bluuebunny/crossref_metadata_2025 huggingface dataset:
Response of müller cells to growth factors alters with time in culture
Authors: Small R. K. , Patel P. , Watkins B. A.
Published: January 2005

We 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

Double‐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

The 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

Accumulating 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

The 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

The 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

We 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

The 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.
Transforming growth factor‐βs inhibit mitogen‐stimulated proliferation of astrocytes
Authors: Hunter Kim E. , Sporn Michael B. , Davies Alun M.
Published: January 2005

We have studied the influence of three members of the transforming growth factor‐β (TGF‐β) family of multifunctional growth factors on the proliferation of cultured astrocytes isolated from newborn mouse cerebral cortex. Although TGF‐βs 1, 2, and 3 cause only a small reduction in the low level of astrocyte proliferation occurring in chemically defined medium, they each inhibit the effects of five astrocyte mitogens (bFGF, EGF, PDGF, IL‐1α, and IL‐2). Inhibition is observed when astrocytes are exposed to mitogen and TGF‐r3 at the same time and when they are exposed to TGF‐β prior to, and separately from, mitogen. This latter effect appears to be due to the binding of TGF‐βs to astrocyte‐secreted extracellular matrix. These findings raise the possibility that TGF‐β may co‐operate with other growth factors to control astrocyte proliferation in vivo.
Distinct effects of bFGF and PDGF on oligodendrocyte progenitor cells
Authors: McKinnon Randall D. , Smith Carolyn , Behar Toby , Smith Thomas , Dubois‐Dalcq Monique
Published: January 2005

We have compared the effects of platelet‐derived (PDGF) and basic fibroblast (bFGF) growth factors on the shape, migration, and differentiation of oligodendrocyte progenitor cells, the precursors of myelin‐forming cells in the CNS. In the presence of bFGF, oligodendrocyte progenitors purified from rat neonatal brain cultures were stellate, non‐motile, and had a morphological complexity of 1.26 ± 0.03 as measured by fractal dimension (D). These cells expressed transcripts encoding the POU‐homeodomain transcription factor Oct‐6, but not myelin genes. Upon addition of PDGF, bFGF‐treated cells became motile and twofold less complex in shape (D = 1.19 ± 0.03). These changes occurred within 6 ± 4 h and were dependent on de novo transcription and translation, but not DNA synthesis. Upon removal of PDGF the cells reverted to their stellate shape (D = 1.26). Removal of both bFGF and PDGF resulted in oligodendrocyte differentiation after 3 days, with a fourfold increase in complexity of shape (D = 1.55 ± 0.08), loss of Oct‐6 transcripts, and gain of myelin transcripts. Thus PDGF is both necessary and sufficient to induce a motile state in progenitor cells growing in the presence of bFGF. Together with our previous data (McKinnon et al.: Neuron 5:603, 1990), our results suggest that bFGF and PDGF may control distinct phases of proliferation and migration of oligodendrocyte progenitor cells in vivo.
Spinal cord astrocytes in vitro: Phenotypic diversity and sodium channel immunoreactivity
Authors: Black J. A. , Sontheimer H. , Waxman S. G.
Published: January 2005

The expression of sodium channels in morphologically and antigenically distinct astrocytes derived from neonatal rat spinal cords was examined at various times in culture. During the course of this study [2‐40 days in vitro (DIV)], nine morphologies of glial fibrillary acidic protein (GFAP)+ cells were distinguished: (1a) flat, fibroblast‐like; (1b) elongated, with generally few, short processes; (1c) triangular soma with three short, stubby processes; (1d) bipolar with long, slender processes; (1e) bipolar with broad, flared processes; (1f) stellate with radially oriented slender processes extending from a small to moderate‐sized soma; (1g) multiple short, stubby processes extending from a moderate‐sized soma; (1h) flat, roundish shape with either a smooth edge (“pancake”‐like) or numerous very short processes; and (1i) broad, elongated cell body with orthogonally oriented short, spike‐like processes. Not all cell types were present at all times in culture. Each type of astrocyte displayed sodium channel immunoreactivity at some time in culture; however, different types of astrocytes exhibited different patterns, over time, of sodium channel staining. Sodium channel immunoreactivity in all astrocyte types was reduced to low levels by 14 DIV, and was not detectable at 40 DIV. Except for types 1b and 1e, A2B5 staining was present on all astrocyte morphologies at some time in culture, and was generally attenuated with longer times in vitro; in contrast to cultures derived from neonatal rat optic nerve, A2B5 staining does not distinguish unequivocally between the various classes of morphologically different astrocytes derived from spinal cord. O4 immunoreactivity was consistently observed only on bipolar, elongated, and process‐bearing astrocytes, though not all process‐bearing astrocytes were O4+. These results demonstrate that astrocytes derived from neonatal spinal cord are morphologically and antigenically heterogeneous. Moreover, while spinal cord astrocytes express sodium channels, these astrocytes exhibit a time‐course of channel expression that is different from astrocytes derived from several other CNS regions where sodium channel staining is maintained even for extended times in culture, suggesting a regional modulation of astrocyte function.
Independent changes of intracellular calcium and pH in identified leech glial cells
Authors: Deitmer Joachim W. , Schneider Hans‐Peter , Munsch Thomas
Published: January 2005

The intracellular Ca2+ (Ca2+i) and the intracellular pH (pHi) were measured in identified neuropile glial cells in the central nervous system of the leech Hirudo medicinalis, using the fluorescent dye fura‐2, and double‐barrelled, neutral carrier, pH‐sensitive microelectrodes. Different stimuli were used to elicit Ca2+i and/or pHi changes, such as application of ammonium, high external K+‐concentration, and low external pH. Ammonium (20 mM) and high external K+ (20 mM), which depolarized the glial membrane by 20–30 mV, evoked rapid and large rises of Ca2+i. In contrast to the Ca2i changes, amplitude and direction of the pHi changes were dependent on the presence of CO2/HCO3− in the saline. The addition of CO2/HCO3−, and the subsequent reduction of external pH from 7.4 to 7.0, had no effect on Ca2+i, but caused significant changes of pHi. The results suggest that the ammonium‐ and K+‐induced Ca2+i rises were due to the membrane depolarization leading to a Ca2+ influx through voltage‐gated Ca2+ channels in the glial membrane, while the pHi changes resulted from movements of ammonia and from the activation or inhibition of the Na+‐HCO3− cotransporter. This indicates that changes of intracellular Ca2+ and pH can occur independently of each other, suggesting that the homeostasis of these ions is not necessarily interrelated in these glial cells.
Oligodendroglial lineage cells express neuroligand receptors
Authors: Kastritsis C. H. , McCarthy Ken D.
Published: January 2005

This study was designed to determine whether cells of the oligodendroglial lineage express neuroligand receptors linked to Ca2+ mobilization. Intracellular Ca2+ levels were monitored with a video‐based imaging system and cells were characterized with immunocytochemical markers. O‐2A progenitor cells (A2B5+/GFAP‐) and mature oligodendroglia (GC+/MBP+) responded to norepinephrine, glutamate, ATP, and histamine with increased intracellular Ca2+ levels. As O‐2A progenitor cells differentiated into mature oligodendroglia, there was an increase in the percentage of cells that responded to ATP and histamine with an increase in intracellular Ca2+ levels. Both O‐2A progenitor cells and mature oligodendroglia were pharmacologically heterogeneous with respect to their ability to respond to neuroligands with an increase in intracellular Ca2+. Treatment with bradykinin, carbachol, and substance P also increased intracellular Ca2+ levels in O‐2A progenitor cells and mature oligodendroglia. Whereas the percentage of cells that responded to bradykinin and substance P increased with differentiation of O‐2A progenitor cells into mature oligodendroglia, the trend was reversed with respect to the percentage of cells responding to carbachol. These results suggest that cells of the oligodendroglial lineage exhibit neuroligand receptors linked to Ca2+ mobilization and that the ability of these cells to respond to neuroligands is developmentally regulated. © 1993 Wiley‐Liss, Inc.
Formation of the myelinated nerve fiber layer in the chicken retina
Authors: Nakazawa Tomoko , Tachi Sumie , Aikawa Eizo , Ihnuma Morio
Published: January 2005

Oligodendrocytes in the ganglion cell layer, the myelinating cells in the chicken retina, were investigated morphologically and quantitatively. Oligodendroblasts divided in the inner retinal layer around the 14th day of incubation and differentiated into oligodendrocytes. The oligodendrocytes started sheathing an axon in the nerve fiber layer at the 14th day of incubation. The number of myelin lamellae increased rapidly during the first week after chicks had hatched. An immunological reaction of antimyelin basic protein was observed on the myelin sheaths in the nerve fiber layer and on the oligodendrocytes in the ganglion cell layer. These results suggest that the oligodendrocytes form the myelinated nerve fiber layer of the chicken and that they act independently of the Müller cells during myelination. © 1993 Wiley‐Liss, Inc.
Monoamine oxidase‐B in astrocytes
Authors: Ekblom Jonas , Jossan Sukhwinder S. , Bergstrüm Mats , Oreland Lars , Walum Erik , Aquilonius Sten‐Magnus
Published: January 2005

In the present report we describe the astrocytic localization and content of monoamine oxidase‐B (MAO‐B) by means of a 3H‐L‐deprenyl emulsion autoradiography in primary cultures of rat astrocytes, in cryosectioned astrocytoma surgical specimen, and in cryosections of human spinal cords from patients dying in amyotrophic lateral sclerosis (ALS) and controls.

The occurrence of MAO‐B enzyme protein depends on the degree of cellular differentiation as demonstrated by studies on astrocytes in primary cultures analyzed at two different stages of maturation. Highly differentiated cells exhibited high relative enzyme concentration whereas glioblasts lacked or showed very low contents of MAO‐B enzyme. This was further substantiated by studies performed on human astrocytoma tissue using 3H‐L‐deprenyl emulsion autoradiography in combination with immunohistochemical detection of glial fibrillary acidic protein (GFAP).

Regional increases of MAO‐B concentration were found in ALS lumbar sections with quantitative 3H‐L‐deprenyl autoradiography. On the basis of results obtained from double staining for GFAP and MAO‐B, the increase in MAO‐B seemed to be due to an increased number of astrocytes as well as an increased content of MAO‐B in reactive species of astrocytes. A cell culture model has been used that produces cells with morphology and GFAP‐content similar to reactive cells. These astrocytes exhibited high relative content of the MAO‐B enzyme protein.

In the light of the presented data, taking into account the finding that a subpopulation of reactive cells contained low levels of MAO‐B, a heterogeneity among reactive astrocytes was observed. © 1993 Wiley‐Liss, Inc.
Coexpression of PMP22 gene with MBP and P0 during de novo myelination and nerve repair
Authors: Kuhn G. , Lie A. , Wilms S. , Müller H. W.
Published: January 2005

The recently cloned PMP22 gene, the rat variant of the murine growth arrest‐specific gene gas3, encodes a new 22 kD integral membrane glycoprotein of peripheral myelin. By means of in situ hybridization and immunohistochemistry, we have (1) analyzed PMP22 expression in myelinated and nonmyelinated peripheral nerves, and (2) compared the spatio‐temporal changes in the expression of PMP22 mRNA with the expression of the myelin genes P0 and MBP (myelin basic protein) in developing as well as degenerating and regenerating sciatic nerve of rat. (3) We further investigated the expression of PMP22 mRNA by Northern blot in cultured Schwann cells maintained under different conditions of cell growth and arrest. Expression of PMP22 mRNA is restricted to Schwann cells of myelinated peripheral nerve. Transection of sciatic nerve in adult rat leads to a simultaneous and rapid decline in both PMP22 and P0 mRNA to nondetectable levels in the degenerating distal stump. When a demyelinated and axon‐free distal stump, as indicated by the lack of MBP and neurofilament immunoreactivity, was reanastomosed to its proximal counterpart, the coordinated reexpression of PMP22 and MBP succeeded axonal regeneration through the distal segment with a delay of 1‐2 weeks. As in regenerating nerve, a striking synchrony of expression of PMP22 and P0 transcripts, as well as MBP immunoreactivity, could be observed during sciatic nerve development. Further, in vitro evidence suggests that, unlike NIH3T3‐fibroblasts, expression of PMP22/gas3 is not strictly growth arrest‐specific in Schwann cells. In conclusion, the spatio‐temporal pattern of PMP22 gene expression in developing, injured, and regenerating peripheral nerve very closely resembles P0 and MBP expression, indicating a mechanism of PMP22 gene regulation in Schwann cells that is similar or identical to that of established myelin genes. © 1993 Wiley‐Liss, Inc.
Expression of janusin (J1–160/180) in the retina and optic nerve of the developing and adult mouse
Authors: Bartsch Udo , Pesheva Penka , Raff Martin , Schachner Melitta
Published: January 2005

We have analyzed the expression of the oligodendrocyte‐derived extracellular matrix molecule janusin (previously termed J1–160/180) in the retina and optic nerve ofdeveloping and adult mice using indirect light and electron microscopic immunocytochemistry, immunoblot analysis, and enzyme‐linked immunosorbent assay. In the optic nerve, janusin is not detectable in neonatal and only weakly detectable in 7‐day‐old animals. Expression is at a peak in 2‐ or 3‐week‐old animals and subsequently decreases with inceasing age. In the retina, expression inceases until the third postnatal week and then remains at a constant level. In immunocytochemical investigations at the light microscopic level, janusin was found in the myelinated regions of the nerve with spots of increased immunoreactivity possibly corresponding to an accumulation of the light microscopic level, janusin was found in the myelinated regions of the nerve with sports of increased immunoreactivity possibly corresponding to an accumulation of the molecule at the nodes of Ranvier. At the electron microscopic level, contact sites between unmyelinated axons, between axons, and glial cells, and between axons and processes of myelinating oligodendrocytes were immunoreactive. Cell surfaces of astrocytes at the periphery of the nerve and forming the glial‐limiting membrane, in contrast, were only weakly immunopositive or negative. In cell cultures of young postnatal mouse or rat optic nerves, oligodendrocytes and type‐2 astrocytes, but not type‐1 astrocytes were stained by janusin antibodies. In the oligodendrocyte‐free retina, janusin was detectable in association with neuronal cell surfaces, but not with cell surfaces of Muller cells or retinal astrocytes. Our observations indicate that expression of janusin in the optic nerve and in the retina is developmentally differentially regulated and that other cell types, in addition to oligodendrocytes, express the molecule. Since the time course of janusin expression in the optic nerve coincides with the appearance of oligodendrocytes and myelin and since janusin is associated with cell surfaces of oligodendrocytes and outer aspects of myelin sheaths and is concentrated at nodes of Ranvier, we suggest that janusin is functionally involved in the process of myelination. © 1993 Wiley‐Liss, Inc.
Microglial response to degeneration of serotonergic axon terminals
Authors: Wilson Mary Ann , Molliver Mark E.
Published: January 2005

The neurotoxic drug p‐chloramphetamine (PCA) causes widespread de‐generation offine, unmyelinated serotonergic (5‐HT) axons in the forebrain. PCA toxicity is selective for 5‐HT axon terminals; preterminal axons and cell bodies are spared. Degeneration is followed by slowly progressive axonal sprouting and partial reinnervation. PCA is injected subcutaneously; this route of administration avoids mechanical disruption of the blood brain barrier. The present study analyzed the response of microglia and astrocytes in rat brain to selective ablation of 5‐HT axons by PCA. Several microglial markers were analyzed with immunocytochemical methods. An increase in the number of microglial processes and in immunoreactive staining was observed with antibodies directed against CR‐3, MHC‐I, CD4, and rat LCA. The microglial response was maximal 3 weeks after PCA treatment, became less evident 6 weeks after treatment, and by 9 weeks no difference was observed between treated and control rats. No change was detected in MHC‐II or the macrophage marker ED1, nor in expression of GFAP by astrocytes. Thus, degeneration of 5‐HT axon terminals affects only a subset of the micro‐glial markers examined; in comparison, retrograde reaction to facial nerve transection causes a robust increase in all of these markers and in GFAP. The microglial response to PCA‐induced axon loss is slow in onset and small in magnitude. These findings indicate that CNS microglia are activated by degeneration of fine, unmyelinated 5‐HT axon terminals; furthermore, sensitive microglial markers can detect a subtle axonal lesion that provokes no detectable increase in GFAP expression by astrocytes. © 1994 Wiley‐Liss, Inc.
FGF‐2 in the MPTP model of parkinson's disease: Effects on astroglial cells
Authors: Otto Dörte , Unsicker Klaus
Published: January 2005

Fibroblast growth factor (FGF) is synthesized and stored by astroglial cells and regulates their proliferation and differentiation in vitro. Its implication in the transformation of quiescent astrocytes into reactive astroglia has been discussed. Using a mouse model of Parkinson's disease, in which FGF‐2 has been shown to exert marked neuroprotection of nigrostriatal dopaminergic neurons, we have studied striatal levels of glial fibrillary acidic protein (GFAP), an established marker for astrocytes, and the distribution and morphologies of GFAP‐immunoreactive cells following treatments with the neurotoxic drug 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP), the growth factor FGF‐2, and the non‐trophic control protein cytochrome C (cyt C). Systemic injections of MPTP (30 mg/kg) on 3 consecutive days, which we have previously shown to cause profound and long‐lasting damage to the nigrostriatal system, induced an approximate 20% transient increase in striatal GFAP, determined by enzyme‐linked immunosorbent assay (ELISA), 1 day after the final MPTP injection (= day 4), with subsequent normalization at day 7, which lasted until the end of the experiment (day 18). Morphologically, MPTP elicited a marked increase in number, size, arborization, and stainability of GFAP‐immunoreactive cells at day 4 in a striatal area adjacent to the corpus callosum, which was evaluated throughout all experiments. Even on day 18, astrocytes were still apparently larger and more branched than in unlesioned controls. Administration of 4 μg of either FGF‐2 or cyt C (soaked into a piece of Gelfoam unilaterally to the right striatum in either MPTP‐ or saline‐injected controls) increased striatal GFAP levels bilaterally about 2‐ to 2.5‐fold at 14 days, when FGF‐2 showed marked protection of dopaminergic parameters. Likewise, GFAP immunocytochemistry revealed increased numbers of intensely immunoreactive astrocytes under any experimental situation. Differences in the morphologies of astrocytes in FGF‐2‐ and cyt C‐treated animals were very subtle and only noted at greater distances away from the site of application of the factors. We conclude that FGF‐2, a potent neurotrophic factor for the neurotoxically lesioned nigrostriatal system, does not cause a marked astrogliotic reaction, which might be expected from previous in vitro and in vivo studies in other neural systems. This may limit concerns regarding potential applicability of FGF‐2 to the parkinsonian striatum. © 1994 Wiley‐Liss, Inc.
Roles for protein kinases in the induction of nitric oxide synthase in astrocytes
Authors: Simmons Martha L. , Murphy Sean
Published: January 2005

Lipopolysaccharide (LPS) or a combination of interferon (IFN)‐γ and interleukin (IL)‐1β can induce a calcium‐independent nitric oxide synthase (iNOS) in astrocyte cultures (Simmons and Murphy: J Neurochem 59:897, 1992; Eur J Neurosci 5:825,1993; Galea et al: Proc Natl Acad Sci USA 89:10945,1992). This induction can be measured by assaying cyclic GMP levels in the cultures, which correlates with, but is more sensitive than, measurement of nitrite accumulation. To study potential second‐messenger systems involved in the induction of iNOS, phorbol 12‐myristate 13‐acetate (PMA), a protein kinase C (PKC) activator, and various protein kinase inhibitors were employed. PMA induced a time‐, dose‐, and L‐arginine‐dependent increase in cyclic GMP, which could be inhabited by dexamethasone or actinomycin D. This induction could be dramatically increased by concurrent treatment with IFN‐y. The presence of iNOS mRNA could be demonstrated by hybridization with a specific cDNA probe. H7 (a non‐specific serine/threonine kinase inhibitor) but not H89 (a more specific PKA inhibitor) prevented induction by all agents. However, downregulation of PKC or pretreatment with the PKC inhibitor calphostin C did not prevent the induction by LPS or cytokines, suggesting that PKC is not necessary for iNOS induction by these mediators. Additionally, genistein (a nonspecific tyrosine kinase inhibitor) could prevent induction by all agents, but the more specific inhibitor, tyrphostin, attenuated only NOS induction by LPS. These results suggest that activation ofPKC can lead to, but is not necessary for, the induction of NOS in astrocytes and that there is a potential role for tyrosine kinases in NOS induction by LPS. This complex control of induction of iNOS, seemingly requiring activation of multiple pathways for maximal effect, might represent a safeguard to prevent production of potentially toxic nitric oxide (NO) under normal physiological conditions. © 1994 Wiley‐Liss, Inc.
Mobilization of intracellular calcium by substance p in a human astrocytoma cell line (U‐373 MG)
Authors: Bordey A. , Feltz P. , Trouslard J.
Published: January 2005

Variations in intracellular free calcium concentration (Δ[Ca2+]i) were measured in intact and isolated human astrocytoma cells (U373 MG) loaded with fura‐2 acetoxymethylester. Microperfusion of 50 nM substance P (SP), applied for 1 s, increased [Ca2+]i by 351 nM from a stable basal level of [Ca2+]i of 26 nM. The peak Δ[Ca2+]i induced by SP was dose dependent with a threshold of 10‐3 nM, an ED50 of 1.3 nM and a maximal effect for concentrations of SP greater than 100 nM. The NKI receptor agonist, [Sar9Met(O2)11]SP, mimicked the effect of SP, while the NK2 and NK3 selective receptor agonists, [N110]NKA(4‐10) and senktide, respectively, had no effect. The Δ[Ca2+]i induced by SP was unaffected by 100 μM cadmium or by removal of extracellular calcium ions. Caffeine up to 30 mM had no effect on [Ca2+]i. In contrast, thapsigargin increased resting [Ca2+]i by 92 nM and reduced the Δ[Ca2+]i induced by SP. A pertussis treatment (500 ng/ml‐24 h) did not modify the Δ[Ca2+]i induced by SP.

We conclude that SP, acting on a NK1 receptor, mobilizes cytosolic calcium from an intracellular calcium pool which can be partially depleted by thapsigargin. © 1994 Wiley‐Liss, Inc.
Microglial tyrosine phosphorylation systems in normal and degenerating brain
Authors: Karp Heather L. , Tillotson Meryl Lee , Soria Jennie , Reich Caroline , Wood John G.
Published: January 2005

Phosphotyrosine and protein tyrosine phosphatase antibodies have been used to assess the distribution and potential functions of tyrosine phosphorylation systems in normal brain and cell cultures, as well as in a model of neural degeneration. Western blot and immunohistochemical analysis showed that a panel of antiphosphotyrosine antibodies recognizing different tyrosine phosphorylated substrates all selectively labeled ramified microglia in sections of brain tissue. This significantly extends our previous observation (GLIA 2:412‐419, 1989) that a single, limited, phosphotyrosine antibody served as a histological marker for microglia. The present results show that tyrosine phosphorylation of a variety of substrates is quantitatively enriched in microglia compared to other neural cell types. We also show that the protein tyrosine phosphatase, CD45, is constitutively expressed by ramified microglia in vivo and by ameboid microglia in vitro. Thus, the major enzymes constituting tyrosine phosphorylation systems are present in normal microglia. Neuronal degeneration in the trigeminal nucleus, caused by a introduction of the neurotoxic lectin, ricin, into the peripheral nerve, is accompanied by a robust upregulation of phosphotyrosine signal in ramified microglial adjacent to the nucleus and in ameboid microglia in the degenerating nucleus. The presence of phosphotyrosine in ramified microglia is consistent with a role for tyrosine phosphorylation systems in the activation of microglia and in the signaling events accompanying conversion of resting microglia to the ameboid form. © 1994 Wiley‐Liss, Inc.
Social and environmental factors and depression in old age
Authors: Pahkala K.
Published: January 2005

This community‐based epidemiological study is concerned with relationships between social and environmental factors and depression in a Finnish population aged 60 years or over. A greater proportion of depressed than non‐depressed men had retired and did not work at all. The occurrence of depression in both sexes was related to retirement because of sickness rather than age, a small number of rooms in their homes, low numbers of hobbies, lack of intimate friendships, and the occurrence of many long‐standing and current social stress factors. Positive associations were also found in the men between the occurrence of depression and moving due to poor health, widowed or divorced marital status, being frequently alone and the fear of death, while a positive relationship was found between the occurrence of depression and low social participation in the women. In addition, the depressed women felt that elderly people were not appreciated. Also, the depressed women felt their relationships with their spouse, children, daughters‐in‐law and friends to be more distant than did their non‐depressed counterparts. This finding suggests that family dynamics plays an important role in depression in elderly women.
Capgras delusion in the elderly: The evidence for a possible organic origin
Authors: Förstl Hans , Almeida Osvaldo P. , Iacoponi Eduardo
Published: January 2005

We report the case of a 77‐year‐old right‐handed woman with early dementia of the Alzheimer type who developed the paranoid delusion that her husband had been replaced by an imposter (Capgras phenomenon). Her CT scan showed mild generalized cortical atrophy of the parieto‐occipital cortex. We reviewed the cases of 45 patients over 60 years who showed a Capgras delusion. Twenty‐five suffered from dementia or other chronic organic mental disorders, 20 were paranoid, 14 were at least moderatley depressed and 12 disorientated. CT scans (reported in 17 cases) showed global cerebral atrophy in 12 patients. Right hemisphere infarcts have been described in two elderly patients with Capgras delusions. Focal brain atrophy in Alzheimer type dementia has hitherto not been reported in association with this delusional symptom. We conclude from these observations that marked cerebral lesions and specific neuropsychological deficits are not required for the development of the Capgras phenomenon, which can occur in various functional or organic psychosis of old age.
Psychiatric presentation of intracranial tumour in the elderly
Authors: Fulton J. D. , Duncan G. , Caird F. I.
Published: January 2005

Fourteen patients aged 66–87 years are described, in whom major psychiatric problems dominated the presentation of intracranial tumour. Six had initially been referred to psychogeriatricians and eight to geriatricians. All showed intellectual failure, developing over a few weeks or months, with failure of self‐care, and a variety of disturbances of behaviour. Four had undoubted and two possible seizures. Their mental state was described as facile, or slow, with relatively unimpaired memory when it could be tested. Four were inaccessible or mute. Abnormal neurological signs were absent in two, but included unilateral or bilateral hypertonia and hyperreflexia in most; the plantar responses were flexor in seven, equivocal in three, and extensor on one or both sides in four. Computed tomographic (CT) scans shows frontal or bifrontal tumours in 13, and one occipital lobe tumour. The corpus callosum was involved in eight. Ten tumours were considered to be high‐grade astrocytomas (proven by biopsy in three and autopsy in one); one patient had bifrontal metastatic tumours, and three had meningiomas, all of them successfully resected. Clinical diagnosis was difficult, but a CT scan is indicated in all patients with a short history of intellectual failure.
Ideomotor and ideational apraxia in alzheimer's disease
Authors: Lucchelli Federica , Lopez Oscar L. , Faglioni Pietro , Boller Francois
Published: January 2005

Ideomotor apraxia (IMA) and ideational apraxia (IA) were studied in 32 Alzheimer's disease (AD) patients and in 30 non‐demented elderly controls using a standardized apraxia battery. AD patients performed significantly worse than controls on all apraxia tests, and were more impaired when pantomiming movements than when imitating movements. IMA and IA scores correlated with severity of dementia as measured by the Mini‐Mental State Examination. Analysis of individual performances revealed dissociated apraxic disorders in four patients, which may be interpreted as a manifestation of focal damage to left hemisphere cortical systems involved in praxis. Furthermore, these results suggest a greater ideational than ideomotor defect in apraxic AD patients.
Network analysis of motor system connectivity in Parkinson's disease: Modulation of thalamocortical interactions after pallidotomy
Authors: Grafton Scott T. , Sutton James , Couldwell William , Lew Mark , Waters Cheryl
Published: January 2005

Structural equation modeling was used to examine functional interactions between cortical and subcortical motor areas in Parkinson's disease patients and normal subjects. Neuronal activity was defined by positron emission tomography (PET) imaging of regional cerebral blood flow (rCBF) during performance of movement and control tasks. Patients were scanned before and 8‐12 weeks after stereotactic unilateral left posterovental globus pallidotomy. Pallidotomy attenuates basal ganglion inhibition of thalamocortical neurons involved in motor control and reduces the severity of bradykinesia in Parkinson's disease patients. It was hypothesized that with surgery there would be a similar alteration in thalamocortical interactions as measured with PET rCBF. A path analysis model of cortical and basal ganglia circuitry (defined by anatomic and electrophysiologic connectivity) was used to estimate unidirectional path coefficients describing the magnitude of region to region interactions. The resultant interactions defined a composite task‐and disease‐specific functional network of connectivity. After pallidotomy, there were significant reductions in the strength of interactions between the globus pallidus projection to thalamus, and the thalamus, projection to mesial frontal motor areas, consistent with the presumed physiologic interactions of these areas. This modeling approach can identify regional interactions that are not always apparent in categorical comparisons of inmaging data. ©1994 Wiley‐Liss, Inc.
Entorhinal cortex pathology in Alzheimer's disease
Authors: van Hoesen Gary W. , Hyman Bradley T. , Damasio Antonio R.
Published: January 2005

The anatomical distribution of pathological changes in Alzheimer's disease, although highly selective for only certain brain areas, can be widespread at the endstage of the illness and can affect many neural systems. Propriety for onset among these is a question of importance for clues to the etiology of the disease, but one that is formidable without an experimental animal model. The entorhinal cortex (Brodmann's area 28) of the ventromedial temporal lobe is an invariant focus of pathology in all cases of Alzheimer's disease with selective changes that alter some layers more than others. The authors'findings reveal that it is the most heavily damaged cortex in Alzheimer's disease. Neuroanatomical studies in higher mammals reveal that the entorhinal cortex gives rise to axons that interconnect the hippocampal formation bidirectionally with the rest of the cortex. Their destruction in Alzheimer's disease could play a prominent role in the memory deficits that herald the onset of Alzheimer's disease and that characterize it throughout its course.
Feedforward and feedback inhibition of hippocampal principal cell activity evoked by perforant path stimulation: GABA‐mediated mechanisms that regulate excitability In Vivo
Authors: Sloviter Robert S.
Published: January 2005

Hippocampal field potentials evoked by paired‐pulse perforant path stimulation were used to identify normal feedforward and feedback inhibitory influences on hippocampal principal cells. Three distinct aspects of inhibitory function were identified in the dentate gyrus. They are: (1) first spike amplitude‐dependent inhibition of the second spike, which at low stimulus frequency is primarily feedback in nature; (2) frequency‐dependent inhibition of a single spike of the first spike of a pair, which occurs as stimulus frequency is increased from 0.1 to 1.0 Hz and which is primarily a reflection of feedforward inhibition; and (3) frequency‐dependent inhibition of the second spike that is relatively independent of first spike amplitude and probably due to a combination of feedforward and feedback mechanisms. The results indicate that granule cell recurrent inhibition alone, evoked at low stimulus frequency, is relatively brief and weak. At higher frequencies, probably more relevant to physiological activity, feedforward inhibitory activity is recruited. The combination of feedforward and feedback mechanisms results in strong, maximal duration, granule cell inhibition. Similar frequency dependence of inhibition was not seen in area CA1 in response to ipsilateral perforant path stimulation since low frequency stimulation did not evoke CA1 spikes. CA3 stimulation did evoke large contralateral CA1 population spikes, but paired‐pulse inhibition was weaker than that evoked by ipsilateral perforant path stimulation in terms of the duration of inhibition and the ability to suppress the development of epileptiform behavior. The identification of simple tests that reflect distinct inhibitory processes in vivo permits similar studies to be conducted in vitro to determine how to preserve inhibitory processes for cellular studies of normal and human epileptic tissue in which the state of excitatory–inhibitory balance is the subject. These results also form the basis for the interpretation of the following study (Sloviter, 1991), which addresses the relationship between selective dentate interneuron loss and the pathophysiology that accompanies it.