bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transient action of the endothelial constitutive nitric oxide synthase (ecNOS) mediates the development of thermal hypersensitivity following peripheral nerve injury
Authors: Levy Dan , Tal Michael , Höke Ahmet , Zochodne Douglas W. 
Published: March 2003

AbstractNeuropathic pain is a disabling feature of peripheral nerve injury. Following injury, local inflammation and the release of mediators may contribute to ectopic mechanosensitivity of the nerve‐trunk and pain hypersensitivity. In the present study we investigated whether nitric oxide (NO) action and local nitric oxide synthase (NOS) expression play a role in pain hypersensitivity and A fibre‐mediated ectopic hyperexcitability following a chronic constriction injury to a rat sciatic nerve. Using immunohistochemical methods we provide evidence for a unique endothelial constitutive nitric oxide synthase (ecNOS) immunoreactivity localized in early axonal endbulb‐like structures of injured peripheral nerve axons. Moreover, we show that following nerve injury there is increased ecNOS‐mRNA expression within the lumbar sympathetic ganglia, and that axoplasmic transport in sympathetic and other axons rather than local non‐neural synthesis accounts for its accumulation in nerve fibres. We also demonstrate here that local inhibition of NOS action with the broad‐spectrum inhibitor NG‐nitro‐l‐arginine‐methyl ester (l‐NAME), but not more specific inhibitors of other NOS isoforms, has stereospecific, dose‐ and time‐dependent analgesic effects that were reversed by local administration of l‐arginine, the natural precursor of NO. In further work, using a teased fibre preparation, we show that administration of l‐NAME, but not d‐NAME, to the injury site also blocks ectopic mechanosensitivity of injured A‐fibres. Our results indicate that an early and transient local ecNOS expression within early axonal endbulb‐like structures, some arising from sympathetic axons, plays a critical role in the development of neuropathic pain.
Upregulation of metabotropic glutamate receptor subtype mGluR3 and mGluR5 in reactive astrocytes in a rat model of mesial temporal lobe epilepsy
Authors: Aronica Eleonora , Van Vliet Erwin A. , Mayboroda Oleg A. , Troost Dirk , Da Silva Fernando H. Lopes , Gorter Jan A. 
Published: March 2003

AbstractReactive gliosis is a prominent morphological feature of mesial temporal lobe epilepsy. Because astrocytes express glutamate receptors, we examined changes in metabotropic glutamate receptor (mGluR) 2/3, mGluR5 and transforming growth factor (TGF)‐β in glial cells of the hippocampal regions in an experimental rat model of spontaneous seizures. Rats that exhibited behavioural status epilepticus (SE) directly after 1 h of electrical angular bundle stimulation, displayed chronic spontaneous seizures after a latent period of 1–2 weeks as observed using continuous electrographic monitoring. SE resulted in hypertrophy of astrocytes and microglia activation throughout the hippocampus as revealed by immunolabelling studies. A dramatic, seizure intensity‐dependent increase in vimentin immunoreactivity (a marker for reactive astrocytes) was revealed in CA3 and hilar regions where prominent neuronal loss occurs. Increased vimentin labelling was first apparent 24 h after onset of SE and persisted up to 3 months. mGluR2/3 and mGluR5 protein expression increased markedly in glial cells of CA3 and hilus by 1 week after SE, and persisted up to 3 months after SE. Double immunolabelling of brain sections with vimentin confirmed co‐localization with glial fibrillary acidic protein (GFAP), mGluR2/3 and mGluR5 in reactive astrocytes. TGF‐β, a cytokine implicated in mGluR3‐mediated neuroprotection, was also upregulated during the first 3 weeks after SE throughout the hippocampus. This study demonstrates seizure‐induced upregulation of two mGluR subtypes in reactive astrocytes, which − together with the increased production of TGF‐β − may represent a novel mechanism for modulation of glial function and for changes in glial‐neuronal communication in the course of epileptogenesis.
Evidence for glutamatergic tectotectal neurons in the cat superior colliculus: a comparison with GABAergic tectotectal neurons
Authors: Olivier E. , Corvisier J. , Pauluis Q. , Hardy O. 
Published: March 2003

AbstractThe tectotectal commissural pathway is commonly regarded as responsible for the reciprocal inhibition that takes place between the two superior colliculi (SC). Although this hypothesis has received strong support from electrophysiological studies, more recent investigations have suggested that some collicular cells, e.g. fixation neurons, may establish excitatory connections with cells in the contralateral SC through the collicular commissure. The goal of the present study was to seek immunohistochemical evidence for glutamatergic tectotectal cells in the cat SC by using a double‐labelling technique. Tectotectal cells were retrogradely labelled with wheat germ agglutinin (WGA) –horseradish peroxidase (HRP) coupled to colloidal gold injected in the contralateral SC, and neurons containing glutamate or γ‐aminobutyric acid (GABA) were then identified with immunohistochemical techniques. The present study provides evidence that, in the cat SC, equal numbers of tectotectal cells are immunopositive to glutamate and GABA, suggesting that the tectotectal pathway may consist of two distinct functional components. The finding that an equal number of tectotectal cells are GABAergic and glutamatergic is somewhat surprising as electrophysiological studies have invariantly indicated that the inhibitory component of the tectotectal projection predominates. Another striking feature of the GABAergic and glutamatergic tectotectal cell populations is their identical topographic distribution in the SC. These results suggest that not only cells in the rostral fixation zone establish excitatory connections with the contralateral SC. Tectotectal projections could be potentially important to shape the spatial pattern of saccade‐related activity that may occur simultaneously in the two SC during vertical and oblique orienting movements.
Retinal ganglion cells projecting to the nucleus of the optic tract and the dorsal terminal nucleus of the accessory optic system in macaque monkeys
Authors: Telkes I. , Distler C. , Hoffmann K. ‐P. 
Published: March 2003

AbstractUsing classical neuroanatomical retrograde tracing methods we investigated the retinal ganglion cells projecting to the nucleus of the optic tract and dorsal terminal nucleus of the accessory optic system (NOT‐DTN) in macaque monkeys. Our main aim was to quantify the strength of the projection from the ipsilateral retina to the NOT‐DTN. We therefore examined the number, distribution, and soma size of retinal ganglion cells involved in this projection. Electrophysiologically controlled small injections into the NOT‐DTN revealed a clearly bilateral retinal projection originating mainly from the central retina but also involving peripheral retinal regions. Labelled cells were found nasally in the contralateral retina and temporally in the ipsilateral retina with some overlap in the fovea. The projection from the ipsilateral retina was 36–43% of that from the contralateral retina. On average, only 1–6% of the local population of ganglion cells projected to the NOT‐DTN. Small soma size and large dendritic fields imply that in monkey rarely encountered, ‘specialized’ ganglion cells provide the direct retinal input to the accessory optic system (AOS). These results are discussed with respect to the symmetry of monocular horizontal optokinetic nystagmus (OKN) in primates.
Dedifferentiation of intrinsic response properties of motoneurons in organotypic cultures of the spinal cord of the adult turtle
Authors: Perrier Jean‐François , Noraberg Jens , Simon Magda , Hounsgaard Jørn 
Published: March 2003

AbstractExplant cultures from the spinal cord of adult turtles were established and used to study the sensitivity of the intrinsic response properties of motoneurons to the changes in connectivity and milieu imposed by isolation in culture. Transverse sections 700 μm thick were explanted on cover slips and maintained in roller‐tube cultures in medium containing serum and the growth factors brain‐derived neurotrophin factor (BDNF), neurotrophin‐3 (NT3), glial cell line‐derived neurotrophic factor (GDNF) and ciliary neurotrophic factor (CNTF). The gross morphology of acute sections was maintained after 4 weeks in culture. Cell bodies of motoneurons remained stainable in fixed cultures with an antibody against choline acetyltransferase (ChAT) throughout the culture period. During culture, motoneurons maintained stable resting membrane potentials and were contacted by functional synapses. The ability to generate action potentials was also preserved as was delayed inward rectification and generation of calcium spikes in the presence of tetra‐ethyl ammonium (TEA). In response to depolarization, however, motoneurons presented strong outward rectification, and only 41% of the cells recorded from maintained the ability to fire repetitively. By the second week in culture, a fraction of motoneurons displayed fast and slow transient outward rectification and low‐threshold calcium spikes, features not seen in turtle motoneurons in acute slices. On the other hand, properties mediated by L‐type Ca2+ channels disappeared during the first few days in culture. Our observations show that the phenotypical intrinsic response properties of mature spinal motoneurons are modified in explant cultures. The properties acquired resemble the properties in juvenile motoneurons in several species of terrestrial vertebrates.
The morphological development of neurons derived from EGF‐ and FGF‐2‐driven human CNS precursors depends on their site of integration in the neonatal rat brain
Authors: Rosser Anne E. , Tyers Pamela , Dunnett Stephen B. 
Published: March 2003

AbstractNeural precursor cells derived from the developing human brain were expanded in vitro under the influence of fibroblast growth factor‐2 (FGF‐2) and epidermal growth hormone (EGF), and were then transplanted into different regions of the neonatal rat brain. Four weeks later neurons were seen to have developed from human embryonic precursors, using a human‐specific antibody to tau (htau). There were morphological differences between implanted neurons developing in the hippocampus, striatum and neocortex, which were confirmed by cell volume measurements, although no specific neurochemical phenotypes were identified. Htau‐positive fibres were seen to project extensively along fibre pathways appropriate for the site of neuronal integration. This study demonstrates that, following cell division in vitro, neurons differentiating from human precursor cell populations retain the ability to respond appropriately to regional determinants present in the neonatal rat brain. This is important for the application of such cells in CNS repair strategies, in particular neural transplantation.
Enhancement of persistent Na+current by sea anemone toxin (ATX II) exerts dual action on hippocampal excitability
Authors: Brand Sabine , Seeger Thomas , Alzheimer Christian 
Published: March 2003

AbstractWe used anemone toxin II (ATX II) to study how a selective enhancement of persistent Na+current (INaP) would affect the excitability of CA1 pyramidal neurons in the hippocampal slice. In whole‐cell recordings from CA1 cell somata, local application of ATX II (10 μm) into the stratum pyramidale invariably depolarized the neurons and produced sustained burst discharges with depolarizing plateau potentials of variable amplitude and length. However, the strong excitatory action of ATX II, observed on the single cell level, was not mirrored in field potential recordings from the same hippocampal subfield. The amplitude of the electrically evoked population spike declined, reflecting the decreased availability of fast Na+channels, and the intracellulary recorded burst discharges were not detected by the field electrode. The lacking synchronization of cellular bursting activity was seen during both local and bath application of ATX II, suggesting that the toxin, in addition to promoting burst discharges of individual neurons, simultaneously dampens network excitability. In fact, ATX II reduced afferent fibre volleys (reflecting axonal excitability) and field excitatory postsynaptic potentials (EPSPs) in a similar fashion. As the expression of different Na+channel subtypes appears to be compartmentalized within hippocampal neurons, we propose that point mutations leading to pathologically enhanced INaPmight exert quite opposite effects, depending on the type and location of the Na+channel affected. Whereas alterations of somatodendritic Na+channels would give rise to bursting activity, alterations of axonal Na+channels would primarily decrease network excitability.
Porcine neural progenitors require commitment to the oligodendrocyte lineage prior to transplantation in order to achieve significant remyelination of demyelinated lesions in the adult CNS
Authors: Smith P. M. , Blakemore W. F. 
Published: March 2003

AbstractGlial cell transplantation is a potential therapy for human demyelinating disease, though obtaining large numbers of oligodendrocyte precursors from nonrodent species is currently problematic. Culturing of multipotent neural progenitors may provide a solution to this problem, because these cells can be expanded in vitro whilst retaining the ability to differentiate into both neurons and glial cells. In order to investigate the myelinating capability of multipotent neural progenitors, we isolated cells from the porcine subventricular zone, a region rich in neural progenitors, and transplanted them into areas of persistent demyelination in the spinal cord of immunosuppressed rats, created by the injection of ethidium bromide and subsequent exposure to 40 Gy X‐irradiation. Porcine SVZ cells were transplanted either within 12 h of isolation or after 7 days in B104‐conditioned medium. Freshly isolated cells did not mature into myelinating oligodendrocytes following transplantation and instead remained as clusters of undifferentiated progenitors. However, cells exposed to B104‐conditioned medium prior to transplantation were able to effect complete remyelination of the demyelinated axons. This suggests that neural progenitors must be manipulated in vitro for commitment to the oligodendrocyte lineage prior to transplantation if significant remyelination is to be achieved.
Calcium mobilization elicited by two types of nicotinic acetylcholine receptors in mouse substantia nigra pars compacta
Authors: Tsuneki Hiroshi , Klink Ruby , Léna Clément , Korn Henri , Changeux Jean‐Pierre 
Published: March 2003

AbstractNicotinic acetylcholine receptors (nAChRs) are expressed in the midbrain ascending dopaminergic system, a target of many addictive drugs. Here we assessed the intracellular Ca2+ level by imaging fura‐2‐loaded cells in substantia nigra pars compacta in mouse brain slices, and we examined the influence on this level of prolonged exposures to nicotine using mice lacking the nAChR β2‐subunit. In control cells, superfusion with nicotine (10–100 μm) caused a long‐lasting rise of intracellular Ca2+ level which depended on extracellular Ca2+. This nicotinic response was almost completely absent in β2–/– mutant mice, leaving a small residual response to a high concentration (100 μm) of nicotine which was inhibited by the α7‐subunit‐selective antagonist, methyllycaconitine. Conversely, the α7‐subunit‐selective agonist choline (10 mm) caused a methyllycaconitine‐sensitive increase in intracellular Ca2+ level both in wild‐type and β2–/– mutant mice. Nicotine‐elicited Ca2+ mobilization was reduced by the Na+ channel blocker tetrodotoxin (TTX) and by T‐type Ca2+ channel blocking agents, whereas the choline‐elicited Ca2+ increase was insensitive to TTX. Neither nicotine nor choline produced Ca2+ increase following inhibition of the release of Ca2+ from intracellular stores by dantrolene. These results demonstrate that in nigral dopaminergic neurons, nicotine can elicit Ca2+ mobilization via activation of two distinct nAChR subtypes: that of β2‐subunit‐containing nAChR followed by activation of Na+ channel and T‐type Ca2+ channels, and/or activation of α7‐subunit‐containing nAChR. The Ca2+ influx due to nAChR activation is subsequently amplified by the recruitment of intracellular Ca2+ stores. This Ca2+ mobilization may possibly contribute to the long‐term effects of nicotine on the dopaminergic system.
SDF‐1α‐mediated modulation of synaptic transmission in rat cerebellum
Authors: Limatola Cristina , Giovannelli Aldo , Maggi Laura , Ragozzino Davide , Castellani Loriana , Ciotti Maria Teresa , Vacca Fabrizio , Mercanti Delio , Santoni Angela , Eusebi Fabrizio 
Published: March 2003

AbstractThe functional expression of the seven‐transmembrane domain G protein‐coupled chemokine receptor CXCR‐4/fusin in rat nerve cell was demonstrated by staining with a polyclonal anti‐CXCR‐4 Ab, and by evaluating the calcium responses to the physiological agonist stromal‐derived cell factor‐1α (SDF‐1α) in both cerebellar granule cells in culture and Purkinje neurons (PNs) in cerebellar slices. Cerebellar glial, granule and Purkinje cells showed a pronounced staining for CXCR‐4. Furthermore, cultured granule cells exhibited Ca2+ transients elicited by the application of SDF‐1α, both in cell bodies and in neuronal processes. Whole‐cell patch‐clamped PNs in cerebellar slices responded to SDF‐1α application by a slow inward current followed by an increase of both intracellular Ca2+ level and spontaneous synaptic activity. In particular, the SDF‐1α‐induced slow inward current was considerably reduced by ionotropic glutamate receptor blockers, but developed fully in a medium in which synaptic transmission was inhibited, indicating that this current might be, at least in part, mediated by extrasynaptic glutamate, possibly released from the surrounding glial and/or nerve cells. Taken together, these findings indicate a functional involvement of CXCR‐4 in the modulation of synaptic transmission, adding another member to the repertoire of the chemokine receptors exerting a neuromodulatory role in the cerebellum.
Inflammatory cytokines and related genes are induced in the rat hippocampus by limbic status epilepticus
Authors: De Simoni Maria Grazia , Perego Carlo , Ravizza Teresa , Moneta Daniela , Conti Mirko , Marchesi Francesco , De Luigi Ada , Garattini Silvio , Vezzani Annamaria 
Published: March 2003

AbstractLimbic status epilepticus was induced in rats by unilateral 60‐min electrical stimulation of the CA3 region of the ventral hippocampus. As assessed by RT‐PCR followed by Southern blot analysis, transcripts of interleukin‐1β, interleukin‐6, interleukin‐1 receptor antagonist and inducible nitric oxide synthase were significantly increased 2 h after status epilepticus in the stimulated hippocampus. Induction was maximal at 6 h for interleukin‐1β (445%), interleukin‐6 (405%) and tumour necrosis factor‐α (264%) and at 24 h for interleukin‐1 receptor antagonist (494%) and inducible nitric oxide synthase (432%). In rats with spontaneous seizures (60 days after status epilepticus), interleukin‐1β mRNA was still higher than controls (241%). Immunocytochemical staining of interleukin‐1β, interleukin‐6 and tumour necrosis factor‐α was enhanced in glia with a time‐course similar to that of the respective transcripts. Sixty days after status epilepticus, interleukin‐1β immunoreactivity was increased exclusively in neurons in one third of the animals. Multiple intracerebroventricular injections of interleukin‐1 receptor antagonist (0.5 μg/3 μL) significantly decreased the severity of behavioural convulsions during electrical stimulation and selectively reduced tumour necrosis factor‐α content in the hippocampus measured 18 h after status epilepticus. Thus, the induction of spontaneously recurring seizures in rats involves the activation of inflammatory cytokines and related pro‐ and anti‐inflammatory genes in the hippocampus. These changes may play an active role in hyperexcitability of the epileptic tissue.
Intracerebral infusion of 3H‐dopamine and 3H‐mannitol in the striatum of halothane‐anaesthetized male rats.A dual‐probe microdialysis study of long‐distance diffusion
Authors: Höistad M. , Kehr J. , Andbjer B. , Jansson A. , Fuxe K. 
Published: March 2003

AbstractThis report characterizes an in vivo intracerebral long‐distance diffusion model using dual‐probe microdialysis. Two probes 1 mm apart were implanted into the striatum of control and 6‐hydroxydopamine (6‐OHDA)‐lesioned halothane‐anaesthetized male rats. Either tritiated dopamine (500 n m3H‐DA) or mannitol (1.5 μm3H‐mannitol) was infused continuously for 5 h, while samples were collected from the other probe. Samples (10 μl) were counted by liquid scintillation. For the DA‐infused rats, another 10 μL was separated with high‐pressure liquid chromatography (HPLC)–electrochemical detection into individual fractions containing 3,4‐dihydroxy phenylacetic acid (DOPAC) and homovanillinic acid (HVA), and counted for β‐decay. The total transfer of 3H‐labelled compounds described the overall effect of cellular uptake, metabolism and clearance into the microcirculation, and was compared with that of an extracellular marker, 3H‐mannitol. The migration reached steady‐state levels, generating an equilibrium between delivery and removal from the extracellular space. The half‐time of the steady‐state values, t50%, was in all cases lower in 6‐OHDA‐treated rats compared with control. In addition, the t50% values of 3H‐mannitol were lower than those following the 3H‐dopamine infusion in both control or 6‐OHDA‐lesioned rats. However, it was not possible to detect any unmetabolized 3H‐dopamine at the 1 mm distance. In conclusion, the dual‐probe microdialysis approach proved to be a valid method to study in vivo diffusion and migration in the brain, and the intracerebral spread of compounds highly depends on the nature of the compound infused.