bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of the rat light neurofilament (NF‐L) gene promoter and identification of NGF and cAMP responsive regions
Authors: Reeben Mati , Neuman T. , Palgi J. , Palm K. , Paalme V. , Saarma M. 
Published: January 2005

AbstractWe have isolated a genomic DNA clone covering the coding and 14 kb upstream region of the rat light neurofilament (NF‐L) gene and sequenced 2.3 kb of its promoter. DNase I hypersensitive sites have been mapped in PC12 cells. For functional analysis of the NF‐L promoter, constructs carrying 38, 97, 407, 564, 650, 1,099, 1,660, 2,003 base pairs (bp) upstream region in front of the chloramphenicol acetyltransferase (CAT) reporter gene were tested for their capability to direct CAT expression after transient transfection into various cell lines. Similar CAT activities were recorded both in rat pheochromocytoma (PC12) and mouse neuroblastoma N115 cells and also in several nonneural cell lines (HeLa, C127, NIH 3T3). Regions responsible for the basic promoter activity were located between −407 and +75 bp from the transcription initiation site. The NGF‐responsive element was located between −38 and +75 bp, and sequence −97 to −38 was found to contain a functional cAMP‐responsive element. In PC12 cells in which nerve growth factor (NGF) induces neurite outgrowth and NF‐L transcription, NF‐L promoter‐driven CAT expression was stimulated up to 12‐fold within three days of NGF treatment, whereas epidermal growth factor (EGF) had no effect. Rat NF‐L promoter contained Sp1, AP‐2 and CGCCCCCGC elements. In PC12 cells, NGF transiently induced the binding of transcription factors to the deoxyoligonucleotide probes containing the binding sites of these elements. The role of these factors in NF‐L gene transcriptional induction by NGF in PC12 cells is discussed. © 1995 Wiley‐Liss, Inc.
Tenotomy prevents the functional improvement of a muscle reinnervated with a chronically severed nerve
Authors: Carobi Clara , Brunetti O. 
Published: January 2005

AbstractDuring the early stages of nerve implantation, we followed the dynamic properties of the lateral gastrocnemius muscle of the rat, reinnervated with an acutely or chronically severed peroneal nerve. The aim of this study was to ascertain whether (1) the better functional recovery of a muscle reinnervated by a chronically severed foreign nerve is present from the onset of reinnervation, and (2) whether such functional improvement is due to the conditioning lesion effect. Our results indicate that better functional recovery is already apparent one week after nerve implantation, and it is due to the conditioning lesion effect, since tenotomy prevents such improvement. The tenotomy effect underlines the fact that some environmental factors concerning the target tissue, and not only the predegenerated nerve, are involved in the conditioning effect. © 1995 Wiley‐Liss, Inc.
Modulation of Schwann cell P0 glycoprotein and galactocerebroside by the surface organization of axolemma
Authors: Calderon Reyna O. , Maggio B. , Neuberger T. J. , Devries G. H. 
Published: January 2005

AbstractThe nature of the axon signal for the induction of proliferation and differentiation of peripheral glial cells is still unknown. Besides the existence of interactions among surface molecules the cellular responses can also be regulated by physicochemical parameters of the membrane. We have previously reported that planar axolemma monolayers coated on glass coverslips at different defined surface molecular packing affected the Schwann cell (SC) morphology and their proliferative response (Calderon et al.: J Neurosci Res 34:206–218, 1993). In this paper we report that relative to SC cultured on uncoated coverslips, the level of expression of both glycoprotein P0 and galactocerebroside (GC) (as revealed by immunofluorescence) was increased 2–4 times in SC cultured on axolemma monolayers with either high or low molecular packing. However, the cellular distribution of these antigens was profoundly influenced by the molecular packing density of the axolemma monolayer. SC cultured on an axolemma monolayer at high molecular packing showed preferential expression of P0 at the SC surface whereas GC was concentrated intracellularly. On the other hand, SC grown on an axolemma monolayer at low molecular density GC showed preferential expression at the cell surface whereas P0 was concentrated intracellularly. © 1995 Wiley‐Liss, Inc.
Expression and distribution of phosphorylated MAP1B in growing axons of cultured hippocampal neurons
Authors: Boyne L. J. , Martin K. , Hockfield S. , Fischer Itzhak 
Published: January 2005

AbstractMicrotubule associated proteins (MAPs) interact with tubulin to modulate neurite stability and growth during development. The phosphorylated form of one of these MAPs, MAP1B (MAP1B‐P) is hypothesized to be of particular importance for the regulation of neurite outgrowth. To investigate the mechanisms by which MAP1B and MAP1B‐P contribute to this regulation, we used a new antibody against an isoform of MAP1B‐P to determine its pattern of expression during neuronal development in vitro. We examined cultured hippocampal neurons because these provide a well‐established system to evaluate the development of axons and dendrites. MAP1B, MAP1B‐P and MAP2 colocalized to the cell bodies and minor processes during the first 24 hours of culture, but MAP1B‐P also extended well into the growth cones. As neurite outgrowth and differentiation proceeded, MAP1B and MAP1B‐P became localized to the cell bodies and axons, and MAP2 to the cell bodies and dendrites. After 3 days, MAP1B‐P declined in the cell body and was segregated to the distal axon; MAP1B remained in the cell body, but was also concentrated in the distal axon. Over 5–9 days in culture, MAP1B‐P levels decreased and became undetectable; MAP1B levels decreased later (19–23 days). MAP2 levels, however, remained high through the entire culture period in cell bodies and dendrites. These results are consistent with the hypothesis that MAP1B‐P plays an important role in the initiation and elongation of axons by regulating the dynamics of microtubules near the growth cone: MAP1B‐P expression is greatest during the period of active neurite extension, is particularly prominent in growth cones where axon outgrowth is most active, and decreases along with the decline in active axon extension. © 1995 Wiley‐Liss, Inc.
Cortical astroglial conditioned medium induces in vitro radial‐like forms
Authors: Colombo J. A. , Napp M. , Puissant V. 
Published: January 2005

AbstractCerebral cortex and striatal cell dissociates obtained from rat fetuses (E17) were subcultured and enriched in astroglial cells before being grown in regional (cerebral cortex, striatum) astroglial conditioned media (CM) or defined basal medium. Incidence of radial‐like astroglia (vimentin + or glial fibrillary acid protein, GFAP + ) and length of processes in cortical cell subcultures showed a greater increase when exposed to cerebral cortex CM than to striatal CM or basal medium. Stellate (GFAP + ) forms prevailed in subcultures grown in basal medium while striatal cells exposed to CM of either origin remained undifferentiated. Additionally, cultures were treated with various concentrations of cAMP (0.25 and 0.5 mM) and calcitonin gene related peptide (CGRP) (0.1, 0.5, and 1.0 μ). Under these conditions CM‐exposed cultures (with predominant “radial‐like” forms) did not increase stellate glial numbers, while fetal calf serum (FCS)‐exposed cultures (morphologically undifferentiated) underwent significant degrees of stellate transformation. When CM‐exposed cultures were shifted to FCS supplemented basal medium for 24–48 hr and then to basal medium alone prior to treatment, cAMP and CGRP were effective in transforming flat astroglia into stellate morphology. Results are indicative of the existence of astroglial diffusible factors affecting the in vitro expression of astroglial morphotypes from the cerebral cortex. Previous exposure to CM interferes with cytoskeletal astrocytic changes induced by cAMP and CGRP. It is speculated that astroglial factors could act in vivo to maintain the expression of radial‐like cells during early developmental stages of the cerebral cortex, but it would not be effective in E 17 striatum. It is also suggested that transformation of radial glia into astrocytes may require previous dedifferentiation of the cytoskeleton. © 1995 Wiley‐Liss, Inc.
Adult rat optic nerve oligodendrocyte progenitor cells express a distinct repertoire of voltage‐ and ligand‐gated ion channels
Authors: Borges K. , Wolswijk G. , Ohlemeyer C. , Kettenmann H. 
Published: January 2005

AbstractCultured oligodendrocyte progenitor cells derived from the developing central nervous system (CNS) express a pattern of ion channels that is distinct from mature oligodendrocytes and other cell types of the CNS. In the present study, we used the whole‐cell patch‐clamp technique and the fura‐2‐based Ca++ imaging system to study the ion channel expression of oligodendrocyte progenitor cells derived from the optic nerves of adult rats. We found that the adult oligodendrocyte progenitor cell membrane is dominated by K+ currents, both delayed outward and inward rectifying. The inwardly rectifying K+ currents were often as large as the outward delayed rectifying K+ currents. The delayed rectifying outward currents were partially blocked by 50 mM tetraethylammonium or 1 mM 4‐aminopyridine, but not by 2 or 5 mM BaCl2. This suggests that the delayed rectifier channels expressed by adult progenitor cells are different from those expressed by perinatal cells. Most adult oligodendrocyte progenitor cells showed no or only small A‐type K+ currents. Both Ca++ and Na+ channels were also detected in these cells. Furthermore, adult progenitor cells responded to the neurotransmitters GABA and kainate and the pharmacology of these responses indicated that these cells express GABAA receptors and kainate receptors that are Ca++ ‐permeable. Our study suggests that adult oligodendrocyte progenitor cells are electrophysiologically distinct and that these cells share electrophysiological characteristics with both perinatal progenitor cells and immature oligodendrocytes. © 1995 Wiley‐Liss, Inc.
Selection of stably transfected cells expressing a high level of fetal muscle nicotinic receptors
Authors: Chen Q. , Fletcher G. H. , Steinbach J. H. 
Published: January 2005

AbstractWe had earlier found that the numbers of mouse muscle nicotinic receptors expressed on the surface of individual cells of a stably transfected clonal line of quail fibroblasts varied from cell to cell (Kopta and Steinbach: J Neurosci 14:3922–3933, 1994). We have now used repeated selective passages of these clonal cells to produce a population of cells which expresses a greater and more uniform number of surface receptors per cell. The increased level is stable over many cell divisions, and over many half‐lives for the metabolic degradation of the surface receptors. Selection was performed by adhesion to a surface coated with a monoclonal antibody to a surface epitope on the muscle receptor, followed by expansion of the most tightly attached population of cells. Studies of the selected cells show that the surface receptors contain all four subunits of the muscle nicotinic receptor, and the functional properties of the receptors appear normal. The metabolic stability of the surface receptors is not altered, while the amount of mRNA for the subunits is increased in the selected population of cells. These observations indicate that the more likely reason for increased expression is a transcriptional effect, and that translational or posttranslational changes are unlikely. © 1995 Wiley‐Liss, Inc.
Differential expression of neurotensin receptor mRNA in the dopaminergic cell groups of the rat diencephalon and mesencephalon
Authors: Nicot A. , Rostène W. , Bérod A. 
Published: January 2005

AbstractSeveral lines of evidence support interactions between neurotensin (NT) and dopaminergic (DAergic) neurons in the brain. In order to obtain further knowledge about the anatomical substrate for such interactions, the distribution of cells expressing the cloned neurotensin receptor (NTR) mRNA was examined in relation to tyrosine hydroxylase (TH) mRNA‐expressing cells within different subnuclei of the diencephalon and ventral mesencephalon of the male rat. In situ hybridization was performed on consecutive sections labeled with 33P‐labeled oligonucleotide probes. In the hypothalamus, NTR mRNA signals were mostly found in the suprachiasmatic, dorsomedial, dorsal premammillary, and supramammillary nuclei. On the other hand, DAergic cells of the periventricular nucleus of the hypothalamus and dorsal aspect of the arcuate nucleus, revealed by TH in situ hybridization, did not exhibit NTR mRNA even though dense NT binding sites have been previously described in this nuclei. In the zona incerta, TH mRNA‐containing cells were concentrated in the medial part, with little overlap with NTR mRNA‐expressing cells located mainly in its mediolateral extent. In contrast, the distribution of both markers was superimposable within the different subdivisions of the ventral tegmental area and substantia nigra, as previously suggested, but also in the retrorubral field. These anatomical data further support the NT‐dopamine interactions on both mesocorticolimbic and nigrostriatal DAergic systems. Moreover, the results suggest that diencephalic DAergic neurons do not synthesize the cloned NTR mRNA or express it at considerably lower levels than DAergic mesencephalic cells. © 1995 Wiley‐Liss, Inc.
Effect of diet on tissue protease activity
Authors: Benuck Myron , Banay‐Schwartz M. , Deguzman T. , Vizi E. S. , Kekes‐Szabo A. , Lajtha A. 
Published: January 2005

AbstractRats 1,3,12, and 24 months old were fed diets low in protein (8% casein), and proteolytic activity in tissue from brain, liver, and lung was determined. After a low‐protein diet was fed for 4 weeks to 1‐month‐old rats, there was a significant increase in cathepsin D activity in liver, and calpain activity was increased in lung. Little change was seen in proteolytic activity in brain. In 12‐month‐old rats, there was an increase in cathepsin D activity in brain and liver. In 24‐month‐old rats, cathepsin D activity in the liver and calpain activity in lung were increased. There was no change in proteolytic activity in the brain. When animals were fed diets supplemented with fatty acids or antioxidants for 2 months, in 3‐month‐old rats calpain activity was increased in brain but decreased in lung. Cathepsin D activity was significantly increased in young and adult animals in brain and in liver. These observations suggest that diet changes result in significant alteration in tissue calpain and cathepsin D levels, and possibly activity, in vivo. Generally, changes are greater for cathepsin D than for calpain, and are smaller in brain than in other tissues. © 1995 Wiley‐Liss, Inc.
Establishment and characterization of a multipotential neural cell line that can conditionally generate neurons, astrocytes, and oligodendrocytes in vitro
Authors: Nakafuku Masato , Nakamura S. 
Published: January 2005

AbstractIn the mammalian central nervous system (CNS), multipotential neural stem cells in the neuroepithelium generate the three major types of neural cells, namely, neurons, astrocytes, and oligodendrocytes. To explore the molecular mechanisms underlying proliferation and differentiation of these neural stem cells, we established a cell line named MNS‐57 from the embryonic day 12 rat neuroepithelium by introducing the mycer fusion gene, in which c‐myc can be conditionally activated by adding oestrogen to the culture medium. MNS‐57 cells expressed nestin, vimentin, and the RC1 antigen, which are potential markers for neural stem cells. We show that under particular culture conditions, MNS‐57 cells can conditionally generate neurons, astrocytes, and oligodendrocytes in vitro, indicating that they are likely to originate from multipotential neural stem cells. Incubating MNS‐57 cells with either oestrogen, which activates mycer, or growth factors such as basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF) stimulated their growth, and the combination of oestrogen and bFGF (or EGF) had a synergistically stronger mitogenic effect than the single factors. Furthermore, both c‐myc activation and bFGF appeared to be necessary for the differentiation of MNS‐57 cells, and only when stimulated by both signals simultaneously, the cells committed to generating multiple neural cell types. Thus, the property of the cell line is unique in that its differentiation into neurons and glia can be conditionally manipulated invitro in an exogenous signal‐dependent manner. We propose that the cell line described here will provide an useful in vitro model to understand genetic and environmental mechanisms that control the generation of neural cell diversity in the CNS. © 1995 Wiley‐Liss, Inc.
Excitatory amino acid‐induced AP‐1 DNA binding activity in müller glia
Authors: López‐Colomé A. M. , Murbartián J. , Ortega Arturo 
Published: January 2005

AbstractThe effect of L‐glutamate (L‐Glu) and its structural analogs N‐methyl‐D‐aspartate (NMDA), quisqualate (QA), and kainate (KA) on the DNA binding activity of the Activator Protein 1 (AP‐(1) and the Ca2+/cAMP Responsive Element Binding Protein (CREB) families of transcription factors was examined in cultured chick retinal Müller glia cells. L‐Glu, NMDA, and KA evoked a dose and time dependent increase in AP‐1 DNA binding activity and had no effect on CREB binding. The order of potency for stimulating AP‐1 DNA binding was NMDA≥Glu>KA>>QA. L‐Glu responses were partially blocked by 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione (CNQX) and by 3‐[RS)‐2‐carboxypiperazin‐4‐yl)]‐propyl‐l‐phosphonate (CPP) indicating that the increase in DNA binding is mediated both by an a‐amino‐3‐hydroxy5‐methyl‐4‐isoxazolepropionate (AMPA)/low affinity KA and a NMDA subtypes of L‐Glu receptors. Since Müller glia L‐Glu receptors are probably mediators of the efficacy of the excitatory transmission in the retina, the present findings suggest that a stimulustranscription coupling triggered by L‐Glu in the glial cells might have a role in the long‐term modulation of these synapses. © 1995 Wiley‐Liss, Inc.
In vitro glial responses to nerve growth factor
Authors: Hutton L. A. , Perez‐Polo J. R. 
Published: January 2005

AbstractNerve growth factor (NGF) stimulates expression of the low affinity neurotrophin receptor p75NGFR mRNA in primary cultures of neonatal rat cortical type I astrocytes. Nerve growth factor treatment altered glial morphology in glial fibrillary acidic protein positive (GFAP+) cell cultures derived from newborn (P0) and 3‐day‐old (P3) rat pups. When P0‐ or P3‐derived primary glial cultures were serum‐deprived, in the presence of 200 pM NGF for 5 days, the flat polygonal glia present in culture assumed a fibrous morphology, an effect not seen in the untreated serum‐deprived controls. The NGF effect on astrocytic morphology was blocked by continuous serum treatment. Nerve growth factor did not stimulate astrocytic proliferation under these culture conditions, as assayed by cell cycle analysis using 3H thymidine autoradiography. P0‐derived primary glial cultures expressed the signal transducing neurotrophin receptors p145trkB and p140trka as determined by reverse transcription‐polymerase chain reaction (RT‐PCR). RT‐PCR products were identified by sequencing or restriction enzyme analysis. Astrocytes internalized 125I‐NGF at 37°C but not at 4°C, consistent with energy requirements for internalization. Also, internalization of 125I‐NGF was abolished by the addition of a 300‐1,000‐fold excess of unlabeled NGF. Thus, astroglial cells in culture internalize NGF through a specific receptor‐mediated process, express trkA and full‐length trkB mRNAs at low levels, and respond to exogenous NGF by expressing a fibrous morphology under serum‐free culture conditions. © 1995 Wiley‐Liss, Inc.
A morphometric analysis of bipolar and multipolar TH‐IR neurons treated with the neurotoxin MPP+ in co‐cultures from mesencephalon and striatum of embryonic C57BL/6 mice
Authors: Koutsilieri E. , Chen T.‐S. , Kruzik P. , Rausch W.‐D. 
Published: January 2005

AbstractMesencephalic cultures contain two morphologically different tyrosine hydroxylase (TH)‐immunoreactive (IR) neurons, fusiform bipolar, and pyramidal multipolar, which project to different anatomical structures (ventral striatum and neostriatum). The possibility of functional difference of these cells in Parkinson's disease led us study the effect of 1‐methyl‐4‐phenylpyridinium (MPP+) on them. Survival and morphology of the two groups was studied in dissociated co‐cultures from mesencephalon and striatum of embryonic C57BL/6 mice. Cells were grown at first in serum containing medium and then in serum free medium supplemented with hormones. Cultures were exposed to different concentrations of MPP+ on day 9 and 13 for 24 hr. They were fixed and stained, with an anti‐TH antibody. 0.1‐1.0μM MPP+ caused a dramatic reduction of the total area of TH‐IR neurons. At 0.1 μM MPP+ some area was reduced, at 0.5 μM it appeared similar to controls, and decreased further at 1.0 μM. The relation of soma to total area showed that the decrease of the neuronal size was mainly due to the degeneration of the neuronal processes. The length of neuronal tree as well as the number of terminal segments were reduced dose dependently when cells were treated with the toxin. Similar results were obtained for bipolar and multipolar neurons. A significant difference in the decrease in total area was observed between the two age groups when cells were treated with MPP+, as older cells appeared to be more sensitive. When other parameters were checked no apparent difference was present. © 1995 Wiley‐Liss, Inc.