bluuebunny/crossref_metadata_2025_split huggingface dataset:
Normal distribution of alpha 2‐adrenoceptors in the rat spinal cord and its modification after noradrenergic denervation: A quantitative autoradiographic study
Authors: Roudet C. , Mouchet P. , Feuerstein C. , Savasta M. 
Published: January 2005

AbstractThe distribution of alpha 2 (α2)‐adrenoceptors along cervical, thoracic, lumbar, and sacral segments of the spinal cord of normal rats has been studied by quantitative autoradiography using the specific α2‐antagonist [3H]rauwolscine as a ligand. In addition, the influence of noradrenergic (NA) denervation [obtained either by complete transection of the spinal cord at vertebrae level T8–T9 or by selective lesion of NA spinal cord system carried out by intracisternal injection of 6‐hydroxydopamine (6‐OHDA)] on eventual variations of α2‐adrenoceptor density at spinal cord target cells was studied in parallel.In control rats, the quantitative analysis of α2‐adrenoceptor densities revealed the presence of these receptors throughout the whole gray matter with a preferential location in the superficial dorsal horn. This pattern was the same at all rostro‐caudal levels of the cord and appeared very well correlated with the distribution of NA terminals revealed by immunohistochemistry, particularly in the supeficial layers of the dorsal horn.After total transection of the spinal cord (caudally to the section) and 6‐OHDA‐induced lesion, an increase of α2‐adrenoceptor density was mainly observed within the distal dorsal horn thus evidencing supersensitivity in this area, while modifications were not detectable in other regions of the spinal gray matter, except at the lumbar level where other dorsal, central, and intermediate zones were significantly enriched. © 1994 Wiley‐Liss, Inc.
Isoprenylation of brain 2′,3′‐cyclic nucleotide 3′‐phosphodiesterase modulates cell morphology
Authors: De Angelis D. A. , Braun P. E. 
Published: January 2005

AbstractCNP (2′,3′‐cyclic nucleotide 3′‐phosphodiesterase) is the earliest myelination specific polypeptide to be synthesized by oligodendrocytes (OLs). When non‐myelinating “naive” cells are transfected with the rat CNP cDNA, CNP accumulates intracellularly in a punctate manner, as well as at the plasma membrane. Filopodia and processes, like those of OLs become elongated and more numerous, and are filled with this protein. Post‐translational isoprenylation of the terminal C‐T‐I‐I sequence with either farnesyl or geranylgeranyl is essential for this phenomenon. In contrast, the non‐isoprenylated C397S mutant is homogeneously distributed throughout the cytoplasm and does not markedly affect cellular morphology. We have sythesized CNP and the C397S mutant in vitro and have shown that isoprenylation is essential for the binding of newly synthesized CNP to myelin. © 1994 Wiley‐Liss, Inc.
GRASP: A novel heparin‐binding serum glycoprotein that mediates oligodendrocyte‐substratum adhesion
Authors: Schirmer E. C. , Farooqui J. , Polak P. E. , Szuchet S. 
Published: January 2005

AbstractCell‐substratum adhesion plays a crucial part in the cascade of events that control growth or turn on and consummate a differentiation program. We are investigating the molecular basis of oligodendrocyte (OLG) cytodifferentiation, employing pure cultures of OLGs isolated from postmyelination brains. We have shown that such OLGs will regenerate in vitro and reenact the ontogenic development of myelin, but to do so they need a signal. Adherence to a polylysine surface in the presence of 20% horse serum generates such a signal. Among the events that are turned on upon OLG adhesion is the phosphorylation of myelin basis protein; no such phosphorylation takes place in the non‐adhered cell. We postulated that horse serum provides an adhesion molecule. Laminin, fibronectin, collagen and native vitronectin failed to replace horse serum. Hence, we set out to fractionate horse serum by screening with an adhesion assay. We report here the identification, purification and partial characterization of a novel, heparin‐binding horse serum glycoprotein that we have termed Glycine‐Rich Adhesion Serum Protein—GRASP—to stress the fact that this protein has a high content of glycine and functions, in vitro, as an adhesion molecule for OLGs. There is 61% similarity at the N‐terminus between GRASP and histidine‐rich glycoprotein precursor (HRGP), an α2‐glycoprotein from human plasma. However, our data suggest that GRASP is not the horse serum homolog of HRGP. First, the two Gps are functionally distinct: HRGP does not promote the adhesion of OLGs. Second, the amino acid compositions differ significantly, e.g., GRASP is not histidine‐but rather glycine‐rich. Third, the region of sequence similarity between GRASP and HRGP is conserved throughout the cystatin superfamily. Fourth, anti‐Gp55 polyclonal Abs recognize a similar set of polypeptides—save for slight differences in Mr—in human serum as in horse serum, indicating that HRGP and GRASP are two distinct but related proteins and are both present in human and horse sera. GRASP is a dimer/trimer of seemingly identical subunits of Mr ⌣︁ 55,000; the native protein has an Mr × 10−3 ⌣︁ 120–140, of which 24–27% is contributed by carbohydrate. Using GRASP as a substratum allows the growth of OLGs in serum‐free medium. GRASP is as good an effector of myelin basic protein phosphorylation as 20% horse serum. We conjecture that the mechanism of GRASP function features: (1) exposure of a cryptic sequence—after a change in conformation induced upon binding to polylysine—with affinity for an OLG signal‐transducing receptor; and (2) interaction of its heparin‐binding domain with OLG surface heparan sulfate proteoglycans and/or the aforementioned receptor. © 1994 Wiley‐Liss, Inc.
Synapsin I expression in spinal cord neurons during chick embryo development
Authors: Plateroti M. , Vignoli A. L. , Biagioni S. , di Stasi A. M. M. , Petrucci T. C. , Augusti‐Tocco G. 
Published: January 2005

AbstractThe cellular distribution of synapsin I in chick spinal cord has been examined during embryo development and in cultured neurons from different developmental stages. Using immunocytochemical methods we have observed that synapsin I appears lightly detectable in spinal cord of embryonic day (E)5–E8 embryos when the motor neurons have already established functional contacts with muscle fibers, and increases at E9. Until E8 synapsin I immunoreactivity appeared mainly localized in the gray matter of spinal cord; immunostaining of white matter becomes clearly evident only at E9. These observations indicate that synapsin I expression and possibly its transport to the nerve terminals may be stimulated by sequential signals. The cellular distribution of synapsin I observed in vivo is maintained in E8 and E9 spinal cord neuron cell cultures. In fact, in E8 cultured neurons, synapsin I immunostaining is observed only in the cell body, while in E9 cultured neurons both cell body and fibers are stained. The addition of muscle extracts to E8 cultures induces synapsin I decoration of fibers similar to that observed in E9 cultured neurons. Indeed Western and Northern blot analysis and in situ hybridization demonstrate an increase of synapsin I and its mRNA in spinal cord neurons kept in the presence of muscle extracts. These data suggest that synapsin I expression, as previously reported for other neuronal markers, can be modulated by soluble factors present in target cells. © 1994 Wiley‐Liss, Inc.
Role of GABAB receptors in intracellular Ca2+ homeostasis and possible interaction between GABAA and GABAB receptors in regulation of transmitter release in cerebellar granule neurons
Authors: Kardos J. , Elster L. , Damgaard I. , Krogsgaard‐Larsen P. , Schousboe A. 
Published: January 2005

AbstractThe expression of GABAB receptors in cultured mouse cerebellar granule cells was investigated in binding experiments using [3H](S, R)‐baclofen as well as in functional assessment of the ability of (R)‐baclofen to interact with depolarization (15–40 mM KCI) coupled changes in intracellular Ca2+ homeostasis and neurotransmitter release. In the latter case a possible functional coupling between GABAA and GABAB receptors was investigated. The binding studies showed that the granule cells express specific binding sites for (R)‐baclofen. The number of binding sites could be increased by exposure of the cells to the GABAA receptor agonist THIP (4,5,6,7‐tetrahy‐droisoxazolo[5,4‐c]pyridin‐3‐ol) during the culture period. Pretreatment of the neurons with pertussis toxin showed that the GABAB receptors are coupled to G‐proteins. This coupling was, however, less pronounced when the cells had been cultured in the presence of THIP. When 45Ca2+ uptake was measured or the intracellular Ca2+ concentration ([Ca2+]i) determined using the fluorescent Ca2+ chelator Fluo‐3 it could be demonstrated that culturing the neurons in THIP influences intracellular Ca2+ homeostasis. Moreover, this homeostasis was found to be functionally coupled to the GABAB receptors as (R)‐baclofen inhibited depolarization‐induced increases in 45Ca2+ uptake and [Ca2+]i. (R)‐Baclofen also inhibited K+‐induced transmitter release from the neurons as monitored by the use of [3H]D‐aspartate which labels the neurotransmitter pool of glutamate. Using the selective GABAA receptor agonist isoguvacine it could be demonstrated that the GABAB receptors are functionally coupled to GABAA receptors in the neurons leading to a disinhibitory action of GABAB receptor agonists. © 1994 Wiley‐Liss, Inc.
Partial purification of a novel mitogen for oligodendroglia
Authors: Kreider Barbara Q. , Grinspan J. B. , Waterstone M. B. , Bramblett G. T. , Ances B. , Williams M. , Stern J. , Lee V. M.‐Y. , Pleasure D. 
Published: January 2005

AbstractA protein with a MWapp of 50–70 kDa isolated from the salt extract of crude membranes from neonatal rat brain increases the numbers of oligodendroglia in mixed glial cultures prepared from neonatal rat cerebral white matter. After partial purification by ion exchange and gel exclusion chromatography, and elution from an SDS‐polyacrylamide gel, this protein ( “oligodendroglial trophic factor,” OTF) elicited half‐maximal oligodendroglial recruitment at a concentration of 5 ng/mL. OTF is a mitogen for oligodendroglia, and to a lesser extent, for oligodendroglial progenitor (O2A) cells, but does not stimulate proliferation of astroglia, Schwann cells, or endoneurial fibroblasts. OTF, unlike platelet‐derived growth factor (PDGF), is not an oligodendroglial survival factor. Antibodies against PDGF and basic fibroblast growth factor (bFGF) do not interfere with the accumulation of oligodendroglia induced by OTF. When OTF is given simultaneously with either PDGF or bFGF, there is an additive increase in the numbers of cells of the oligodendroglial lineage. © 1995 Wiley‐Liss, Inc.
Transforming growth factor‐β1 inhibits the proliferation of rat astrocytes induced by serum and growth factors
Authors: Vergelli M. , Mazzanti B. , Ballerini C. , Gran B. , Amaducci L. , Massacesi Luca 
Published: January 2005

AbstractA number of cytokines and growth factors may affect astrocyte proliferation and functions. Transforming growth factor‐β1 (TGF‐β1) is a pleiotropic cytokine which exerts multiple effects on growth and differentiation of different cell types. TGF‐β1 is present in low amounts in the normal brain. TGF‐β1 gene expression, however, is increased in the central nervous system (CNS) in several pathological conditions. In this study we examined the in vitro effects of TGF‐β1 on the proliferative response of rat astrocytes to serum and growth factors. Astrocyte cultures were established from the cerebellum and cortex of newborn Lewis rats. The proliferative response of these cultures to serum and growth factors [platelet‐derived growth factor (PDGF), basic fibroblast growth factor (bFGF), epidermal growth factor (EGF), insulin‐like growth factor 1 (IGF‐1), IGF‐2, interleukin 1 (IL‐1)] was studied by [3H]‐thymidine incorporation test in the presence or absence of TGF‐β1. TGF‐β1 significantly inhibited the proliferative response of astrocyte cultures to both autologous and heterologous serum. In addition, a strong inhibition of bFGF‐, EGF‐, and PDGF‐induced proliferation was observed. The effect of TGF‐β1 on the proliferative response to IL‐1 was less evident but still significant. No effect was observed when TGF‐β1 was added to IGF‐1 and IGF‐2 stimulated cultures. These data confirm previous reports showing a down‐regulating activity of TGF‐β on astrocyte proliferation and suggest that this cytokine may play physiological and pharmacological roles in the regulation of reactive astrocytosis in the CNS. © 1995 Wiley‐Liss, Inc.
Synaptic vesicle‐associated glutamate decarboxylase: Identification and relationship to insulin‐dependent diabetes mellitus
Authors: Nathan B. , Floor E. , Kuo C.‐Y. , Wu Jang‐Yen 
Published: January 2005

AbstractGlutamic acid decarboxylase (GAD) catalyzes the biosynthesis of the inhibitory neurotransmitter γ‐aminobutyric acid (GABA). GAD has been suggested as an autoantigen in insulin‐dependent diabetes mellitus and stiff‐man syndrome. Recently, three forms of membrane‐associated GAD (MGAD) have been characterized in porcine brain, but the subcellular localization and function of these proteins are unknown. We present evidence that GAD activity is associated with synaptic vesicles from porcine brain. These vesicles contain a 60 kDa protein recognized by serum from patients with insulin‐dependent diabetes mellitus, probably MGADII, as shown by subcellular fractionation and immunoblotting. These results raise the possibility that the association of MGADII with synaptic vesicles may be crucial for its role as an autoantigen in insulin‐dependent diabetes mellitus. © 1995 Wiley‐Liss, Inc.
Expression of bcl‐2 inhibits necrotic neural cell death
Authors: Kane D. J. , Örd T. , Anton R. , Bredesen Dale E. 
Published: January 2005

AbstractCell death has been described as either apoptotic, in which the cell actively participates, or necrotic, in which the cell is felt to be passive. The proto‐oncogene bcl‐2 has been shown to inhibit apoptosis in some hematopoietic and neural cells, by an unknown mechanism. We demonstrate that bcl‐2 inhibits the necrosis of neural cells induced by glutathione depletion. This finding demonstrates that bcl‐2 does not inhibit the cellular death program directly; rather, bcl‐2 modulates a cellular process that leads to apoptosis under some conditions but necrosis under others. © 1995 Wiley‐Liss, Inc.
Basic fibroblast growth factor down‐regulates myelin basic protein gene expression and alters myelin compaction of mature oligodendrocytes in vitro
Authors: Fressinaud C. , Vallat J. M. , Labourdette G. 
Published: January 2005

AbstractThe effects of basic fibroblast growth factor (bFGF) on myelin basic protein (MBP) gene expression and myelin‐like membrane formation were investigated in oligodendrocyte cultures containing mainly mature oligodendrocytes expressing MBP. These cultures were obtained by selective detachment of the cells of the oligodendrocyte lineage from 40‐day‐old mixed cultures derived from newborn rat brain. They were further purified by a 3‐day pretreatment with cytosine arabinoside (ARA‐C) in order to kill cycling cells. After withdrawal of ARA‐C, daily treatment of the cells with bFGF for 3 days induced a drastic decrease in MBP mRNA level compared to control cultures treated only with ARA‐C. Moreover, the percentage of oligodendrocytes labelled with anti‐MBP antibodies decreased by 50%, as well as that of oligodendrocytes expressing myelin oligodendrocyte glycoprotein (MOG), whereas proteolipid protein (PLP) immunolabelled cells were less affected. At the ultrastructural level, myelin‐like membranes were still abundant in the ARA‐C‐and bFGF‐treated cultures, but they were conspicuously uncompacted compared to cultures only pretreated with ARA‐C. These results bring the first evidence that bFGF is able to down‐regulate myelin protein gene expression in mature oligodendrocytes and to alter myelin structure. They imply that if bFGF is secreted after a demyelinating lesion of the central nervous system (CNS), this plasticity of mature oligodendrocytes will allow final remyelination of axons to complete only after this factor has returned to low levels. © 1995 Wiley‐Liss, Inc.
Astrogliosis in culture. IV. Effects of basic fibroblast growth factor
Authors: Hou Y.‐J. , Yu A. C. H. , Garcia J. M. R. Z. , Aotaki‐Keen A. , Lee Y.‐L. , Eng L. F. , Hjelmeland L. J. , Menon V. K. 
Published: January 2005

AbstractPrevious studies have shown that the mechanical wounding of 3‐week‐old cultured rat astrocytes results in cell proliferation and hypertrophy resembling astrocyte responses to a brain injury in vivo. We now report the effects of basic fibroblast growth factor (bFGF) and an anti‐bFGF antibody on astrocyte morphology, proliferation, and migration following in vitro wounding of confluent secondary cultures. Addition of bFGF (20 ng/ml) to wounded cultures induced morphological changes characteristic of differentiation in wounded and nonwounded areas of the culture. Combined treatment with bFGF and an anti‐bFGF antibody (100 μg/ml) prevented this effect. Astrocyte proliferation along the edges of a scratch wound was at maximum 24 hr after wounding in cells growing in Eagle's minimum essential medium (EMEM) containing 10% serum. Low serum concentration and treatment with dibutyryl cyclic adenosine monophosphate (dbc‐AMP) reduced injury‐associated astrocyte proliferation. Addition of bFGF to cultures in EMEM with serum increased astrocyte proliferation at 18 and 24 hr after wounding. This effect was reduced considerably by treatment of cultures with bFGF in combination with an anti‐bFGF antibody. The combined treatment and the antibody alone reduced cell division to a level lower than in control cultures. Twenty‐four hr following wounding, astrocytes along the edges of the wound exhibited extension of thick, flat processes into the wound area. At 3 and 5 days after wounding, a bodily migration of astrocytes into the wounded area was observed. Addition of bFGF significantly increased astrocyte migration 1 day after wounding, with maximum effect on day 3 and no subsequent increase on day 5. A combination of bFGF and anti‐bFGF antibody as well as the antibody alone reduced astrocyte migration to a level lower than in controls. Immunohistochemical localization and isoform pattern of bFGF in astrocytes did not change with dbc‐AMP treatment or wounding. We conclude that mechanically wounded confluent astrocytes respond to bFGF added to the culture medium by enhancing cell division, differentiation, and migration. In addition, the results of the antibody treatment also suggest a role for endogenous bFGF in astrocyte proliferation and migration elicited by wounding in vitro. These results support the notion that in vivo, both bFGF released by injury and endogenous bFGF synthesized by astrocytes, contribute to the cellular responses that lead to astrogliosis. © 1995 Wiley‐Liss, Inc.
Effects of carbonic anhydrase II (CAII) deficiency on CNS structure and function in the myelin‐deficient CAII‐deficient double mutant mouse
Authors: Cammer Wendy , Zhang H. , Tansey F. A. 
Published: January 2005

AbstractIn the choroid plexus carbonic anhydrase II (CAII) supports the transport of bicarbonate ions, sodium ions, and water from blood to the CSF, and in the myelin sheath CAII supports compaction of myelin by stimulating cotransport of ions and water out from between the myelin membranes. In view of the latter, it is surprising that mutant mice deficient in CAII (Car‐2n) have compact myelin. Since myelin basic protein also takes part in myelin compaction, we bred double CAII‐deficient, myelin‐deficient (MId) mutant mice, in which the adults would have some compact myelin sheaths and a partial deficiency in myelin basic protein, with a view to examining oligodendrocytes and myelin sheaths in the double mutant. Like the parent MId strain, the double mutants displayed tremors and seizures; however, the onset of seizures was delayed significantly in the double mutants, and the lifespan increased by several months. Like the brains of Car‐2n mutants, those of double mutants (MldCar‐2n) were deficient in mRNA and protein for CAII and showed upregulation of a different isozyme, CAIV. In the double mutants, oligodendrocytes were reduced in number, and the myelin sheaths and oligodendrocytes were swollen. The partial protection against seizures, which CAII deficiency conferred, suggests that acidosis in the central nervous system (CNS) of the Car‐2n and MldCar‐2n mice, due to absence of CAII from the choroid plexus, may downregulate the activity of NMDA receptors. The swelling of myelin and oligodendrocytes only in the MldCar‐2n suggests that CAIV activity is not sufficient for maintaining compact myelin when the myelin is partly deficient in myelin basic protein and severely deficient in CAII. The findings provide the first direct evidence for a role of carbonic anhydrase II in the compaction of myelin membranes. © 1995 Wiley‐Liss, Inc.
Regionally specific properties of midbrain glia: I. Interactions with midbrain neurons
Authors: Garcia‐Abreu J. , Neto Vivaldo Moura , Carvalho S. L. , Cavalcante L. A. 
Published: January 2005

AbstractRegional astrocyte cultures were obtained by dissecting and dissociating medial and lateral sectors of the midbrain from 14‐day Swiss mouse embryos. Once confluent, these cultures were tested by glial fibrillary acidic protein (GFAP) immunocytochemistry to confirm their astrocyte composition and for 2′‐3′ cyclic nucleotide 3′‐phosphohydrolase (CNPase) and microtubule‐associated protein 2 (MAP2) immunocytochemistry to rule out oligodendroglial and neuronal components, respectively. In confluent astrocyte cultures from either sector, virtually all cells were GFAP‐positive elements, most of which were flat cells accompanied by smaller numbers of flat cells with processes. Confluent astrocyte cultures, derived from medial (M) or lateral (L) sectors, were used as substrata for culturing dissociated cells from medial (m) or lateral (1) sectors of 14‐day embryonic midbrains. Fixed cocultures (LI, Lm, Mm, MI) were stained with an anti‐MAP2 antibody to verify neuronal aggregation and neuritic morphology. In spite of the morphological constancy of glia substrata at plating, MAP2‐positive cells in cocultures showed differences in the aggregation of somata and in the length, caliber, and branching of neurites. These differences, which depend mostly on the sector of origin of astrocytes, suggest that the substrata may differ in adhesiveness and/or growth‐promoting vs. growth‐interfering properties. Together with evidence for sectorial heterogeneity in brainstem radial glia, the present results raise the possibility that cultured astrocytes have properties that reflect the roles played by their parent radial glia in the developing brain. © 1995 Wiley‐Liss, Inc.