bluuebunny/crossref_metadata_2025_split huggingface dataset:
Functional Involvement of Sciatic Nerve‐derived Versicanand Decorin‐like Molecules and other Chondroitin Sulphate Proteoglycans in ECM‐mediated Cell Adhesion and Neurite Outgrowth
Authors: Braunewell Karl‐Heinz , Pesheva Penka , McCarthy James B. , Furcht Leo T. , Schmitz Brigitte , Schachner Melitta 
Published: April 2006

AbstractWe have previously described two proteoglycans from human sciatic nerve which are immunochemically related to the chondroitin sulphate proteoglycans versican and decorin. The chondroitin sulphate of the versican‐like molecule and the core protein of the decorin‐like molecule have been found previously to be up‐regulated after lesioning the adult mouse sciatic nerve. To investigate if the versican‐ and decorin‐like molecules are involved in cell‐extracellular matrix interactions, we studied the effect of both molecules on cell adhesion. The versican‐ and decorin‐like molecules, substrate‐coated in a mixture with fibronectin, but not with laminin or collagen types I or IV, inhibited the adhesion of several cell lines, neonatal dorsal root ganglion neurons and Schwann cells. The inhibitory activity was concentration‐dependent and mediated by the chondroitin sulphate. Furthermore, when different proteoglycans were incubated with fibronectin, only the versican‐ and decorin‐like molecules and the chondroitin sulphate proteoglycan aggrecan, but not the heparan sulphate proteoglycan perlecan, were able to inhibit fibronectin‐mediated cell adhesion. The versican‐ and decorin‐like molecules, substrate‐coated alone or in a mixture with fibronectin or laminin, were at most slightly inhibitory to neurite outgrowth from PC12 phaeochromocytoma cells and neonatal dorsal root ganglion neurons. In a solid‐phase ligand‐binding assay theversican‐ and decorin‐like molecules interacted with fibronectin, but not with laminin or collagen types I and IV. Binding of the versican‐like molecule to fibronectin and inhibition of cell adhesion by this molecule was mediated via the heparin and cell‐binding domains of fibronectin. These observations suggest that binding of the two proteoglycans to fibronectin is involved in the modulation of adhesion of cells to fibronectin.
Electrophysiological Characterization of a Novel Conotoxin That Blocks Molluscan Sodium Channels
Authors: Hasson Arik , Fainzilber Michael , Zlotkin Eliahu , Spira Micha 
Published: April 2006

AbstractA novel peptide toxin, PnIVB, isolated from the venom of Conus pennaceus blocks voltage‐gated sodium current in Aplysia neurons. Complete blockade is obtained at a PnIVB concentration of 80±2.2 nM and 50% blockade at 16±0.86 nM. The potency of PnIVB in blocking Aplysia sodium current is four orders of magnitude larger than that of tetrodotoxin. The toxin has no paralytic activity when injected into fish. The rapid blockade of sodium current by PnIVB is not associated with a change in the activation or inactivation kinetics of the current, or with the reversal potential. Sodium current blockade is reversible after a 30 min wash with 50 times the bath volume. The novel conotoxin PnlVB can be used as a powerful tool for mollusc neurobiological research and as a molecular probe to explore the structure‐function relations of voltage‐gated sodium channel subtypes.
Morphological Fate of Rhombomeres in Quail/Chick Chimeras: A Segmental Analysis of Hindbrain Nuclei
Authors: Marín Faustino , Puelles Luis 
Published: April 2006

AbstractQuail rhombomeres two to six (r2‐r6) were individually grafted homotopically into the hindbrain of chick embryos at 2 days of incubation. Nine to 10 days after the operation the chimeric embryos were fixed and processed for parallel cytoarchitectural and immunocytochemical study (with an anti‐quail antibody) in order to map the anatomical fate of the grafted tissue. Emphasis was placed on conventionally identified and distinct neuronal populations composing the sensory and motor longitudinal columns. Grafted rhombomeres consistently developed as complete transverse slices of the chimeric hindbrain. Interrhombomeric cell migration was either sparse or restricted to specific nuclei. The cranial nerve motor nuclei showed rhombomeric origins consistent with the patterns described in early embryos. Unexpectedly, alar r2 was found to form the auricular part of the cerebellum. As regards the cochlear nuclei, we found that nucleus angularis derives from r3 to r6, nucleus laminaris from r5 to r6, nucleus magnocellularis from r6 to r7 and nucleus olivaris superior from r5. The nuclei of the lateral lemniscus originated between r1 and r3. We also delimited the respective rhombomeric subdivisions of the sensory vestibular and trigeminal columns, both of which extend from r1 caudalwards throughout the hindbrain. There were consistently some interrhombomeric neuronal migrations inside the vestibular column, some motor nuclei and the reticular formation, involving only one rhombomere length. The pontine nuclei, which extended from r1 to r7, showed neuronal migrations that crossed several rhombomeres. On the whole, these results represent the first anatomical analysis of the mature avian hindbrain in terms of rhombomere‐derived domains.
Immunohistochemical Visualization of Brain‐derived Neurotrophic Factor in the Rat Brain
Authors: Dugich‐Djordjevic Millicent M. , Peterson Christine , Isono Fujio , Ohsawa Fukuichi , Widmer Hans R. , Denton Timothy L. , Bennett Gregory L. , Hefti Franz 
Published: April 2006

AbstractA purified polyclonal antibody preparation was made against recombinant human brain‐derived neurotrophic factor (BDNF) in guinea pig and characterized for use in immunoassays and immunohistochemistry. The anti‐BDNF antibodies specifically recognized BDNF in Western blots and immunoprecipitation. There was no cross‐reactivity with the other known mammalian members of the neurotrophin family, nerve growth factor, neurotrophin‐3 and neurotrophin‐4/5. In immunohistochemical analysis, the anti‐BDNF recognized exogenous BDNF injected into the brain of rats, whereas no signal was obtained with the other neurotrophins. Preabsorption with native BDNF abolished the immunoreactivity in brain sections. These studies identify the anti‐BDNF as a tool for immunocytochemistry and the development of an immunoassay. Immunohistochemical analysis revealed widespread neuronal localization of BDNF in many brain areas. BDNF was localized in all subpopulations of hippocampal neurons. The distribution in the hippocampus suggests localization in the cytoplasm of cell bodies and dendrites.
Early Changes in Prodynorphin mRNA and ir‐Dynorphin A Levels after Kindled Seizures in the Rat
Authors: Romualdi P. , Donatini A. , Bregola G. , Bianchi C. , Beani L. , Ferri S. , Simonato M. 
Published: April 2006

AbstractProdynorphin mRNA and immunoreactive dynorphin A (ir‐dynorphin A) levels were measured in different brain areas at various time points after amygdala kindled seizures. In the hippocampus, striatum and hypothalamus, prodynorphin mRNA levels were not significantly changed in kindled rats (killed 1 week after the last stimulus‐evoked seizure), but they were significantly increased 1 h after seizures. The relative increase was the highest in the hippocampus (∼3‐fold). In the brainstem, midbrain and cerebral cortex no changes in prodynorphin mRNA were detected in kindled rats, 1 h or 1 week after a kindled seizure. ir‐Dynorphin A levels were significantly reduced in the hippocampus and in the striatum of kindled rats, as well as 5 and 60 min after kindled seizures, but they were increased back to control levels after 120 min. In the hypothalamus, ir‐dynorphin A levels were significantly increased 120 min after a kindled seizure. ir‐Dynorphin A levels were also significantly reduced in the brainstem and in the frontal, parietal and temporal cortex 120 min, but not 5 or 60 min, after a kindled seizure. Taken together, these data support the hypothesis that the dynorphinergic system is activated after amygdala kindled seizures, with different kinetics in different brain areas.
Glial Cells in the Mouse Hippocampus Express AMPA Receptors with an Intermediate Ca2+ Permeability
Authors: Seifert Gerald , Steinhäuser Christian 
Published: April 2006

AbstractRecently, we could demonstrate that ‘complex’ glial cells in mouse hippocampal slices express glutamate receptor channels of the α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid (AMPA)/kainate subtypes. In the present study, we further characterized this glial receptor. Since voltage‐clamp control is imperfect and diffusion barriers hinder the quantitative analysis of the receptor currents in situ, the patch‐clamp technique was applied to glial cells acutely isolated from the mouse hippocampal CA1 stratum radiatum subregion. A concentration‐clamp technique was used which enabled very fast exchange of the extracellular solutions. Thus, it was possible to characterize the transient receptor currents with high time resolution. Application of L‐glutamate, AMPA and L‐homocysteate induced rapidly activating and fast desensitizing receptor currents in the suspended glial cells. In contrast, kainate induced non‐desensitizing currents. The corresponding dose‐response curve revealed a half‐maximum of current activation at 350 μM. The current/voltage relationship of the kainate‐evoked response was linear, with a reversal potential at ∼9 mV. Analysis of the reversal potential in solutions containing high concentrations of CaCl2 confirmed earlier in situ data by demonstrating significant Ca2+ permeability of the glial glutamate receptor channels in the hippocampus. The kainate‐induced receptor currents were markedly increased by cyclothiazide, a substance which selectively potentiates glutamate receptors of the AMPA subtype. We conclude that glial cells of the juvenile hippocampus mainly express heteromeric high‐affinity AMPA receptors. Most probably, the receptor channels are assembled from the low Ca2+‐permeable glutamate receptor‐2 subunit together with Ca2+‐permeable AMPA‐preferring subunits.
Activation of Class II or III Metabotropic Glutamate Receptors Protects Cultured Cortical Neurons Against Excitotoxic Degeneration
Authors: Bruno V. , Battaglia G. , Copani A. , Giffard R. G. , Raciti G. , Raffaele R. , Shinozaki H. , Nicoletti F. 
Published: April 2006

AbstractTrans‐1‐aminocyclopentane‐1,3‐dicarboxylic acid, a mixed agonist of all metabotropic glutamate receptor (mGluR) subtypes, is known to produce either neurotoxic or neuroprotective effects. We have therefore hypothesized that individual mGluR subtypes differentially affect neurodegenerative processes. Selective agonists of subtypes which belong to mGluR class II or III, such as (2s, 1′R,2′R,3′R)‐2‐(2,3‐dicarboxycyclopropyl)‐glycine (DCG‐IV) (specific for subtypes mGluR2 or 3) or L‐2‐amino‐4‐phosphonobutanoate and L‐serine‐O‐phosphate (specific for subtypes mGluR4, 6 or 7), were highly potent and efficacious in protecting cultured cortical neurons against toxicity induced by either a transient exposure to N‐methyl‐D‐aspartate (NMDA) or a prolonged exposure to kainate. In contrast, agonists that preferentially activate class I mGluR subtypes (mGluR1 or 5), such as quisqualate or trans‐azetidine‐2,3‐dicarboxylic acid, were inactive. DCG‐IV was still neuroprotective when applied to cultures after the toxic pulse with NMDA. This delayed rescue effect was associated with a reduction in the release of endogenous glutamate, a process that contributes to the maturation of neuronal damage. We conclude that agonists of class II or III mGluRs are of potential interest in the experimental therapy of acute or chronic neurodegenerative disorders.
Optical Imaging of the Layout of Functional Domains in Area 17 and Across the Area 17/18 Border in Cat Visual Cortex
Authors: Bonhoeffer Tobias , Kim Dae‐Shik , Malonek Dov , Shoham Doron , Grinvald Amiram 
Published: April 2006

AbstractOptical imaging based on intrinsic signals was used to investigate the functional architecture of cat area 17 and the border between areas 17 and 18. The visual stimuli were gratings of different spatial frequencies moving at different angles, in different directions and with different speeds. In area 17 the iso‐orientation domains were usually organized in patches rather than as elongated bands. Patches with different orientation preferences were arranged radially forming ‘pinwheels’ around ‘orientation centres’. The pinwheel density was ∼1.7‐fold higher than in area 18. To explore clustering according to direction of motion, stimuli having the same orientation but moving in opposite directions were used. These two stimuli yielded very similar activity maps giving no indication of robust directionality clustering. Using near infrared light we were able to simultaneously image ocular‐dominance and iso‐orientation domains. A quantitative assessment of the relative strengths of the two subsystems showed that in upper cortical layers clustering according to orientation preference was three‐fold stronger than clustering according to ocular dominance. The functional organization of spatial frequency was also examined. When we compared the activated regions by stimuli having different spatial frequency and moving at different velocities we observed that neurons were clustered also in these respects. We also investigated the functional architecture at the area 17/18 border and found that orientation maps at both sides of the border were not independent of each other. The map of area 17 smoothly blended into that of area 18. Similarly, the preferred spatial frequency of the neurons changed gradually over a distance of ∼0.8 mm at the region of the area 17/18 border.
Alternative RNA Splicing Generates Diversity of Neuropeptide Expression in the Brain of the Snail Lymnaea: In Situ Analysis of Mutually Exclusive Transcripts of the FMRF amide Gene
Authors: Santama Niovi , Benjamin Paul R. , Burke Julian F. 
Published: April 2006

AbstractIn the CNS of the snail Lymnaea stagnalis, Phe‐Met‐Arg‐Phe‐amide (FMRFamide)‐like and additional novel neuropeptides are encoded by a common, multi‐exon gene. This complex locus, comprising at least five exons, is subject to post‐transcriptional regulation at the level of alternative RNA splicing. Our aim was first to analyse the pattern by which exons of this neuropeptide locus combine during splicing of the primary RNA transcript, and second to investigate the functional significance of splicing by mapping the expression and neuronal localization in the CNS of the alternative mRNA transcripts, in the context of defined neuronal networks and single identified neurons. The approach was a combination of comparative in situ hybridization and immunocytochemistry, using a battery of exon‐specific oligonucleotides and anti‐peptide antisera. The analysis illustrated that exons III, IV and V were always coexpressed and colocalized whereas the expression of exon II was always differential and mutually exclusive. Both sets of exons were, however, coexpressed with exon I: the total number of exon I‐expressing neurons was equal to the combined number of neurons expressing exon III/IVA/ and neurons expressing exon II. In addition, it was revealed that the extreme 5’of exon II, encoding a potential hydrophobic leader signal, was not expressed in the CNS of Lymnaea but was apparently spliced out during RNA processing. Both mRNA transcripts of the FMRFamide locus, type I (exons I/II) and type 2 (exons I/III/IV/V), were translated in the CNS and the resulting protein precursors were also expressed in a mutually exclusive fashion, as were their respective transcripts. The expression of alternative transcripts within identified networks or neuronal clusters was heterogeneous, as exemplified by the cardiorespiratory network. On the basis of this work and a previous cDNA analysis, we put forward a revised model of differential splicing and expression of the FMRFamide gene in the CNS of Lymnaea.
Fibroblast Growth Factors and Insulin Growth Factors Combine to Promote Survival of Rat Schwann Cell Precursors Without Induction of DNA Synthesis
Authors: Gavrilovic Jelena , Brennan Angela , Mirsky Rhona , Jessen Kristjan R. 
Published: April 2006

AbstractIn embryonic rat nerves, we recently identified an early cell in the Schwann cell lineage, the Schwann cell precursor. We found that when these cells were removed from contact with axons they underwent rapid apoptotic death, and that in a proportion of the cells this death could be prevented by basic fibroblast growth factor (bFGF, FGF‐2). We now report that 100% of Schwann cell precursors isolated from peripheral nerves of 14‐day‐old‐rat embryos can be rescued by a combination of insulin‐like growth factor (IGF) 1 or 2 in combination with either acidic FGF (aFGF, FGF‐1), bFGF or Kaposi's sarcoma FGF (K‐FGF; FGF‐4). The precursors display an absolute requirement for both an IGF and an FGF to achieve maximal survival. Elevation of intracellular levels of cAMP by forskolin does not result in a significant shift in the IGF/FGF dose‐response curves. In contrast, the percentage of precursors rescued by FGF in the presence of insulin is dramatically increased by elevation of cAMP. These growth factor combinations did not stimulate DNA synthesis significantly in Schwann cell precursors. These findings show that cooperation between growth factors is required to suppress cell death in Schwann cell precursors, and suggest that survival and DNA synthesis are regulated by distinct growth factor combinations in these cells. The observations are consistent with the idea that survival regulation by FGFs and IGFs plays an important role in the development of glial cells in early embryonic nerves.
Distinct Populations of Identified Glial Cells in the Developing Rat Spinal Cord Slice: Ion Channel Properties and Cell Morphology
Authors: Chvátal Alexandr , Pastor Andrea , Mauch Marianne , Syková Eva , Kettenmann Helmut 
Published: April 2006

AbstractFour types of glial cells could be distinguished in the grey matter of rat spinal cord slices at postnatal days 1‐19 (P1‐P19), based on their pattern of membrane currents as revealed by the whole cell patch clamp technique, and by their morphological and immunocytochemical features. The recorded cells were labelled with Lucifer Yellow, which allowed the subsequent identification of cells using cell‐type‐specific markers. Astrocytes were identified by positive staining for glial fibrillary acidic protein (GFAP). These were morphologically characterized by multiple, very fine and short processes and electrophysiologically by symmetrical, non‐decaying K+ selective currents. Oligodendrocytes were identified by a typical oligodendrocyte‐like morphology, lack of GFAP staining and positive labelling with a combination of O1 and O4 antibodies (markers of the oligodendrocyte lineage), and their membrane was dominated by symmetrical, passive, decaying K+ currents. The third population of glial cells was also characterized by positive staining for O1/O4 or only for O4 antigens, lack of GFAP staining and, in some cells, oligodendrocyte‐like morphology. However, these cells could be distinguished by the presence of inwardly rectifying (KDR), delayed outwardly rectifying (KDR) and A‐type K+ currents (KA), representing the most likely glial precursor cells of the oligodendrocyte lineage. The fourth population of glial cells had small somata and a widespread network of long processes with no apparent orientation preference. In one case, processes were positively labelled with GFAP, while 30% were characterized by faint, diffuse staining. These cells expressed a complex pattern of voltage‐gated channels, namely Na+, KDR, KA and KIR channels. In contrast to neurons, the amplitude of Na+ currents was at least one order of magnitude smaller than the K+ currents, and none of these cells showed the ability to generate action potentials in the current clamp mode. Since none of these cells could be labelled by oligodendrocyte markers we assume that they were either astrocytes or glial precursor cells of the astrocyte lineage. The four cell types were found in all regions of the grey matter. When randomly accessing the glial cells, the probability of recording from the oligodendrocyte precursor cells and the glial cells with Na+ currents decreased during development. At P1‐P3, 50% of the cells revealed the Na+ current, while at P13‐P15 only 18% did. Concomitantly, the number of glial cells with astrocyte‐ and oligodendrocyte‐like membrane currents increased from 19 and 12% to 41 and 35.5% respectively. We conclude that the glial cells in the spinal cord slices possess distinct morphological, immunohistochemical and physiological properties, and that the glial populations undergo changes during postnatal development.
Glutamate Induces c‐fos Proto‐oncogene Expression and Inhibits Proliferation in Oligodendrocyte Progenitors: Receptor Characterization
Authors: Liu Hsueh‐Ning , Almazan Guillermina 
Published: April 2006

AbstractThe effect of glutamate on c‐fos expression in oligodendrocyte progenitors was investigated by Northern blot analysis. Glutamate caused rapid and transient induction. Both 6‐cyano‐7‐nitro‐quinoxaline‐2,3‐dione (CNQX) and 6,7‐dinitroquinoxaline‐2,3‐dione (DNQX), two competitive non‐NMDA ionotropic receptor antagonists, reduced glutamate‐induced c‐fos expression, whereas the NMDA antagonist MK‐801 was ineffective. In addition, the glutamate receptor agonists (±)‐α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionic acid hydrobromide (AMPA) and kainate strongly induced c‐fos. However, the metabotropic receptor agonist trans‐(±)‐1‐amino‐(1S,3R)‐cyclopentanedicarboxylic acid (trans‐(±)‐ACPD) did not increase c‐fos mRNA level and the antagonist L‐(+)‐2‐amino‐3‐phosphonopropionic acid did not block glutamate‐induced c‐fos mRNA. These findings indicate that c‐fos induction in oligodendrocyte progenitors is mediated through the AMPA/kainate receptors, while NMDA and metabotropic receptor subtypes are not involved. Chelation of extracellular calcium by EDTA prevented glutamate‐induced c‐fos expression. Similarly, the protein kinase C inhibitor 1‐(5‐isoquinoline‐sulphonyl)‐2‐methylpiperazine dihydrochloride (H7) and down‐regulation of protein kinase C by prolonged exposure to phorbol‐12‐myristate 13‐acetate blocked c‐fos induction. These results suggest that induction of c‐fos through AMPA/kainate receptors is dependent on extracellular calcium influx and involves downstream activation of phorbol ester‐sensitive protein kinase C. The effect of glutamate on oligodendrocyte progenitor proliferation was assessed by [3H]thymidine incorporation. Glutamate and the agonists kainate and AMPA, but not trans‐(±)‐ACPD, caused a dose‐dependent decrease in [3H]thymidine incorporation. All these pharmacological agents were not toxic to oligodendrocyte progenitors. CNQX reversed the inhibitory effects produced by glutamate and the various agonists. These results suggest that glutamate may modulate the growth and differentiation of oligodendrocytes in the central nervous system.