bluuebunny/crossref_metadata_2025_split huggingface dataset:
Taurine Release Evoked by NMDA Receptor Activation is Largely Dependent on Calcium Mobilization from Intracellular Stores
Authors: Menéndez N. , Solis J. M. , Herreras O. , Galarreta M. , Conejero C. , del Río R. Martin 
Published: April 2006

AbstractIt is known that the activation of N‐methyl‐d‐aspartate (NMDA) receptors leads to an increase in extracellular taurine concentration in different brain regions. The mechanism that mediates this effect is not totally understood. In this study, rat hippocampal slices were used to determine the dependence of NMDA‐induced taurine release on extracellular calcium and/or on calcium mobilization from intracellular stores. NMDA was administered through a microdialysis probe inserted into the slice, at the level of CA1 stratum radiatum, which was also used to collect amino acids from the extracellular space. Field potentials evoked by stimulation of the Schaffer collaterals and recorded in the stratum pyramidale of CA1 were used as a control of NMDA receptor activation. NMDA induced a marked increase in extracellular taurine levels and a decrease in field potential amplitude, and both effects were suppressed in the presence of MK‐801, a blocker of the NMDA receptor‐linked channel. Dantrolene, an inhibitor of calcium release from intracellular stores, partially inhibited the extracellular taurine increase, while 2‐nitro‐4‐carboxyphenyl‐N,N‐diphenyl carbamate (NCDC), an inhibitor of phosphatidylinositol‐specific phospholipase C activation, had no effect. Removal of extracellular calcium diminished, but did not abolish, the extracellular taurine increase caused by NMDA. The remaining taurine response was totally suppressed by dantrolene, and also by NCDC. These results demonstrate that the release of taurine induced by NMDA receptor activation is triggered by the increase in cytoplasmic calcium concentration. We suggest that, under physiological conditions, calcium influx provides the signal for NMDA‐induced taurine release, which is amplified by calcium‐dependent calcium mobilization from intracellular stores. In the absence of extracellular calcium, NMDA is still able to evoke taurine release through a mechanism that implies calcium release from inositol 1,4,5‐trisphosphate‐sensitive stores.
Adenoviral Vector as a Gene Delivery System into Cultured Rat Neuronal and Glial Cells
Authors: Caillaud Catherine , Akli Said , Vigne Emmanuelle , Koulakoff Annette , Perricaudet Michel , Poenaru Livia , Kahn Axel , Berwald‐Netter Yoheved 
Published: April 2006

AbstractPrevious studies have demonstrated that a defective recombinant adenovirus can infect a wide range of postmitotic and slowly proliferating cell types such as hepatocytes, myotubes, pneumocytes and intestinal cells (Stratford‐Perricaudet et al., Hum. Gene Ther., 1, 241–256, 1990; Quantin et al., Proc. Natl. Acad. Sci. USA, 89, 2581–2584, 1992; Jaffe et al., Nature Genetics, 1, 372–378, 1992). We have used a defective recombinant adenovirus, Ad.RSVβgal, containing the Escherichia coliβ‐galactosidase gene targeted to the nucleus under the transcriptional control of the Rous sarcoma virus long terminal repeat promoter (Stratford‐Perricaudet et al., J. Clin. Invest., 90, 626–630, 1992) to infect non‐dividing neural cells in primary culture. We show that 80–100% of neuronal and astroglial cells infected with a viral titre lower than 109 p.f.u./ml express β‐galactosidase for at least 1 month without cell damage. These results demonstrate the potential usefulness of recombinant adenovirus infection for the analysis of brain‐specific gene regulation and for the transfer of genes into neural cells before their transplantation into the brain.
Increased Expression of GAP‐43, Somatostatin and Neuropeptide Y mRNA in the Hippocampus During Development of Hippocampal Kindling in Rats
Authors: Bendotti C. , Vezzani A. , Tarizzo G. , Samanin R. 
Published: April 2006

AbstractThe expression and distribution of the mRNA coding for the growth‐associated protein‐43 (GAP‐43), a putative marker for neuritic growth, for preprosomatostatin and the preproneuropeptide Y (ppNPY) were analysed in the rat hippocampus during the development of hippocampal kindling by an in situ hybridization technique and computer‐assisted grain counting in the cell. The levels of GAP‐43 mRNA increased significantly in the CA3 pyramidal neurons and hilar polymorphic neurons of the dentate gyrus 2 days after stage 2 of kindling (preconvulsive stage) but not stage 5 (full seizure expression) in the stimulated hippocampus. The distribution of GAP‐43 mRNA was the same in the hippocampus of kindled rats as in sham‐stimulated animals. Preprosomatostatin mRNA and ppNPY mRNA contents rose significantly in the hilar polymorphic neurons of the dentate gyrus of the stimulated and contralateral hippocampus at both stages of kindling, with the greatest effect at stage 5. In addition, the number of ppNPY mRNA neurons in the fascia dentata was significantly higher in kindled rats than in controls, but there were no differences in the number of preprosomatostatin mRNA‐positive cells. Preprosomatostatin and ppNPY mRNAs were also increased in the neurons of the stratum oriens of the CA1 ‐ CA3 subfield of fully kindled animals, whereas at stage 2 only neurons of the CA1 stratum oriens showed a significant increase of preprosomatostatin mRNA. No changes in preprosomatostatin and ppNPY mRNA expression were observed in the various regions of the hippocampus after a single afterdischarge or 1 month after stage 5. These data show that synthesis of somatostatin and neuropeptide Y increases in certain neurons of the hippocampus during the development of hippocampal kindling, and support the suggestion that these peptides are involved in epileptogenesis. Moreover, the increased synthesis of GAP‐43 may contribute to the synaptic remodelling of certain hippocampal neurons during kindling.
GAP‐43, aFGF, CCK and α‐ and β‐CGRP in Rat Spinal Motoneurons Subjected to Axotomy and/or Dorsal Root Severance
Authors: Piehl F. , Arvidsson U. , Johnson H. , Cullheim S. , Dagerlind Å. , Ulfhake B. , Cao Y. , Elde R. , Pettersson R. F. , Terenius L. , Hökfelt T. 
Published: April 2006

AbstractThe mRNA levels for growth‐associated protein 43 (GAP‐43), acidic fibroblast growth factor (aFGF), α and β‐calcitonin gene‐related peptide (CGRP), cholecystokinin (CCK) and choline acetyltransferase (ChAT) in rat lumbar spinal motoneurons were studied by in situ hybridization 1, 5 and 21 days and 20 weeks following unilateral peripheral nerve sectioning, ventral rhizotomy or dorsal rhizotomy. Furthermore, CGRP‐ and aFGF‐like immunoreactivities in the ventral horn were studied using immunohistochemistry. One to 21 days after axotomy, GAP‐43 and α‐CGRP mRNAs increased in lesioned motoneurons, while the aFGF mRNA levels were marginally higher in motoneurons on the lesion side as compared to the control side. β‐CGRP, CCK and ChAT mRNA levels, on the other hand, decreased during the short‐term response (1 – 21 days) to axotomy. After ventral rhizotomy, but not peripheral axotomy, there was complete disappearance of aFGF‐like immunoreactivity in the ventral root proximal to the lesion. In animals subjected to long‐term survival (20 weeks) after peripheral axotomy, the expression of all studied substances had returned to normal levels. Unilateral dorsal rhizotomy did not induce any substantial short‐ or long‐term shifts in the cellular expression of the GAP‐43, aFGF, CGRP and CCK peptides or their mRNAs in motoneurons of lesioned segments. These results indicate that peptides/proteins in motoneurons are expressed differentially after axotomy. Whereas α‐CGRP and GAP‐43 are up‐regulated, CCK and β‐CGRP become down‐regulated and aFGF is largely unaffected.
Alterations of G‐protein Coupling Function in Phosphoinositide Signalling Pathways of Rat Hippocampus by Ischaemic Brain Injury
Authors: Lu You M. , Lu Bu F. , Yan Yu L. , Yan Tin H. , Ho Xiaon P. , Wang Wen J. 
Published: April 2006

AbstractThe activation of membrane‐associated phospholipase C is rapidly and transiently induced in the central nervous system by a variety of stimuli. Ischaemic brain injury is one of the situations that leads to a dramatic increase in polyphosphoinositide (PPI) turnover. In this study, stimulation of PPI hydrolysis by glutamate (500 μM) was measured in hippocampal slices from rats up to 21 days after an ischaemic insult of 30 min. Ischaemia was induced using the four‐vessel occlusion method. PPI hydrolysis elicited by glutamate was significantly increased in the slices prepared from ischaemic rats 24 h after reperfusion, the accumulation of inositol phosphates (InsPs) and inositol 1,4,5‐trisphosphate (InsP3) was 614±74% (n= 8) and 182±11% (n= 9) of the basal level respectively. This potentiation was also observed 21 days after ischaemia. Hyper‐responsiveness to glutamate was also accompanied by an increase in AIF−4‐stimulated formation of [3H]inositol phosphates. In addition, global ischaemia did not change either high‐affinity [3H]glutamate binding in hippocampal membranes or the stimulation of PPI hydrolysis by carbachol or noradrenaline in hippocampal slices. The present results suggest that the increased responsiveness to glutamate is the result, at least in part, of functional changes at the G‐protein level, and may contribute to the pathophysiology of ischaemic brain injury or to the regenerative phenomena that accompany ischaemic damage.
The Contribution of Intracortical Connections to Horizontal Spread of Activity in the Neocortex as Revealed by Voltage Sensitive Dyes and a Fast Optical Recording Method
Authors: Albowitz B. , Kuhnt U. 
Published: April 2006

AbstractCoronal slices from guinea‐pig visual neocortex were stained with voltage‐sensitive fluorescence dyes RH414 or RH795. Activity was evoked by electrical stimulation of either the white matter or layer I. Emitted light intensity changes representing summated changes of membrane potential were recorded by a 10 × 10 photodiode array with a temporal resolution of 0.4 ms and a spatial resolution of 94 μm. The distribution and spread of activity in the horizontal direction was analysed. Following stimulation of the white matter or layer I, two regions of activity were differentiated in the medio‐lateral direction: a central region (∼1 mm wide) of high‐amplitude activity close to the stimulation electrode and, distant from the stimulation electrode, peripheral regions of low‐amplitude activity. Central and peripheral regions differed in their rates of decline, their relative extent with stimulation of different sites and within different layers. The total extent of non‐synaptic evoked activity did not exceed that of the central region of high‐amplitude activity. Along the extent of non‐synaptic activity, onset latencies of potentials were almost constant. Thus, activity of high amplitude in the central region was likely mediated by simultaneous activation of distributed afferent fibres. In contrast, no non‐synaptic activity was found in peripheral regions. Therefore it is suggested that this low‐amplitude activity was mediated without direct afferent activation but via long‐distance intracortical horizontal pathways. These pathways are known to terminate in layer III, and accordingly latencies of responses in the periphery were shortest in upper cortical layers, whereas in the central region, latencies increased from lower to upper cortical layers.
Excitatory Drive from Deep Cerebellar Neurons to the Superior Colliculus in the Rat: an Electrophysiological Mapping Study
Authors: Max Westby G. W. , Collinson Christine , Dean Paul 
Published: April 2006

AbstractThe cerebello‐tectal projection arising from the interpositus nucleus was investigated electrophysiologically to test the hypothesis that the deep cerebellar nuclei constitute a source of tonic excitation in the superior colliculus. A total of 117 spontaneously active collicular neurons were recorded during GABA microinjection into 26 interpositus sites, where tonic single‐cell deep cerebellar activity was also simultaneously recorded. GABA injection always led to suppression of interpositus activity, while in the colliculus a clear pattern of results emerged. 58% of superior colliculus cells showed no response to suppression of interpositus activity, 35% showed a frequency decrease and 7% showed a frequency increase. The majority of these responsive cells were found in a laterally located sheet of cells mainly restricted to the intermediate white layer, in close register with the known cells of origin of the predorsal bundle and completely overlapping the terminals of the nigrotectal pathway originating in dorsolateral substantia nigra pars reticulata. The implications of these results for cooperative theories of head movement control involving the superior colliculus, cerebellum and precerebellar nuclei are discussed.
Development of Calbindin‐D28k Immunoreactive Neurons in the Embryonic Chick Lumbosacral Spinal Cord
Authors: Antal Miklós , Polgár Erika 
Published: April 2006

AbstractThe development of immunoreactivity for the calcium‐binding protein calbindin‐D28k (CaB) was investigated in the embryonic and hatched chick lumbosacral spinal cord. CaB‐immunoreactive neurons were revealed in the dorsal and ventral horns as well as in the intermediate grey matter from early stages of neuronal development. CaB immunoreactivity was first detected in large neurons in the presumptive dorsal horn at embyronic day 5, while small neurons in the lateral dorsal horn were the last to appear, at embryonic day 10. We have identified and traced the morphological maturation of six CaB‐immunoreactive cell groups, three in the dorsal horn and three in the ventral horn. In the dorsal horn these groups were (1) large neurons in the lateral dorsal horn (laminae I and IV), (2) small neurons in the lateral dorsal horn (lamina II), and (3) small neurons in the medial dorsal horn (lamina III). All three groups were present throughout the entire length of the lumbosacral spinal cord and showed persistent CaB immunoreactivity. In the ventral horn, CaB‐immunoreactive neurons were classified into the following three categories: (1) Neurons dorsal to the lateral motor column (lamina VII). These neurons were present exclusively in the upper lumbosacral segments (LS1 – 3), and they showed steady CaB immunoreactivity during their maturation. (2) Neurons at the dorsomedial aspect of the lateral motor column (at the border of laminae VII and IX). This population of neurons was characteristic of the lower segments of the lumbosacral cord (LS5 – 7) and presented transient CaB expression. (3) Neurons within the lateral motor column (lamina IX). These neurons were dispersed throughout the length of the lumbosacral spinal cord. They were three to four times more numerous in the upper than in the lower lumbosacral segments, and their numbers declined throughout LS1 – 7 as the animal matured. The characteristic features of the development of neurons immunoreactive for CaB are discussed and correlated with previous neuroanatomical and physiological studies concerning sensory and motor functions of the developing chick spinal cord.
βAPP Gene Expression is Increased in the Rat Brain After Motor Neuron Axotomy
Authors: Solà Carme , García‐Ladona F. Javier , Sarasa Manuel , Mengod Guadalupe , Probst Alphonse , Palacios Gabriel , Palacios José M. 
Published: April 2006

AbstractThe response of the βAPP gene to neuronal injury was studied in the facial and hypoglossal nerve nuclei of the rat after corresponding nerve axotomy. Increased levels of βAPP 695, 714, 751 and 770 mRNAs were observed after either facial or hypoglossal nerve axotomy in the parent ipsilateral motor neurons. The increase was gradual, with maximal values 7 days after axotomy. βAPP mRNA expression returned to normal values 60 days after the lesion. Increased βAPP immunostaining was also detected in ipsilateral chromatolytic motor neurons. No change in βAPP immunoreactivity was observed in oligodendrocytes, another cell type expressing βAPP under normal conditions. A rapid increase in the expression of the GFAP gene was observed in reactive astrocytes surrounding chromatolytic neurons in the ipsilateral facial or hypoglossal nuclei. Thus, in contrast with other models of neuronal injury, where only the Kunitz protease inhibitor‐containing βAPP mRNA isoforms are increased, all βAPP mRNAs are increased in the axotomy model. Furthermore, although βAPP expression has been shown to be increased in reactive astrocytes following neuronal injury, in the present study the increase was essentially found in the motor neurons reacting to axotomy.
Embryonic Optic Nerve Tissue Fails to Support Neurite Outgrowth by Central and Peripheral Neurons In Vitro
Authors: Shewan Derryck , Berry Martin , Bedi Kuldip , Cohen James 
Published: April 2006

AbstractThe failure of axon regeneration in the injured mammalian central nervous system has been ascribed, in part, to the inhibitory effects of myelin proteins. To investigate the influence of myelination on neurite growth and regeneration by both central nervous system and peripheral nervous system neurons, isolated rat neonatal retinal ganglion cells and adult and neonatal dorsal root ganglion neurons were cultured on cryostat sections of both immature unmyelinated and mature fully myelinated adult rat optic nerve. In agreement with earlier studies using neonatal peripheral neurons, the adult optic nerve failed to support neurite outgrowth from any of the neurons tested. A new finding was that tissue sections from unmyelinated optic nerve (aged embryonic days 18 and 20, and postnatal days 1–3), also failed to support the growth of neurites from neonatal retinal ganglion cells and both neonatal and adult dorsal root ganglion neurons. Neonatal retinal ganglion cells also failed to extend neurites on sections of pre‐degenerated sciatic nerve, a tissue shown in our previous work to be a good substratum for supporting neurite growth for both neonatal and adult DRG neurons. These results suggest that cells in the immature optic nerve either express widely acting axon growth inhibitory molecules unrelated to previously described myelin proteins, or do not synthesize appropriate axon growth promoting molecules. They also reveal that, for axon regeneration, central nervous system and peripheral sensory neurons require distinct substratum interactions.
Monocularly Induced 2‐Deoxyglucose Patterns in the Visual Cortex and Lateral Geniculate Nucleus of the Cat: II. Awake Animals and Strabismic Animals
Authors: Löwel Siegrid , Singer Wolf 
Published: April 2006

AbstractIn the course of experiments studying the organization of ocular dominance columns in the visual cortex of cats, we noticed that—contrary to common belief—labelling with 2‐deoxyglucose after monocular stimulation failed to induce a pattern of ocular dominance columns but resulted in a rather homogeneous 2‐deoxyglucose uptake throughout area 17 in anaesthetized and paralysed animals. We wondered whether 2‐deoxyglucose columns could be obtained in awake animals and/or in strabismic animals, which have a more pronounced segregation of ocular dominance columns. To this end, we investigated 2‐deoxyglucose patterns after monocular stimulation in three groups of animals: (i) in awake normally reared cats, (ii) in awake strabismic cats and (iii) in anaesthetized and paralysed strabismic cats. Additionally, we labelled ocular dominance columns with intraocular [3H]proline injections. In all cats, monocular stimulation induced 2‐deoxyglucose patterns that were in precise register with the proline‐labelled ocular dominance columns in layer IV. Regions of increased 2‐deoxyglucose uptake extended in a columnar fashion through all cortical layers. In contrast to normally reared animals, in strabismic cats, the expression of 2‐deoxyglucose labelled ocular dominance columns was not abolished by anaesthesia or paralysis. However, there was a difference between the 2‐deoxyglucose patterns in the awake normally reared cats and the strabismic animals. In the former, the patches of 2‐deoxyglucose labelling were smaller and occupied less territory than the afferents of the stimulated eye in layer IV. Together with the results of the previous study, these data indicate that in awake normally reared and in awake and anaesthetized strabismic cats, but not in anaesthetized and paralysed normally reared animals, monocular stimulation activates selectively neurons in columns that are in register with the termination sites of afferents from the stimulated eye. This suggests the existence of a mechanism in normally reared animals which restricts cortical activation after monocular stimulation to territories that are in register with the afferents from the stimulated eye. This mechanism appears to be effective only when the animals are awake and actively exploring their environment. This and the fact that the active columns were narrower than the terminal fields of the stimulated eye suggest an active inhibitory process, perhaps related to mechanisms of selective attention. The observation that ocular dominance columns persist in strabismic cats even under anaesthesia can be accounted for by the lack of binocular convergence in these animals.
Visually Triggered Neuronal Oscillations in the Pigeon: An Autocorrelation Study of Tectal Activity
Authors: Neuenschwander Sergio , Varela Francisco J. 
Published: April 2006

AbstractIn this study we describe visually triggered gamma oscillations in the optic tectum of awake pigeons. This study was motivated by the potential relevance of synchronous oscillatory responses in perceptual binding in a laminated structure other than the mammalian neocortex. Tectal responses were recorded as local field potential and multiunit activity by differential filtering. The local field potential was analysed by computing its autocorrelation function and spectral power with a moving window applied to single response sweeps. The temporal structure of the spike trains was evaluated by computing averaged autocorrelograms. A damped sine wave function was fitted to the autocorrelograms in order to quantify the degree of oscillation of both signals. Epochs of significant oscillatory activity were observed in the local field potential in 60% of the trials (n= 39). In all trials, significant oscillations occupied ∼ 10% of the time the stimulus was present. The oscillatory events in both the local field potential and the multiunit activity had frequencies in the range of 20 – 50 Hz. It is important to emphasize the great variability in the frequency and in the probability of occurrence of the oscillatory responses from trial to trial, which makes the oscillatory behaviour of the tectal activity highly non‐stationary. The oscillatory activity we describe in the avian tectum has characteristics similar to those reported in the mammalian neocortex. These findings from a fully awake animal strengthen the universality of oscillations as a possible carrier for synchronization of activity in the constitution of neuronal assemblies.
The Isolated and Perfused Brain of the Guinea‐pig In Vitro
Authors: Mühlethaler M. , de Curtis M. , Walton K. , Llinás R. 
Published: April 2006

AbstractWe describe here an isolated and perfused in vitro adult guinea‐pig whole brain preparation which is an extension of the previously described in vitro brainstem–cerebellum preparation, Viability was tested by the analysis of trans‐synaptic responses along the visual pathways following the electrical stimulation of the optic nerve or the optic radiations. The evoked field potentials were recorded in the dorsal lateral geniculate, the superior colliculus and the visual cortex. The distribution of extracellular currents was studied using current source density analysis, in order to determine the amplitude, time course and spatial organization of the synaptic activity at these sites. The study indicates that field potentials were very similar to those described in vivo. These data demonstrate the survival of a complex adult sensory system in vitro and suggest that this preparation can be used for the analysis of multisynaptic circuits in the mammalian brain.