bluuebunny/crossref_metadata_2025_split huggingface dataset:
Different Routes of Ca2+ Influx in NMDA‐Mediated Generation of Nitric Oxide and Arachidonic Acid
Authors: Rodriguez‐Alvarez Jose , Lafon‐Cazal Mireille , Blanco Isaac , Bockaëert Joel 
Published: April 2006

AbstractNitric oxide and arachidonic acid act as inter‐ and intracellular messengers in the central nervous system. It is well known that the NMDA‐mediated generation of nitric oxide and arachidonic acid is dependent on extracellular Ca2+. However, the role of voltage‐dependent calcium channels (VDCCs) in this regard is poorly understood. We report here that NMDA‐mediated nitric oxide production in striatal neuron cultures is blocked (80%) by the L‐type VDCC antagonist nifedipine, but not by ω‐conotoxin or ω‐agatoxin IVA, antagonists of the N‐and P‐type VDCCs respectively. By contrast, none of the VDCC antagonists inhibited the NMDA‐mediated release of arachidonic acid. These data indicate that permeation through different Ca2+ channels is responsible for the production of arachidonic acid and nitric oxide in striatal neurons.
A Comparative Study of α2‐ and β‐Adrenoceptor Distribution in Pigeon and Chick Brain
Authors: Femández‐López Arsenio , Revilla Victoria , Candelas Maria Adoración , González‐Gil Joaquin , Diaz Alvaro , Pazos Angel 
Published: April 2006

AbstractThe pharmacological properties and anatomical distribution of α2, β1 and β2‐adrenoceptors in pigeon and chick brains were studied by both homogenate binding and tissue section autoradiography. [3H]Bromoxidine (α2‐adrenoceptor‐), [3H]CGP 12177 (β‐adrenoceptor) and [1251]cyanopindolol (β‐adrenoceptor) were used as radioligands. In both species, [3H]bromoxidine binding to avian brain tissue showed a pharmacological profile similar to that previously reported for α2‐adrenoceptors in mammals. Regarding the anatomical distribution, the areas with the highest densities of α2‐adrenoceptors in the pigeon brain included the hyperstriatum, nuclei septalis, tectum opticum and some brainstem nuclei. Most β‐adrenoceptors found in tissue membranes and sections from chick and pigeon brain were of the β2 subtype, in contrast to what has been reported in the mammalian brain, where the β1 subtype is predominant. A striking difference was found between the two species regarding the densities of these receptors: while pigeon brain was extremely rich in [1251]cyanopindolol binding throughout the brain (mainly cerebellum) in the pigeon, the levels of labelling in the chick brain were much lower; the exception was the cerebellum, which displayed a higher density than other parts of the brain in both species. Overall, our results support the proposed anatomical equivalences between a number of structures in the avian and mammalian encephalon.
Endothelins Promote the Activation of Astrocytes in Rat Neostriatum through ETB Receptors
Authors: Ishikawa Nobue , Takemura Motohide , Koyama Yutaka , Shigenaga Yoshio , Okada Toshikazu , Baba Akemichi 
Published: April 2006

AbstractThe effects of endothelin (ET)‐3 and an ETB receptor agonist on astrocytic activation in rat caudate putamen were examined by an immunohistochemical staining of glial fibrillary acidic protein (GFAP), a marker of reactive astrocytes. A single injection of 40 pmol ET‐3 into rat caudate putamen increased the number of GFAP positive cells compared to that in the contralateral saline‐injected side. Ala1,3,11,15‐ET‐1 (40 pmol), an ETB receptor agonist, also increased the number of striatal GFAP positive cells. The increases in GFAP positive cells were maximum (about 150% of the control side) in 1–2 weeks after injections of the ETs, and then reduced in 4 weeks. A continuous infusion of BQ788, an ETB receptor antagonist (23 nmol/day), into the lateral ventricle of the cerebrum antagonized the effect of Ala1,3,11,15‐ET‐1, while 80788 also reduced the number of GFAP positive cells in saline‐injected caudate putamen. Intrastriatal injection of 40 pmol Ala1,3,11,15‐ET‐1 did not affect the number of cells stained by B4 isolectin from Griffonia simplicifolia, which labels activated microglia/macrophages. Intraperitoneal administration of 5 mg/kg per day chloroquine and 0.2 mg/kg per day colchicine did not affect the action of Ala1,3,11,15‐ET‐1. These results suggest that activation of ETB receptors is involved in the induction of reactive astrocytes.
Excitatory Convergence of Y and Non‐Y Information Channels on Single Neurons in the PMLS Area, a Motion Area of the Cat Visual Cortex
Authors: Wang C. , Dreher B. , Huxlin K. R. , Burke W. 
Published: April 2006

AbstractWe analysed the receptive field properties of neurons in the posteromedial lateral suprasylvian (PMLS) visual cortical area of anaesthetized cats in which there was selective conduction block of the largest (Y‐type) fibres in one optic nerve. As in normal cats, in cats with selective block of one optic nerve the great majority of PMLS cells could be activated by photic stimulation through either eye. However, the responses evoked by stimulation via the eye with the selectively pressure‐blocked optic nerve (‘Y‐blocked eye’) were significantly weaker than those of the same cells evoked by the stimulation via the normal eye. Accordingly, eye dominance histograms were shifted markedly in favour of the normal eye. Furthermore, there was a significant shift towards lower preferred velocities when PMLS cells were photically stimulated via the Y‐blocked eye. Finally, when stimulated via the Y‐blocked eye, PMLS cells responded poorly or not at all to high stimulus velocities (≤100°/s). On the other hand, a number of receptive field properties, such as the spatial organization of receptive fields, the size of the discharge fields, orientation tuning and direction selectivity indices, were not significantly affected by the removal of the Y input. We conclude that virtually all neurons in the PMLS area of the cat receive excitatory input from both Y and non‐Y information channels, although the Y channel provides the dominant input and makes the principal contribution to the detection of high‐velocity motion.
Up‐regulation of Cyclooxygenase‐2 Expression in Cultured Microglia by Prostaglandin E2, Cyclic AMP and Non‐steroidal Anti‐inflammatory Drugs
Authors: Minghetti Luisa , Polazzi Elisabetta , Nicolini Alessia , Créminon Christophe , Levi Giulio 
Published: April 2006

AbstractCyclooxygenase‐2, the inducible isoform of cyclooxygenase, is highly expressed in microglial cells activated by bacterial lipopolysaccharide and is a major regulatory factor in the synthesis of prostanoids, such as prostaglandins, prostacyclin and thromboxanes. Since prostanoids are potent modulators of inflammation, immune responses and neurotoxicity, the regulation of their synthesis may be crucial for balancing microglial neuroprotective and neurotoxic activities. The present study shows that expression of cyclooxygenase–2 and prostanoid production in cultured rat microglia activated by lipopolysaccharide is up‐regulated by cyclic AMP (CAMP), as indicated by experiments performed in the presence of adenylyl cyclase activators, cAMP analogues and protein kinase A‐specific inhibitors. Exogenous prostaglandin E2 (PGE2), which elevates the cAMP level in microglial cells, also increased the lipopolysaccharide‐induced expression of cyclooxygenase–2 and production of thromboxane in a dose– and time‐dependent manner. The observations that the lipopolysaccharide‐induced prostanoid production was specifically increased by 11‐deoxy‐16,16‐dm PGE2, a selective agonist at the PGE2 receptor EP2 coupled to the activation of adenylyl cyclase, and that the enhancing effect of PGE2 was partially prevented by specific inhibitors of adenylyl cyclase and protein kinase A, suggest that the up‐regulation of cyclooxygenase–2 expression by PGE2 is mediated by CAMP, through a putative microglial EP2 receptor. Unexpectedly, non‐steroidal anti‐inflammatory drugs such as indomethacin and 6–methoxy naphthalene acetic acidic, which inhibit cyclooxygenase enzymatic activity and abrogate prostanoid synthesis, caused a moderate but consistent up‐regulation of cyclooxygenase–2 expression. In conclusion, while the strong up‐regulation of cyclooxygenase–2 expression by exogenous PGE2 appears to be mediated by EP2 receptors and CAMP, the limited down‐regulation caused by anti‐inflammatory drug treatments may be either due to arachidonic acid metabolites other than PGE2, or to PGE2 itself, acting through a distinct CAMP‐independent signalling pathway.
Selectivity of Macaque MT/V5 Neurons for Surface Orientation in Depth Specified by Motion
Authors: Xiao D.‐K. , Marcar V. L. , Raiguel S. E. , Orban G. A. 
Published: April 2006

AbstractArea MT/V5 in the macaque brain is one of the major cortical regions involved in the analysis of retinal image motion. The majority of the neurons in this cortical area have non‐uniform antagonistic surrounds as components of their receptive field complexes. Theoretical studies indicate that such asymmetrical surrounds should enable neurons to extract orientation in depth from motion. Here we show that nearly half of the MT/V5 neurons encode the tilt component of the orientation in depth of a plane specified by motion. Furthermore, we show that such selectivity for depth from motion depends on the presence of an asymmetrical surround and on the speed tuning of those asymmetrical surround influences.
Differential Expression of Syntrophins and Analysis of Alternatively Spliced Dystrophin Transcripts in the Mouse Brain
Authors: Górecki Dariusz C. , Lukasiuk Katarzyna , Barnard Eric A. , Abdulrazzak Hassan 
Published: April 2006

AbstractExpression of syntrophin genes, encoding members of the dystrophin‐associated protein complex, was studied in the mouse brain. In the hippocampal formation there is distinctive co‐localization of specific syntrophins with certain dystrophin isoforms in neurons, e.g. α1,‐syntrophin with the C‐dystrophin in CA regions and β2‐syntrophin with the G‐dystrophin in the dentate gyrus. Expression of the al‐syntrophin is predominant in CA regions and the olfactory bulb and it is also present in the cerebral cortex and the dentate gyrus. The β2‐syntrophin mRNA is most abundant in the dentate gyrus and is also evident in the pituitary, the cerebral cortex and in Ammon's horn and in traces in the caudate putamen. The choroid plexus was labelled by both α1 and β2‐syntrophin‐specific probes. The expression of syntrophins in the brain correlates with expression of dystrophins and dystroglycan. There are brain areas such as the cerebral cortex where several different syntrophins and dystrophins are expressed together. Syntrophin expression co‐localizes with utrophin in the choroid plexus and caudate putamen. Finally, no syntrophin was detected in the cerebellar Purkinje cells where the specific dystrophin isoform (P‐type) is present. This specific distribution of syntrophins in the brain is particularly interesting, as muscle syntrophin interacts with neuronal nitric oxide synthase. This may suggest that the dystrophin‐associated protein complex may be involved in synaptic organisation and signal transduction machinery in both muscle and neurons. The dystrophin isoform, with exons 71–74 spliced out and hence lacking syntrophin binding sites, had been believed to be predominant in the brain, but our analyses using in situ hybridization, S1 nuclease protection and the semi‐quantitative polymerase chain reaction revealed that this alternatively spliced mRNA is a minor, low abundance form in the brain.
Neurite Outgrowth Inhibitor of Gliotic Brain Tissue. Mode of Action and Cellular Localization, Studied with Specific Monoclonal Antibodies
Authors: Bovolental Paola , Fernaud‐Espinosa Isabel , Mendez‐Otero Rosalia , Nieto‐Sampedro Manuel 
Published: April 2006

AbstractMembranes from injured adult rat brain express a heparan/chondroitin sulphate proteoglycan that inhibits neurite outgrowth in vitro. We have developed monoclonal antibodies (Mabs) against this proteoglycan, two of which were characterized and used for the study of the inhibitor mode of action and localization in normal and injured adult brain. The antibodies recognized a molecule of apparent molecular weight 200 kDa in Western blots of injured brain membranes. One of the Mabs blocked both the inhibition of neurite outgrowth and the growth cone collapse activity, associated with the proteoglycan. In adult brain, inhibitor immunoreactivity was found predominantly in neurons but, after a lesion, it was associated mainly with reactive glial cells. The localization of neurite outgrowth inhibitors in reactive glia supports the idea that gliotic tissue is largely responsible for the failure of axonal regeneration in mammalian CNS
Synchronization of Neuronal Activity Promotes Survival of Individual Rat Neocortical Neurons in Early Development
Authors: Voigt Thomas , Baier Herwig , de Lima Ana Dolabela 
Published: April 2006

AbstractNeural activity is thought to play a significant role during the development of the cerebral cortex. In this study, we examined the effects of global activity block or enhancement and the effects of patterned firing on the ability of cultured rat neocortical neurons to survive during the second week in vitro, beyond the beginning of synaptogenesis. Blockade of neuronal activity by adding tetrodotoxin (TTX) and increasing magnesium concentration in the medium strongly reduced the survival of cortical cells. Increasing neuronal activity by raising the external potassium concentration significantly improved the survival of cortical neurons. We postulated that in a developing neuronal network the survival of nerve cells is regulated by synaptically mediated events that involve changes in the intracellular calcium concentration. To examine this question further, we monitored the activity of the developing network by optically recording the intracellular calcium signals of many neurons simultaneously. These recordings show that in low magnesium neocortical neurons express synchronized oscillation of their intracellular calcium concentration. The ability of a network to synchronize the changes in intracellular calcium of multiple cells appeared gradually during the second week in culture, paralleled by both an increase in the synaptic density and a decline in the number of surviving neurons. By examining the fate of identified cells several days after a recording session, we found that those nerve cells that were co‐activated with other neurons had a significantly higher chance to survive than cells that did not participate in synchronized events. These experiments demonstrate that during early cortical network development cortical neurons show synchronized firing activity and that the survival of neurons is at least partially dependent on this pattern of neuronal activity.
Selective Upregulation of Cytokine Receptor Subchain and Their Intracellular Signalling Molecules After Peripheral Nerve Injury
Authors: Yao Gui Lan , Kato Hidemasa , Khalil Mansur , Kiryu Sumiko , Kiyama Hiroshi 
Published: April 2006

AbstractNumerous studies have suggested that growth factors and cytokines play an important role in the survival of injured neurons and in neurite elongation. Therefore, intracellular signalling pathways activated by growth factors and cytokine receptors play an important role in neuronal survival or for the re‐establishment of connection. Since the JAK (janus kinase)‐STAT (signal transducers and activators of transcription) signal transduction pathway is known to play a major role in cytokine receptor signalling, we first examined regulation of JAK gene expression following peripheral nerve injury by in situ hybridization histochemistry. The rat hypoglossal nerve was axotomized unilaterally and the mRNA levels for JAKI, JAK2. JAK3 and TYK2 were examined in the hypoglossal nucleus at postoperative times ranging from 1 to 35 days. Among the JAK family members, JAK2 and JAK3 were substantially increased in injured hypoglossal motoneurons, whereas no significant increases were observed for JAK1 and TYK2. These changes were further confirmed by immunohistochemistry using antibodies specific to JAKP and JAK3. In addition, we examined the JAK2 and JAK3 associated cytokine receptor components, IL‐2R y and gp130, which are common to various cytokine receptors. Among these, gp130 immunostaining was upregulated after nerve injury. This was also confirmed by in situ hybridization. These results suggest that the injured neuron prepares the molecular machinery involved in certain cytokine receptor signalling pathways at an early phase of the regenerative process, accelerating for the neuron to respond to cytokines that may regulate survival and/or neurite elongation.
Reelin mRNA Expression During Mouse Brain Development
Authors: Schiffmann S. N. , Bernier B. , Goffinet A. M. 
Published: April 2006

AbstractUsing in situ hybridization, expression of the mRNA for reelin, the gene most probably responsible for the reeler trait, was studied during mouse brain development. from embryonic day 13 to maturity. The highest level of expression was found in Cajal‐Retzius neurons, while a high signal was also seen in the olfactory bulb, the external granular layer of the cerebellum and, particularly at early developmental stages, in hypothalamic differentiation fields, tectum and spinal cord. A moderate to low level of expression was found in the septa1 area, striatal fields, habenular nuclei, some thalamic nuclei, particularly the lateral geniculate, the retina and some nuclei of the reticular formation in the central field of the medulla. Paradoxically, no reelin expression was detected in radial glial cells, the cortical plate, Purkinje cells, inferior olivary neurons and many other areas that are characteristically abnormal in reeler mutant mice. Together with other preliminary studies, the present observations suggest that the action of reelin is indirect, possibly mediated by the extracellular matrix. Most of the data can be explained by supposing that reelin is a cell‐repulsive molecule which prevents migrating neurons from invading reelin‐rich areas, and thus facilitates the deployment of radial glial cell processes and the formation of early architectonic patterns.
Dopaminergic Neurons in the Rat Retina Express Dopamine D2/3 Receptors
Authors: Veruki Margaret L. 
Published: April 2006

AbstractThe localization of dopamine D2 and D3 receptors in the rat retina was studied using a polyclonal antibody raised against a peptide sequence common to the dopamine D2 and D3 receptors (D2/3). The D2/3 receptor antibody labelled a small number of somata in the innermost part of the inner nuclear layer and in the ganglion cell layer and a small number of photoreceptor outer segments. Processes in both plexiform layers were also labelled. Double‐labelling experiments with the antibody against the D2/3 receptor and an antibody against tyrosine hydroxylase to label dopaminergic neurons resulted in the co‐localization of the two antibodies. This demonstrates directly that dopaminergic neurons in the retina express D2/3 receptors. As previous biochemical and physiological studies have demonstrated that activation of D2–like receptors inhibits the release of dopamine in the retina, the present results suggest that the D2/3 receptors on dopaminergic neurons function as autoreceptors.
Cloning and Characterization of a Neural Cell Recognition Molecule on Axons of the Retinotectal System and Spinal Cord
Authors: Brümmendorf Thomas , Spaltmann Frank , Treubert Ullrich 
Published: April 2006

AbstractImmunoglobulin superfamily molecules in the brain are involved in distinct aspects of nervous system histogenesis, for example neuronal migration and axonal growth. To identify novel members of this superfamily in the chick nervous system, we developed a polymerase chain reaction‐based approach making use of sequence motifs of immunoglobulin‐like domains. In the present study, we report the molecular cloning of three isoforms, the biochemical analysis and the immunohistochemical characterization of one of the proteins identified in this screen. This molecule has 91% sequence identity with the limbic system‐associated membrane protein (LAMP) characterized in the rat and is therefore referred to as the chicken homologue of the latter (chLAMP). The molecule is a glycosylphosphatidyl‐inositol‐anchored 60 kDa protein with three immunoglobulin‐like domains and contains 40% N‐linked carbohydrate. We identify three different mRNA forms of chLAMP and show that two forms with distinct 5′‐termini are differentially transcribed in neural development. In addition, we demonstrate using a fusion protein expressed in eukaryotic cells that chLAMP has homophilic binding activity. The protein was found on a subset of axons in the central and peripheral nervous system and is likely to be involved in specific cell‐cell interactions in neurohistogenesis.
Increased Intermale Aggression and Neuroendocrine Response in Mice Deficient for the Neural Cell Adhesion Molecule (NCAM)
Authors: Stork O. , Welzl H. , Cremer H. , Schachner M. 
Published: April 2006

AbstractMice deficient for the neural cell adhesion molecule (NCAM) show morphological and behavioural abnormalities in the adult form, including a reduced size of the olfactory bulb, reduced exploratory behaviour, and deficits in spatial learning. Here we report increased aggressive behaviour of both homozygous (NCAM ‐/–) and heterozygous (NCAM +/–) male mutant mice towards an unfamiliar male intruding into their home cage. While plasma testosterone concentrations did not differ between genotypes before or after behavioural testing, corticosterone levels were higher in mutant residents than in wild‐type (NCAM +/+) residents 30 min after encountering the intruder. Levels of c‐fos mRNA, analysed to monitor neuronal activation, were similar in primary output structures of the olfactory bulb in NCAM‐deficient and NCAM +/+ mice, but were increased in brain areas of the limbic system in both NCAM –/– and NCAM +/– mutant mice after the behavioural test. These results indicate that abnormalities in social behaviour correlate with enhanced neuronal activity in limbic brain areas and result in increased social stress in NCAM‐deficient mice.
Effects of GDNF on Axotomized Sensory and Motor Neurons in Adult Rats
Authors: Munson John B. , McMahon Stephen B. 
Published: April 2006

AbstractGlial cell‐line‐derived neurotrophic factor (GDNF) is a potent neurotrophic factor shown to rescue developing and adult motoneurons in vitro and in vivo from programmed and injury‐induced cell death. To test whether GDNF would rescue adult mammalian sensory and motor neurons from physiological consequences of injury, the tibial nerve of rats was axotomized and, after a 10 day delay to permit injury processes to proceed, vehicle or GDNF was supplied directly to the nerve for 2 or 4 weeks or GDNF intrathecally for 2 weeks. Conduction velocity (CV) of both sensory and motor axons declined during the initial 10 days, and even more so if then treated with vehicle. Treatment with GDNF resulted in marginal improvement of sensory axon CV. CV of motor axons recovered significantly in a dose‐ and time‐dependent manner. The results suggest that GDNF may have therapeutic potential in the treatment of peripheral neuropathies.
GABAergic Transcallosal Neurons in Developing Rat Neocortex
Authors: Kimura Fumitaka , Baughman Robert W. 
Published: April 2006

AbstractIn the mature cerebral cortex the interhemispheric connections across the corpus callosum appear to be essentially completely excitatory on the basis of both immunocytochemical and electrophysiological studies. During late embryonic development, however, immunocytochemical staining reveals numerous GABA‐positive fibres in the callosum, which later largely disappear. The origin of these fibres and whether they represent functional GABAergic neurons has not been established. In the present study we used a combination of retrograde labelling in vivo with electrophysiology and immnunocytochemistry in cell culture to show that transiently at birth in rat pups a substantial number of transcallosal cortical cells are functional GABAergic neurons. Possible roles and fates for these neurons are discussed.