting. No reactivity of KK1 mAb was observed in immunohistochemical analysis in GFAP − / − mutant mouse brain. These results demonstrate that KK1 mAb specifically recognized an epitope of GFAP that did not react with other anti-GFAP mAb (GA5). Retinal astrocytes and a subtype of astrocytes in the white matter of mouse brain shared the epitope that was recognized by KKI mAb. KKI mAb might be a powerful tool to investigate a subtype of astrocytes.     

Mechanisms of enhancement of neurite regeneration in vitro following a conditioning sciatic nerve lesion

To examine the mechanisms responsible for the more rapid nerve regeneration observed after a previous (conditioning) nerve injury, adult rats were subjected to a midthigh sciatic nerve transection by using one of three protocols designed to facilitate or restrict nerve regeneration: 1) ligation, in which transected axons were prevented from regenerating; 2) cut, in which transected axons were permitted to extend into peripheral target tissue but were separated from the denervated peripheral nerve stump; and 3) crush, in which axons could regenerate normally through the denervated distal nerve tract. The affected dorsal root ganglia (DRG) were subsequently removed, dissociated, and cultured for up to 3 days, and the timing of neurite initiation, rate of outgrowth, and arborization pattern of previously injured neurons were compared with control DRG. Our results indicate that conditioning lesions have at least four distinct and differentially regulated effects on neuronal morphogenesis: 1) conditioning lesions promote earlier neurite initiation, 2) prior nerve injury decreases the ability of neurons to extend long neurites following a second axotomy, 3) exposure to the environment of a denervated peripheral nerve stimulates greater initial rates of neurite outgrowth, and 4) conditioning lesions reduces initial neuritic branching frequency, resulting in straighter neurites whose growth cones extend further distances from their cell bodies. The primary effect of all conditioning lesions on cultured DRG neurons appeared to be to advance the timing of morphogenesis, resulting in conditioning-lesioned neurons that exhibited characteristics consistent with control neurons that had been cultured for an additional day or more. A secondary effect of conditioning lesions on neurite outgrowth rates was dependent on the local environment of the axons prior to culturing. J. Comp. Neurol 391:11–29, 1998. © 1998 Wiley-Liss, Inc.     

Microglial reactions following thermal necrosis of the rat cortex: An electron microscope study

Summary The ultrastructural appearances of microglia in the rat cerebral cortex were examined following experimental cold lesions. It was found that microglia toop up extravascularized plasma by pinocytosis. These pinocytotic vesicles coalesced to form large vacuoles of medium electron density, which subsequently decreased in size and increased in density and morphological complexity. Concurrently the microglial cells underwent dedifferentiation and division. Between 3 and 7 days after making the cold lesion it was difficult to distinguish between phagocytes of microglial and haematogenous origin. The relationship of microglia to haematogenous phagocytes is discussed.This work was carried out at the M.R.C. Research Group in Applied Neurobiology, Institute of Neurology, Queens Square, London.     

成年哺乳动物中枢神经系统损伤后神经元轴突再生的调节

成年哺乳动物中枢神经系统损伤后修复十分困难,常导致严重的持续性神经功能障碍,因此中枢神经系统损伤修复的研究成为当今热点.最新研究证明,中枢神经系统神经元轴突再生障碍不是因为其内在的再生能力不足,而是与受伤神经元所处的状态及生长环境有关.调节损伤神经元轴突再生至少应该包括如下步骤:维持神经元存活并处于一种生长状态,防止胶质瘢痕形成,清除存在于髓鞘碎片间的神经再生阻滞因予及指引轴突再生方向.本文对近年来有关成年哺乳动物中枢神经系统神经元轴突再生及其调节的研究成果进行综述.     

An electrophysiological study of early retinotectal projection patterns during regeneration following optic nerve crush inside the cranium in Hyla moorei

The sequence of regeneration following intracranial optic nerve crush has been studied using electrophysological visual mapping in the frog Hyla moorei. Compared to our earlier series⁹ with extracranial crush, the time course was slower and the intermediate projections more disorganized. It is suggested that the apparent discrepancy between the early patterns of regeneration in Xenopus⁴ and Rana^5,6 compared to Hyla⁹, fish⁸ and newt², is not due to species differences but to the location of the lesion site.     

Reconstruction of the human cerebral cortex robust to white matter lesions: Method and validation

Cortical atrophy has been reported in a number of diseases, such as multiple sclerosis and Alzheimer's disease, that are also associated with white matter (WM) lesions. However, most cortical reconstruction techniques do not account for these pathologies, thereby requiring additional processing to correct for the effect of WM lesions. In this work, we introduce CRUISE⁺, an automated process for cortical reconstruction from magnetic resonance brain images with WM lesions. The process extends previously well validated methods to allow for multichannel input images and to accommodate for the presence of WM lesions. We provide new validation data and tools for measuring the accuracy of cortical reconstruction methods on healthy brains as well as brains with multiple sclerosis lesions. Using this data, we validate the accuracy of CRUISE⁺ and compare it to another state‐of‐the‐art cortical reconstruction tool. Our results demonstrate that CRUISE⁺ has superior performance in the cortical regions near WM lesions, and similar performance in other regions. Hum Brain Mapp 35:3385–3401, 2014. © 2013 Wiley Periodicals, Inc .