bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulation of aspects of ischemia in cell culture: Changes in lactate compartmentation
Authors: Walz Wolfgang , Mukerji Srimathie 
Published: January 2005

AbstractAspects of hyperglycemic ischemia were simulated in cultures of astrocytes and of neurons by high glucose and dinitrophenol exposure. Lactate release increased almost sevenfold and it was found that astrocytes were responsible for 92% of the release. There was no significant increase in internal lactate content. Experiments involving loading of astrocytes with lactate at different external pH values showed that lactate accumulation was increased by an increased inward proton gradient. This inward transport of lactate probably consists of two transport components, a passive diffusion of its neutral form and transport via a recently described monocarboxylic acid carrier. It was found that lactate did not get trapped in astrocytes, despite the fact that loading of astrocytes with lactic acid by exposure to 30 mM lactic acid increased the membrane input resistance dramatically. We conclude that lactate is released as lactic acid from astrocytes and equilibrates quickly with all CNS compartments. Thus we argue against a role of lactate accumulation in cytotoxic swelling.
Astrocytes: A possible primary site for colchicine‐mediated neurotoxicity in the rat striatum
Authors: Pitts Olin M. , Cohen Martin R. , McAmis William , Gutman Robert L. 
Published: January 2005

AbstractUltrastructural changes in rat astrocytes including endfoot swelling and rupture of plasma membranes were seen as early as 1 h after injection of 6.0 μg colchicine (CO) into the striatum. Significant change in neuronal morphology was not seen by 24 h. Astrocytes may therefore be primary targets for CO‐mediated damage, which then may have secondary neurotoxic consequences.
Ontogeny of radial and other astroglial cells in murine cerebral cortex
Authors: Misson Jean‐Paul , Takahashi Takao , Caviness Verne S. 
Published: January 2005

AbstractThree cell forms of astroglial lineage populate the prenatal and early postnatal murine cerebral wall. In the present review we consider the ontogeny of these cell forms with respect to histogenetic events of the perinatal period.Classic bipolar radial glial cells predominate prior to E17. The bipolar coexist with monopolar radial forms in the perinatal period. Both bipolar and monopolar radial forms coexist with multipolar astrocytes in the course of the first postnatal week and are ultimately succeeded by the multipolar cells. The shift from bipolar to monopolar radial forms is initially coincident with translocation of somata of bipolar cells from the ventricular zone to the upper intermediate zone and cortical strata. Arborization appears to occur both at the growing tips and along the shaft of the processes of both bipolar and monopolar radial cell types. As arborization continues, the processes of the monopolar radial cells come to resemble those of the multipolar astrocytes. Eventually the radial cells are fully transformed into the multipolar astrocytic forms. During this period of transition, radial processes in the cortex appear to be degenerating, suggesting that regressive processes contribute to the cytologic transformation.This sequence of transformations begins late in the period of neuronal migration and continues through the early stages of growth and differentiation in the murine cerebral cortex. The signals that induce these changes may arise from differentiating neurons within the cortex. These transformations occur at a time when radial glial fibers are no longer required as guides for neuronal migration, and the glial population assumes new roles related to the development and operation of cortical neuronal circuits.
Muscle‐derived factors induce proliferation and astrocytic phenotypic expression in C‐6 glial cells
Authors: Brodie Chaya , Vernadakis Antonia 
Published: January 2005

AbstractPrevious studies from our laboratory have shown that C‐6 glial cells in culture express astrocytic phentoypes with increasing cell passage. Early passage glial cells have been shown to respond to various factors by expressing either astrocytic or oligodendrocytic phenotype. In view of the numerous reports on the trophic effects of muscle‐derived factors on spinal cord neurons, we examined the effect of muscle‐dervied factors on C‐6 glial cells from both early and late passages. Soluble factors were obtained from either leg (LME) or breast (BME) muscle from 15‐day‐old chick embryos by homogenization followed by high velocity centrifugation. Both LME‐ and BME‐derived factors triggered the proliferation and differentiation of early passage glial cells as assessed by cell number and glutamine synthetase activity, respectively. Late passage glial cells responded to muscle‐derved factors with enhanced proliferation and only with a slight increase in glutamine synthetase activity. These findings indicate that glial cells of both early and late passages respond to signals produced by muscle cells.
Gomori‐positive astrocytes: Biological properties and implications for neurologic and neuroendocrine disorders
Authors: Schipper Hyman M. 
Published: January 2005

AbstractGranule laden astrocytes exhibiting an affinity for chrome alum hematoxylin and aldehyde fuchsin (Gomori stains) have been described in the periventricular brain of all terrestrial vertebrate species examined to date including humans. The astrocytic inclusions are rich in sulfhydryl groups, emit an orange‐red autofluorescence, and stain intensely with diaminobenzidine, a marker of endogenous peroxidase activity. The distinct autofluorescence pattern and the absence of neutral lipid, acid phosphatase, and β‐glucuronidase activity exclude lipofuscin or lysosomes as components of these astrocytic granules. The emission of orange‐red autofluorescence and the nonenzymatic nature of the peroxidase activity implicate the presence of porphyrins and metalloporphyrins such as heme as major constituents of these cytoplasmic gliosomes. The role of Gomori‐positive astrocytes under normal and pathologic conditions is incompletely understood. In vivo, numbers of astrocytic granules increase as a function of advancing age, in response to chronic estrogen stimulation, and following X‐irradiation. In vitro, these cells accumulate with increasing time in culture and following exposure to the sulfhydryl agent, cysteamine. Gomori‐positive astrocytes may supply heme to neurons for the synthesis of cytochromes, catalases, and other heme enzymes. They may play a role in photostimulation of sexual cyclicity, the promotion of neuritic development, the degradation of toxic lipoperoxides, and the metabolism of various neurotransmitters. Conversely, these cells may contribute to the pathogenesis of several neurologic and neuroendocrine disorders. Examples of the latter include (a) augmentation of goldthioglucose neurotoxicity, (b) induction of hypothalamic anovulation and reproductive failure, (c) exacerbation of porphyric encephalopathy, and (d) potentiation of parkinsonism and other free radical‐related neurodegenerations.
Glial fibrillary acidic protein in the fish optic nerve
Authors: Blaugrund Eran , Cohen Ilana , Shani Yael , Schwartz Michal 
Published: January 2005

AbstractThe intermediate filament glial fibrillary acidic protein (GFAP) is the predominant cytoskeletal protein of mature glial cells in the mammalian nervous system. The nervous systems of lower vertebrates, such as fish, have been examined for the presence of GFAP and several investigators have shown that goldfish (Carassius auratus) brain contains GFAP‐positive astrocytes. The same studies have demonstrated that, in contrast to the brain, the optic nerve of goldfish did not show any GFAP immunoreactivity, suggesting that this intermediate filament protein is not expressed in fish optic nerve astrocytes. The present study shows, however, that the monoclonal antibodies to porcine GFAP react with the optic nerve of carp (Cyprinus carpio), another member of the goldfish family. These antibodies to porcine GFAP cross react with rat brain and carp optic nerve, yielding a band of approximately 52 kDa in both species. Northern blot analysis using mouse GFAP DNA probe revealed that carp optic nerve RNA contains two transcripts, of 2.3 and 2.1 kb, which hybridize with the mouse GFAP probe. Injury to the carp optic nerve was followed by a decrease of GFAP immunoreactivity from neural tissue and a strong expression around blood vessels and connective tissues. On the basis of these observations and within the limitation of the techniques it is reasonable to conclude that the carp optic nerve expresses GFAP immunoreactivity and that the pattern of expression of this intermediate filament protein is altered after injury. Such an alteration might be relevant to the process of regeneration.
Axon‐glia interactions in the crayfish: Glial cell oxygen consumption is tightly coupled to axon metabolism
Authors: Hargittai Pa'l T. , Lieberman Edward M. 
Published: January 2005

AbstractOxygen consumption (Q̇) of single isolated axons and their associated glial cell sheath was investigated under a variety of conditions to determine the contribution of each cell type to whole tissue Q̇. It was found that the Q̇ of the sheath, in the absence of a functional axon, represented approximately 30% of the total tissue Q̇. When the axon was injected with carboxyatractyloside, an inhibitor of mitochondrial oxidative phosphorylation that is membrane impermeant, electrophysiological properties of the axon were not affected and glial sheath respiratory activity was stimulated by 1.7 to 2.7 times the untreated control level.These results suggest that glial cell metabolic activity is regulated by the metabolic activity of the axon. Depending on the experimental conditions the glial sheath accounts for 30% to nearly 100% of the Q̇ of axon‐glial cell tissue. On the basis of these and morphometric measurements we estimated that in a normally functioning axon‐glial cell system the glial sheath accounts for 90% of the tissue Q̇.
Cerebral type 2 astroglia are heterogeneous with respect to their ability to respond to neuroligands linked to calcium mobilization
Authors: Dave Vijendra , Gordon Gerald W. , McCarthy Ken D. 
Published: January 2005

AbstractVery little information is available concerning the pharmacology of type 2 astroglia. During the past decade it has become apparent that two distinct lineages of astroglial cells can be defined in vitro. These two lineages are commonly referred to as type 1 and type 2 and are distinguished from each other on the basis of their morphological features and antigenic phenotypes. In contrast to type 1 astroglia, very little is known about the pharmacology of type 2 astroglia. The lack of information concerning the responsiveness of these cells stems primarily from difficulties encountered in isolating large numbers of type 2 astroglia free of other cell types. In the present study video‐ and photometer‐based imaging systems were used to monitor the influence of a series of neuroligands on the intracellular calcium levels of individual cerebral type 2 astroglia in order to assess their expression of calcium‐mobilizing receptors. The responses of 85 immunocytochemically identified cerebral type 2 astroglia to bradykinin (BK), norepinephrine (NE), histamine (HIST), carbachol (CARB), 2‐methyl‐thio ATP (2MT‐ATP), glutamate (GLUT), and serotonin (5‐HT) were analyzed. Approximately 50% of cerebral type 2 astroglia responded to BK, NE, HIST, CARB, and 2MT‐ATP whereas only 16% and 9% of the cells responded to GLUT and 5‐HT, respectively. The number of neuroligands that increased calcium in individual cells ranged from 0 to 6. These responses are quite similar to those previously demonstrated in cultured cerebral type 1 astroglia. No pattern of receptor co‐expression was observed for the different neuroligands tested. While variable, distinct differences were observed in the time course of the calcium responses elicited by different neuroligands. The present study demonstrates that cultured cerebral type 2 astroglia are heterogenous when judged by their ability to respond to neuroligands with a rise in intracellular calcium.
Response of müller cells to growth factors alters with time in culture
Authors: Small R. K. , Patel P. , Watkins B. A. 
Published: January 2005

AbstractWe have developed an explant culture technique, using the retinae of newborn guinea pigs, that reliably yields cultures of Müller cells showing uniform morphology and phenotype. Since the guinea pig retina is avascular and lacks astrocytes, Müller cells are the only glial cell‐type and the only vimentin‐positive population present. Virtually all passaged cells (<98%) contain vimentin‐positive intermediate filaments and no glial fibrillary acidic protein (GFAP) has been detected using a range of GFAP antibodies known to label astrocytes in the guinea pig optic nerve. Most vimentin‐positive cells were also labeled with an antibody to carbonic anhydrase II, an enzyme which in the retina is specific for Müller cells. Proliferating Müller cells were identified within the inner nuclear layer of retinal fragments as early as 2 days in culture using bromodeoxyuridine (BrdU) and vimentin double labeling. Cultured Müller cells change their growth characteristics with successive passaging. The length of the cell cycle increases from 25.4 h for cells at first passage, to 66.7 h for cells at fourth passage. Altered responses to mitogens were also observed with passaging. First‐passage cultures responded to basic fibroblast growth factor (bFGF) but not to several other factors tested including interleukin‐2 (IL‐2). In contrast, older cultures were highly responsive to IL‐2 but showed a minimal response to bFGF. The altered responsiveness to mitogens observed in vitro may be relevant to changes in growth control of Müller cells in the developing and mature retina.The guinea pig retina provides an ideal mammalian tissue for generating Müller cell cultures that are free of astrocytes, endothelial cells, and pericytes, the most frequent contaminants of retinal glial cultures. The monolayers obtained show a high degree of homogeneity and are well suited for studies of Müller cell function.
Evidence for glial control of extracellular pH in the leech central nervous system
Authors: Deitmer Joachim W. 
Published: January 2005

AbstractDouble‐barrelled pH‐sensitive microelectrodes were used to measure the intracellular pH (pHi) of neuropil glial cells and the pH of extracellular spaces (pHe) within isolated, intact ganglia of the leech Hirude medicinalis. By application of a weak acid (propionate, 40 mM) or a weak base (ammonium, 20 mM) the total buffer capacity was estimated by changes in glial pHi and in pHe. The buffering power of glial cells and in the extracellular spaces was increased by up to threefold in the presence of CO2/bicarbonate. The anion exchange inhibitor 4,4‐diisothiocyanatostillbene‐2,2′‐disulphonic acid (DIDS, 0.3–0.5 mM) reversed this increase in buffering power both in the glial cells and in the extracellular spaces. Inhibitors of the carbonic anhydrases reduced the CO2/bicarbonate‐dependent increase in extracellular buffering power. The results suggest that extracellular H+ buffering dependent upon the availability of bicarbonate is linked to DIDS‐sensitive bicarbonate transport across the glial membrane.
The olfactory nerve contains two populations of glia, identified both in vivo and in vitro
Authors: Pixley Sarah K. 
Published: January 2005

AbstractThe peripheral olfactory nervous sysstem exhibits, uniquely, neuronal cell body replacement and reestablishment of central connections in adult mammals. The role of the olfactory nerve glia in these phenomena is unknown, but information might be provided by in vitro systems. This paper reports on the characterization of olfactory nerve glia in dissociated cell cultures of newborn rat nasal mucosal tissues. The predominant type of glial cell resembled Schwann cells and immunostained for the S‐100 protein, found in all glial cell types; glial fibrillary acidic protein (GFAP), found in astrocytes and nonmyelinating Schwann cells; and showed binding of 217C, a monoclonal Schwann‐cell marker that binds to the low‐affinity NGF receptor in glioma cells. They were negative for A2B5. The Schwann‐cell‐like olfactory glia changed morphology upon culturing in serum‐free medium, with further shape changes after plating on laminin. Plating on laminin increased cell numbers. A second population, found only after GFAP‐immunostaining, was astrocyte‐like in morphology and represented approximately 10 percent of all glial cells. These were S‐100‐, A2B5‐, and 217C‐negative, a unique glial cell immunological profile. At low dilutions of anti‐GFAP (1/10,000), or with weak fluorescent second ary antibodies, astrocyte‐like glia were immunostained but Schwann‐cell‐like glia were not detectable. Astrocyte‐like glia were not an artifact of the dissection, since they were detectable in tissue sections of newborn‐rat olfactory nerves immunostained with a low dilution of anti‐GFAP. The presence of two types of glial cell in culture suggests similarities between olfactory glia and entric glia. © 1992 Wiley‐Liss, Inc.
Type‐1 and type‐2 astrocytes are distinct targets for prostaglandins D2, E2, and F2α
Authors: Ito Seiji , Sugama Kazushige , Inagaki Naoyuki , Fukui Hiroyuki , Giles Heather , Wada Hiroshi , Hayaishi Osamu 
Published: January 2005

AbstractAccumulating evidence has revealed that astrocytes are potential targets for various neurotransmitters. Here we investigated the effects of prostaglandins (PGs) on signal transduction in purified primary cultures of rat type‐1 and type‐2 astrocytes. PGF2α, PGD2, and 9α, 11β‐PGF2, a metabolite of PGD2 and a stereoisomer of PGF2α, evoked a rapid rise in the intracellular Ca2 concentration ([Ca2+]i) in type‐1, but not in type‐2, astrocytes. STA2, a stable analogue of thromboxane A2, was less effective, and PGE2 showed little effect. The PG‐induced rise in [Ca2+]i was not blocked by an antagonist of either PGD2 receptor or thromboxane A2 receptor. PGF2α and 9α, 11β‐PGF2 stimulated rapid formation of inositol trisphosphate followed by inositol bisphosphate and inositol monophosphate. On the other hand, PGE2 increased the intracellular level of cyclic AMP in type‐2 astrocytes, rather than in type‐1 astrocytes. The potency of PGs for cyclic AMP formation was in the following order: PGE2 > PGE1 ≥ STA2 > iloprost, a stable analogue of PGI2. PGD2 and PGF2α had no effect on cyclic AMP formation. These results demonstrate that type‐1 astrocytes preferentially express PGF2α receptors, the activation of which leads to phosphoinositide metabolism and [Ca2+]i elevation, whereas type‐2 astrocytes possess PGE receptors that are linked to cyclic AMP formation. © 1992 Wiley‐Liss, Inc.
Different response of astrocytes and bergmann glial cells to portacaval shunt: An immunohistochemical study in the rat cerebellum
Authors: Suárez I. , Bodega G. , Arilla E. , Rubio M. , Villalba R. , Fernández B. 
Published: January 2005

AbstractThe present study was performed in order to follow the response of rat cerebellum astroglial cells (Bergmann glial cells and astrocytes) to long‐term portacaval shunt (PCS), by means of glial fibrillary acidic protein (GFAP) and vimentin immunoreactivities. Bergmann glia accumulated GFAP in response to PCS, whereas astrocytes decreased GFAP immunoreactivity when compared to control rats. The increase of GFAP occurs in cells located in the cerebellar layer where glutamate is mainly released. Since the vimentin content remained unaltered in response to PCS, when compared to control rats, it can be concluded that only the GFAP filaments are affected by PCS. Nevertheless, GFAP immunoreactivity presents regional differences in the cerebellar astroglial population, and the factors responsible for these variations are still unknown. © 1992 Wiley‐Liss, Inc.
Characterization of specific binding sites for [3H]‐1,3‐di‐o‐tolyl‐guanidine (DTG) in the rat glioma cell line C6‐BU‐1
Authors: Georg Andrea , Friedl Arno 
Published: January 2005

AbstractThe aim of the present study was to find out if a cell line of glial origin possesses sigma and/or phencyclidine (PCP) binding sites. Binding of [3H]1,3‐di‐o‐tolyl‐guanidine (DTG), a highly selective ligand for sigma binding sites, and of [3H]N‐[1‐(2‐thienyl)cyclohexyl] piperidine ([3H]TCP), a radioligand specific for PCP receptors, to C6‐BU‐1 glioma cells was investigated. Binding of [3H]DTG to C6‐BU‐1 cell membranes was reversible, saturable (Bmax = 10.5 pmol/mg protein), and of high affinity (KD = 26 nM). C6‐BU‐1 cells do not possess PCP receptors as indicated by negligible specific binding of [3H]TCP to C6‐BU‐1 cell membranes. Specific binding of [3H]DTG was reduced in the presence of Ca2+ and to a lesser extent by Mg2+ and to a lesser extent by Mg2+. The rank order of potency of various PCP and sigma ligands was DTG > (+)3‐[(3‐hydroxy‐phenyl)‐N‐n‐propyl‐piperidine] [(+)3‐PPP] > haloperidol > pentazocine > (‐)3‐PPP > PCP > metaphit > dextromethorphan > (‐)butaclamol > (+)butaclamol > (‐)N‐allylnormetazocine [(‐)SKF 10,047] > MK801 > (+)SKF 10,047 > ketamine. The drug specificity, confirmed by a reversed stereoselectivity for the benzomorphan opiate SKF 10,047, indicated that these sites correspond to a subtype of sigma binding sites, the so‐called sigma 2 binding site. Thus, the C6‐BU‐1 cell line is the first glial cell line demonstrated to have sigma 2 binding sites. © 1992 Wiley‐Liss, Inc.
Microglia progenitor cells: A subpopulation in cultures of mouse neopallial astroglia
Authors: Richardson A. , Hao C. , Fedoroff S. 
Published: January 2005

AbstractWe have shown that astroglia cultures initiated from newborn mouse neopallium contain microglia progenitor cells. Astroglia secrete growth factor(s) that transform the progenitor cells into microglia. One of the trophic factors is bone marrow macrophage growth factor CSF‐1. Mouse embryonic fibroblast cells STO also secrete trophic factor(s) that acts synergistically or additively with CSF‐1 on microglia progenitor cells. Using limiting dilution analysis we estimated that in the presence of CSF‐1 and STO cells, 1 in every 8 cells in astroglia cultures is a potential microglia progenitor cell.
Effects of transforming growth factor‐β1 on the extracellular matrix and cytoskeleton of cultured astrocytes
Authors: Baghdassarian Denise , Toru‐Delbauffe Daniele , Gavaret Jean Michel , Pierre Michel 
Published: January 2005

AbstractThe present study was performed on primary cultures and subcultures of cerebellar astrocytes in order to investigate the effects of transforming growth factor‐β1 (TGFβ1) on proliferation, extracellular matrix (ECM) components, and cytoskeletal structures in relation to morphological changes. The expression and cellular distribution of the ECM components laminin and fibronectin and the cytoskeletal proteins glial fibrillary acidic protein (GFAP) and actin were investigated by immunoblotting, immunocytochemistry, and phalloidin staining. The proliferation of primary cultures was strongly inhibited by TGFβ1. Treated cells became enlarged and spread onto the substratum. TGFβ1 promoted the appearance of actin stress fibers and increased the cell actin content. It elicited a slight increase in GFAP expression and induced dispersion of thin filaments of GFAP. TGFβ1 also stimulated the production of laminin and fibronectin and their incorporation into the ECM of primary cultures grown in medium with or without serum Astrocytes grown in serum‐containing medium for 1 day after subculturing responded strongly to TGFβ1.Changes promoted by TGFβ1 in cell shape, cytoskeleton, and ECM production of cultured astrocytes may have relevance for understanding the mechanisms of action of TGFβ1 during brain development.