Expression and Prognostic Significance of p53 in Glioma Patients: A Meta-analysis

Neurochemical Research - Glioma is a brain tumor deriving from the neoplastic glial cells or neuroglia. Due to its resistance to anticancer drugs and different disease progress of individuals,...     

The triboluminescence of the blood and the brain cellular elements in rats exposed to X irradiation in doses causing bone marrow, intestinal and cerebral syndromes]

Triboluminescence of blood and brain cells (neurons and neuroglia) in bone marrow, intestinal and cerebral radiation syndromes has been investigated. Dynamics of triboluminescence intensity of neurons and glial cells after irradiation (0.013, 0.31 and 3.87 C/kg) is the same with that of blood triboluminescence.     

Neuroglial Roots of Neurodegenerative Diseases?

Neuroglia is critically important for controlling the brain homeostasis and for mounting the brain defence against pathological insults. Here, we overview recent data about the role of neuroglia in various types of neurodegenerative diseases (Alzheimer’s disease, Parkinson’s disease, fronto-temporal dementia, Wernicke encephalopathy, amyotrophic lateral sclerosis and immunodeficiency virus-1-associated dementia). In all these forms of neurodegeneration, astroglia undergoes complex morphological and functional changes. The early and mid-term stages of neurodegenerative processes, and specifically of Alzheimer’s disease, are associated with generalised atrophy of astroglia, whereas the later stages are characterised with an astrogliosis and microglial activation linked to neuropathological lesions such as senile plaques. Atrophic changes in astroglia may contribute to the initial cognitive deficits due to reduced glial synaptic coverage and decreased neuroprotection.     

The Role of NG2 Proteoglycan in Glioma

Neuron glia antigen-2 ((NG2), also known as chondroitin sulphate proteoglycan 4, or melanoma-associated chondroitin sulfate proteoglycan) is a type-1 membrane protein expressed by many central nervous system (CNS) cells during development and differentiation and plays a critical role in proliferation and angiogenesis. ‘NG2’ often references either the protein itself or the highly proliferative and undifferentiated glial cells expressing high levels of NG2 protein. NG2 glia represent the fourth major type of neuroglia in the mammalian nervous system and are classified as oligodendrocyte progenitor cells by virtue of their committed oligodendrocyte generation in developing and adult brain. Here, we discuss NG2 glial cells as well as NG2 protein and its expression and role with regards to CNS neoplasms as well as its potential as a therapeutic target for treating childhood CNS cancers.     

A comparative investigation of neuroglia in representative vertebrates: a silver carbonate study

The phylogenetic development of neuroglia (astrocytes, oligodendrocytes) was investigated in homologous cortical and subcortical forebrain regions of selected vertebrates. Microglia were not considered in the current study. Four to seven brains from each species were used. Scharenberg's modification for astroglia of del Rio Hortega's silver carbonate technique was used. The analysis of neuroglia cells was based on (1) the characteristic cellular morphology found in each species, (2) a comparison of the selected regions in each animal, (3) the interrelationships of astrocytes and their relations to neurons, blood vessels, and oligodendrocytes. The predominant type of neuroglia found in the fish, frog, and lizard was the ependymal cell; however, non-ependymal glial cells were also present. The bird represented a transitional phylogenetic stage from a predominance of ependymal glial to a predominance of non-ependymal glia. A progressive increase in the morphological relationships of glial cell bodies and processes to neurons was found with ascension of the phylogenetic scale from fish through primate. Interrelations were observed between adjacent astrocytic processes and cell bodies, and between astrocytes and oligodendrocytes. The processes of adjacent glial cells also appeared to show an increase in thickness at the point of approximation. A variety of astrocytes were observed ranging from small, round-oval shaped cells to large polygonal or stellate forms. Variations in the number of astrocytic processes, their thickness, and degree of secondary branching were described, and their possible functional significance was discussed.     

Neuron/glia relationships observed over intervals of several months in living mice

Identified neurons and glial cells in a parasympathetic ganglion were observed in situ with video-enhanced microscopy at intervals of up to 130 d in adult mice. Whereas the number and position of glial cells associated with particular neurons did not change over several hours, progressive differences were evident over intervals of weeks to months. These changes involved differences in the location of glial nuclei on the neuronal surface, differences in the apparent number of glial nuclei associated with each neuron, and often both. When we examined the arrangement of neurons and glial cells in the electron microscope, we also found that presynaptic nerve terminals are more prevalent in the vicinity of glial nuclei than elsewhere on the neuronal surface. The fact that glial nuclei are associated with preganglionic endings, together with the finding that the position and number of glial nuclei associated with identified neurons gradually changes, is in accord with the recent observation that synapses on these neurons are normally subject to ongoing rearrangement (Purves, D., J. T. Voyvodic, L. Magrassi, and H. Yawo. 1987. Science (Wash. DC). 238:1122-1126). By the same token, the present results suggest that glial cells are involved in synaptic remodeling.     

The short-term and long-lasting changes in DNA and RNA synthesis in the cerebral cortex cells of animals subjected to hypoxia and nerve tissue transplantation]

The DNA and RNA synthesis in the cells of the brain cortex of intact rats and animals subjected to hypoxia, hypoxia with subsequent transplantation or by the local brain injury has been investigated. The DNA synthesis changes insignificantly in the case of hypoxia, it enhances slightly in the area of the injury and increases much more after transplantation. The RNA synthesis decreases considerably immediately after hypoxia and decreases much more 120 days later. Using the ultracentrifuge method it has been found that under the effect of hypoxia the number of nervous cells decreases, the number of glial cells does not change. The local injury in the nervous tissue enhances abruptly the synthesis in neurons and glial cells in the hypoxia-exposed animals, the embryonic nervous tissue transplantation normalizes the number of neurons in the specimens under study and the RNA synthesis in the neurons and glial cells.     

Biochemical and morphological changes in the neuroglia in experimental herpetic encephalitis

The complex virological, biochemical and morphological study permitted to obtain various characteristics of mice herpes encephalitis. The reaction of astrocyte glia at different stages of herpes encephalitis was revealed and analyzed in detail. New data on the dynamics of desoxyribonuclease activity changes in neuroglia and the glial complex formation were obtained. It was shown that the increased DNA-ase activity in neuroglia and the astrocyte activation which morphological manifestation was the formation of glial complexes, may be referred to as processes dealing with barrier and elimination neuroglia functions in herpes encephalitis. The results presented allows to suppose that the severity of the development and outcome of herpes encephalitis mainly depends on the astrocyte glia condition, its potential abilities in appearing of barrier and eliminative functions.     

星形胶质细胞的生物学功能

人类大脑由两类细胞组成:一类是神经元,另一类是神经胶质细胞。神经胶质细胞的数量约为神经元的10倍,但其作用长期以来一直被认为仅限于在神经元之间充当填充物,填满大脑中的剩余空间,同时为神经元提供营养。但近年来认识到神经胶质细胞的主要成员星形胶质细胞能够感知外界刺激,它的反应选择性甚至高于相邻神经元。神经元的反应活动很多都要经过星形胶质细胞的介导才能完成。本文介绍了星形胶质细胞在神经调制、突触调节和神经血管系统偶联方面的一些新进展,以期在不久的将来对星形胶质细胞的功能有更深入的了解,并能应用于临床实践。     

电磁脉冲辐照大鼠海马区细胞凋亡与形态学变化

以体外原代培养的大鼠海马神经元和Wistar大鼠为研究对象,探讨电磁脉冲(场强为6× 104 V/m)辐照后早期海马区细胞凋亡和病理形态学的变化.在照射后1h、6h、12h、24h和48h分别采用MTT法和流式细胞仪测定死亡细胞和凋亡细胞的比例,用光镜和电镜分别进行形态学观察.结果显示在电磁脉冲辐照后,海马神经细胞不仅发生快速的坏死,而且还发生凋亡,同时在早期即可见到血管、胶质细胞和神经元等组织的形态学异常.表明大鼠大脑受电磁脉冲辐照后早期海马区可发生神经细胞坏死和凋亡,以及各组织成分的病理形态学改变,上述变化可能与电磁脉冲致细胞DNA损伤有关.     

Cell volume regulation in the nervous system

There is good evidence that the three main compartments of the brain, i.e. extracellular space, neurones and glial cells, change their volume during physiological and pathophysiological neuronal activity. However, there is strikingly little knowledge about the mechanisms underlying such alterations in cell volume. For this purpose, a better understanding of the electrophysiological behavior of the neurones and glial cells during volume changes is necessary. Examples are discussed for which changes in cell volume can be derived from the underlying changes in membrane permeabilities. Volume regulatory mechanisms in the brain have not been described under isotonic conditions. However, a rapid volume regulatory decrease is occurring in cultured glial cells during exposure to hypotonic solutions. In contrast, in these cells no volume regulatory increase was found during superfusion with hypertonic media. On the other hand, the entire brain is able to compensate chronic hypertonic perturbations within hours to days. Interestingly, not only ion fluxes induce cellular volume changes but, in turn, water movements can also influence ion fluxes in both neurones and glial cells. With respect to this it should be considered that volume regulatory membrane processes might not exclusively be activated by changes in transmembranal ion gradient, but also by changes of membrane surface shape. Future studies on cellular mechanisms of volume regulation in the brain should imply a combined use of recent techniques such as computerized video-imaging, radiotracer flux measurements and ion-sensitive microelectrodes in defined cell cultures. Optical monitoring and ion-sensitive microelectrodes should enable measurements of volume changes in identified cellular elements of intact nervous structures such as brain slices.     

Nuclear and cytoplasmic RNA in visual cortex neurons of adult rats following visual deprivation and photic stimulation

It has been shown by two-wavelength cytospectrophotometry of gallocyanin-chrome alum-stained sections that visual deprivation in adult rats kept in a complete darkness for 30 days resulted in an accumulation of cytoplasmic RNA by layer V neurons of the visual cerebral cortex and by the cells of the perineuronal neuroglia of this layer. The nuclear RNA content remained unchanged. Stimulation of intact rats with a flickering or constant light induced an increase in the cytoplasmic RNA in these neurons rather than in the nuclear RNA as well as in RNA in their glial satellite cells. Similar light stimulation of the deprived animals gave rise to a complete return of the neuronal RNA to normal with only a slight decrease in the deprivation-induced RNA accumulation by the neuroglial cells. Neither visual deprivation nor light stimulation affected the RNA content in the neurons and neuroglia of layer V of the motor cerebral cortex. Compartmentation of RNA metabolism within the neuronal-neuroglial unit is discussed.     

Role of taurine in osmoregulation in brain cells: Mechanisms and functional implications

Summary All cells including neurons and glial cells are able to keep their volume within a very limited range. The volume regulatory mechanism involves changes in the concentration of osmolytes of which taurine appears to be of particular importance in brain cells. Swelling in brain cells may occur as a result of depolarization or small fluctuations in osmolarity. In isolated brain cells these conditions will always lead to a release of taurine, the time course of which is superimposable on that of the volume regulatory decrease which follows the initial cell swelling. The mechanism responsible for taurine release associated with swelling has not been fully elucidated but a large body of evidence seems to exclude participation of the taurme high affinity carrier. Using a number of inhibitors of anion exchangers it has been demonstrated that both volume regulation and taurine release in brain cells are inhibited by these drugs, implicating an anion channel in the process. It has be controversial issue as to whether or not taurine release is Ca++ dependent. Recent evidence appears to suggest that the release process is not associated with Ca⁺⁺ or Ca⁺⁺ channels. It is, however, quite possible that the swelling process may involve the Ca⁺⁺ calmodulin system or other second messengers. Taurine also contributes to volume regulation after shrinkage of brain cells, in this case by increasing its intracellular concentration. This change is accomplished byan upregulation of the Na+/taurine cotransporter, together with reduced passive fluxes and increased endogenous synthesis.     

Glia associated with central complex lineages in the embryonic brain of the grasshopper Schistocerca gregaria

We have investigated the pattern of glia associated with central complex lineages in the embryonic brain of the grasshopper Schistocerca gregaria. Using the glia-specific marker Repo, we identified glia associated externally with such lineages, termed lineage-extrinsic glia, and glia located internally within the lineages, termed lineage-intrinsic glia. Populations of both glial types increase up to 60 % of embryogenesis, and thereafter decrease. Extrinsic glia change their locations over time, while intrinsic ones are consistently found in the more apical part of a lineage. Apoptosis is not observed for either glial type, suggesting migration is a likely mechanism accounting for changes in glial number. Proliferative glia are present both within and without individual lineages and two glial clusters associated with the lineages, one apically and the other basally, may represent sources of glia.     

Morphometric characteristics of neuron-glial relations in brain edema caused by stimulation of hypothalamic nuclei

Morphologic characteristics and certain changes in cell composition of the cortex and the white substance of the brain have been studied at experimentally produced brain edema by stimulation of the lateral hypothalamic field, the indefinite zone, Forel's fields H1 and H2. It has been stated that diffuse edema of the white substance and perivascular edema dominate in histopathological changes. Morphometrical analysis of the structural changes had demonstrated a certain increase in the cortex thickness, decreased density in the arrangement of the neurons and increased volume of their nuclei at more moderate enlargement of their body volumes, as well as increased volume of the nuclei in the cortical glial cells and the white substance cells. In the cortex cells is observed, that is accompanied with increased glial index and average number of perineuronal gliocytes per one neuron. Simultaneously, in both hemispheres, the character in the arrangement of the perineuronal glia as regards the neuron changes. At the same time, in the white substance, the density of the glial arrangement sharply decreases. The changes have demonstrated that wider perivascular spaces predominate in small vessels. All the changes mentioned are more pronounced in the contralateral hemisphere.     

Analysis of Cyclic AMP-Dependent Changes in Intermediate Filament Protein Phosphorylation and Cell Morphology in Cultured Astroglia

Receptor agonists that increase cyclic AMP levels in cultured astroglia have been shown to increase 32P-labeling of the intermediate filament proteins glial fibrillary acidic protein (GFAP) and vimentin in these cells. Experiments were designed to determine if the increase in 32P-labeling resulted from either an increase in the turnover or net number of phosphates associated with the intermediate filament proteins and if the phosphorylation of these proteins causally affected astroglial morphology. Time course experiments indicated that 6-8 h were required to reach steady-state 32P-labeling of both GFAP and vimentin. Treatment with forskolin (10 microM) after steady-state 32P-labeling increased GFAP and vimentin phosphorylation fourfold and twofold, respectively, and also induced a morphological change from polygonal to process-bearing cells within 20-30 min of drug addition. Cells incubated in media containing brain extract (30%) for 24 h at 37 degrees C and then 3 h at 23 degrees C underwent changes from polygonal to process-bearing cells with no apparent increase in the phosphorylation of either GFAP or vimentin. Treatment of process-bearing cells (induced by brain extract) or polygonal cells with 10 microM forskolin at 23 degrees C resulted in a three- to fourfold increase in GFAP phosphorylation without significant morphological changes. These results suggest that forskolin stimulation of GFAP and vimentin increases net number of phosphates associated with these intermediate filament proteins and that the resulting increase in phosphorylation can be dissociated from morphological changes.     

Neuroglia at the crossroads of homoeostasis,metabolism and signalling: evolution of the concept

Ever since Rudolf Virchow in 1858 publicly announced his apprehension of neuroglia being a true connective substance, this concept has been evolving to encompass a heterogeneous population of cells with various forms and functions. We briefly compare the 19th–20th century perspectives on neuroglia with the up-to-date view of these cells as an integral, and possibly integrating, component of brain metabolism and signalling in heath and disease. We conclude that the unifying property of otherwise diverse functions of various neuroglial cell sub-types is to maintain brain homoeostasis at different levels, from whole organ to molecular.     

Administration of the Glial Condition Medium in the Nucleus Accumbens Prolong Maintenance and Intensify Reinstatement of Morphine-Seeking Behavior

Accumulating evidence suggested that glial cells are involved in synaptic plasticity and behavioral changes induced by drugs abuse. The role of these cells in maintenance and reinstatement of morphine (MRP) conditioned place preference (CPP) remains poorly characterized. The aim of present study was to investigate the direct role of glial cells in nucleus accumbens (NAc) in the maintenance and reinstatement of MRP-seeking behavior. CPP induced with injection of MRP (5 mg/kg, s.c. for 3 days), lasted for 7 days after cessation of MRP treatment and priming dose of MRP (1 mg/kg, s.c.) reinstated the extinguished MRP-induced CPP. The astrocyte-conditioned medium (ACM) and neuroglia conditioned medium (NCM) exposed to MRP (10 and 100 µM) have been microinjected into the NAc. Intra-NAc administration of ACM during extinction period failed to change the maintenance of MRP-CPP, but MRP 100-treated ACM could slightly increase the magnitude of reinstatement. In contrast to ACM, intra-NAc administration of MRP 100-treated NCM caused slower extinction by 3 days and significantly increased the magnitude of reinstatement. Our findings suggest the involvement of glial cells activation in the maintenance and reinstatement of MRP-seeking behaviors, and provides new evidence that these cells might be a potential target for the treatment of MRP addiction.

     

Protein concentration in the neuron--neuroglia system of the anterior horns of the spinal cord in rats following exposure to the tranquilizer diazepam against a background of anticipation stress

Anticipation stress was induced in 16 day-old male rats by placing the animals daily for 7 days into individual cells for 45 min. In the end of each 45 min session, an electric stimulation of paws of the animals was done for 2 min. It was shown by visible cytospectrophotometry of amido black-stained spinal cord sections that the anticipation stress for 7 days resulted in an accumulation of the nuclear and cytoplasmic total proteins in the motoneurons of spinal cord anterior horns, with no changes in the body (in fact, in the nuclei) of the glial cells adjacent to the neurons. Intraperitoneal injection of the tranquilizer diazepam (10 mg per kg) 40 min. before the beginning of the last anticipation stress session gave rise to the return to the normal of the protein content per cell in the motoneuron nucleus and cytoplasm while inducing an increase in the quantity of neuroglia cell protein. Differences in the protein metabolism between the neurons and the neuroglia are discussed.