bluuebunny/crossref_metadata_2025_split huggingface dataset:
Consequences of Transient Focal Cerebral Ischaemia for Second Messenger and Neurotransmitter Binding in the Rat: Quantitative Autoradiographic Analysis of Forskolin, Dopamine D1 Receptor Binding and Cerebral Blood Flow Changes
Authors: Gartshore Gail , Dawson Deborah , Patterson James , Macrae I. Mhairi 
Published: April 2006

AbstractIn order to study the consequences of reperfusion for ischaemic brain injury, quantitative ligand binding autoradiography was carried out in a model of reversible focal cerebral ischaemia. Endothelin‐1 applied to the abluminal surface of the middle cerebral artery in anaesthetized Sprague‐Dawley rats induced severe focal ischaemia and subsequent reperfusion (assessed by blood flow tracers [99mTc]HMPAO and [14C]iodoantipyrine respectively) by 2 h after insult. Ligand binding autoradiography on consecutive sections demonstrated these blood flow changes to be associated with a significant reduction in forskolin binding throughout the middle cerebral artery territory (e.g. 25% in parietal cortex, 11% in dorsolateral caudate nucleus). The most marked losses in forskolin binding were in areas where ischaemia was severe and reperfusion was poor. However, the same changes in cerebral blood flow had no significant effect on D1 dopamine receptor binding (e.g. >2% reduction in the caudate nucleus). These data demonstrate that ligand binding characteristics are significantly affected as early as 2 h after insult, with evidence of differential sensitivity for forskolin and D1 dopamine binding. With regard to the consequences of reperfusion, comparison with our previous study of 2 h maintained ischaemia demonstrates reperfusion‐related salvage of dopamine and forskolin binding in the caudate nucleus but possible exacerbation of forskolin binding loss in the cortex.
Distribution of Components of the SNARE Complex in Relation to Transmitter Release Sites at the Frog Neuromuscular Junction
Authors: Boudier Jeanne‐Andrée , Charvin Nathalie , Boudier Jean‐Louis , Fathallah Mohammed , Tagaya Mitsuo , Takahashi Masami , Seagar Michael J. 
Published: April 2006

AbstractAt the frog neuromuscular junction, neurotransmitter release sites are regularly spaced at 1 μm intervals along the nerve terminal, directly facing postsynaptic folds which contain a high density of acetylcholine receptors. Immunostaining and laser confocal scanning microscopy were used to compare the distribution of presynaptic proteins implicated in exocytosis with that of fluorescent α‐bungarotoxin. Syntaxin, synaptosome‐associated 25 kDa protein and calcium channels were located predominantly at release sites. Synaptobrevin (vesicle‐associated membrane protein) was distributed in the cytoplasm of the nerve terminal, presumably in the packets of microvesicles associated with each active zone. N‐Ethylmaleimide‐sensitive fusion protein (NSF) and soluble NSF attachment proteins (αβSNAP) displayed a diffuse distribution throughout the terminal cytoplasm and also colocalized in distinct concentrated zones adjacent to the presynaptic membrane.
Localization of Dopamine D2 Receptor in Rat Spinal Cord Identified with Immunocytochemistry and In Situ Hybridization
Authors: van Dijken Henk , Dijk Jan , Voorn Pieter , Holstege Jan C. 
Published: April 2006

AbstractIn the present study the distribution of dopamine D2 receptors in rat spinal cord was determined by means of immunocytochemistry using an anti‐peptide antibody, directed against the putative third intracellular loop of the D2 receptor and in situ hybridization (ISH) using a [35S]UTP labelled anti‐sense riboprobe. With the immunocytochemical technique, labelling was confined to neuronal cell bodies and their proximal dendrites. Strongest labelling was present in the parasympathetic area of the sacral cord and in two sexually dimorphic motor nuclei of the lumbosacral cord, the spinal nucleus of the bulbocavernosus and the dorsolateral nucleus. Moderately labelled cells were present in the intermediolateral cell column, the area around the central canal and lamina I of the dorsal horn. Weak labelling was present in the lateral spinal nucleus and laminae VII and VIII of the ventral horn. Except for the two sexually dimorphic motornuclei of the lumbosacral cord labelled motoneurons were not encountered. With the ISH technique radioactive labelling was present in many neurons, indicating that they contained D2 receptor mRNA. The distribution of these neurons was very similar to the distribution obtained with immunocytochemistry, but with ISH additional labelled cells were detected in laminae III and IV of the dorsal horn, which were never labelled with immunocytochemistry. The present study shows that the D2 receptor is expressed in specific areas of the rat spinal cord. This distribution provides anatomical support for the involvement of D2 receptors in modulating nociceptive transmission and autonomic control. Our data further indicate that D2 receptors are not directly involved in modulating motor functions with the exception, possibly, of some sexual motor functions.
Long‐term Depression of Horizontal Connections in Rat Motor Cortex
Authors: Hess Grzegorz , Donoghue John P. 
Published: April 2006

AbstractThe possibility for long‐term depression (LTD) of synaptic transmission in layer 11/11 I horizontal connections within motor cortex was investigated using field potentials and intracellular recordings in rat brain slices. The LTD was induced by low‐frequency stimulation at 2 Hz for 10 min in sites displaced horizontally by 0.5 mm from the stimulating electrode. Response amplitude measured 25‐30 min after 2 Hz stimulation ended was 79% of baseline values (n= 13) at half maximal stimulation and 59% when 2 Hz stimulus intensity was doubled (n= 10). In 13/15 tested cases LTD in horizontal connections was specific to the activated pathway. Intracellular recordings from six neurons confirmed synaptic character of response depression. Horizontal connections in which LTD was induced retained the capability of increasing synaptic strength. Long‐term potentiation could be induced in previously depressed pathways by simultaneous theta burst stimulation of two converging horizontal inputs combined with transient local application of GABAA receptor antagonist bicuculline methiodide (mean increase: 45 ± 8%, n = 6) or by simultaneous theta burst stimulation of converging horizontal and vertical inputs (mean change: 26 5 6%, n = 5). These data demonstrate that activity‐dependent mechanisms may regulate bidirectionally the effectiveness of horizontal synaptic coupling between cortical neurons, thus forming a potential mechanism for plasticity of cortical connections and the representation patterns they support.
Hydroxyindole‐O‐methyltransferase in the Chicken Retina: Immunocytochemical‐ Localization and Daily Rhythm of mRNA
Authors: Guerlotté Jérôme , Grève Pierre , Bernard Marianne , Grechez‐Cassiau Aline , Morin Fabrice , Collin Jean‐Pierre , Voisin Pierre 
Published: April 2006

AbstractIn the vertebrate retina and pineal gland, melatonin production displays diurnal variations with high levels at night. Hydroxyindole‐O‐methyltransferase (HIOMT, EC 2.1.1.4) catalyses the last step of melatonin biosynthesis. In the present study, a cDNA encoding chicken HIOMT was used to examine the effects of environmental lighting on HIOMT mRNA expression in the chicken retina. A day/night rhythm of HIOMT mRNA level was observed, with an average 5‐fold increase during the night. Light strongly suppressed the night‐time rise in HIOMT mRNA concentration while darkness prevented its daytime fall. An antibody directed against chicken HIOMT was used for immunocytochemical identification of retinal melatoninergic cells. HIOMT immunoreactivity could be observed in rods as well as in cones. However, the lowest levels of HIOMT immunoreactivity were always observed in the accessory cones of double cones. A few HIOMT‐positive cell bodies could also be observed in the inner nuclear layer. Altogether, these data indicate that HIOMT gene expression in the retina is organized on a daily basis as a direct response to light, and that the different types of photoreceptors may not be equally involved in melatonin production.
Regulation of Intracellular Ca2+ in Response to Muscarinic and Glutamate Receptor Agonists During the Differentiation of NTERA2 Human Embryonal Carcinoma Cells into Neurons
Authors: Squires P. E. , Wakeman J. A. , Chapman H. , Kumpf S. , Fidock M. D. , Andrews P. W. , Dunne M. J. 
Published: April 2006

AbstractSingle cell microfluorimetry was used to study intracellular calcium ion signals ([Ca2+]i) evoked by acetylcholine (ACh), glutamate receptor agonists and by KCI‐induced membrane depolarization, during neuronal differentiation of the human embryonal carcinoma (EC) cell line, NTERA2. In undifferentiated NTERA2 EC cells, [Ca2+]i) was elevated in response to ACh, but not to the glutamate receptor agonists NMDA, kainate or AMPA. The ACh‐induced rise in [Ca2+]i) was dependent upon both Ca2+ influx and Ca2+ mobilization from cytoplasmic calcium stores. Three other human EC cell lines responded similarly to ACh but not to glutamate or KCI‐induced depolarization. In neurons derived from NTERA2 cells by retinoic acid induction, [Ca2+]i) signals were evoked by ACh, NMDA, kainate and by an elevation of the extracellular KCI concentration. As in undifferentiated EC cells, the ACh‐mediated increases in [Ca2+li were governed by both Ca2+ influx and Ca2+ mobilization. In contrast, the effects of NMDA, kainate and KCI did not involve intracellular Ca2+ mobilization. The appearance of glutamate and KCI responsiveness was not detected in non‐neuronal differentiated derivatives of NTERA2 cells. Using a number of pharmacologically defined muscarinic receptor antagonists we found that NTERA2 EC cells express M1, M3, M4 and possibly M5 receptor subtypes linked to changes in [Ca2+]i), whilst only M3 and M5 are present in NTERA2‐derived neurons. The results were supported by PCR analysis of the muscarinic mRNA species expressed in the cells. The data demonstrate that differentiation of NTERA2 EC cells into neurons involves the induction of functional glutamate receptors coupled to rises in [Ca2+]i), and changes in the expression of muscarinic ACh receptor subtypes.
Localization of Glial Cell Line‐derived Neurotrophic Factor (GDNF) mRNA in Embryonic Rat by In Situ Hybridization
Authors: Suvanto Petro , Hiltunen Jukka O. , Arumäe Umas , Moshnyakov Maxim , Sariola Hannu , Sainio Kirsi , Saarrna Mart 
Published: April 2006

AbstractThe localization of glial cell line‐derived neurotrophic factor (GDNF) mRNA was studied by in situhybridization in rat from embryonic (E) day E10 to E15. At E10, GDNF mRNA is found in the urogenital field and the cranial part of the gut. At E11, the most abundant expression of GDNF mRNA is seen in the epithelial cells of the second, third and fourth pharyngeal pouches, the third and fourth pharyngeal arches and pharynx. Also mesenchymal cells of the gut and mesonephric tubules contain GDNF mRNA. At E13, expression is observed in the mesenchymal cell layers of the oesophagus, intestine and stomach, the mesenchymal cells around the condensing cartilages and metanephric kidney mesenchyme. Also, the epithelia of Rathke's pouch and pharynx are intensely labelled. High expression of GDNF mRNA continues at El5 in kidney, gastrointestinal tract and cartilage. At that stage, GDNF mRNA is seen also in whisker pad and skeletal muscles. The distribution of GDNF mRNA in embryonic rat suggests important roles for GDNF in the early differentiation of the kidney tubules, the innervation of the gastrointestinal tract and the differentiation process of the cartilage and muscle. Our results indicate novel functions for GDNF outside the nervous system.
The Plasma Membrane Protein SNAP‐25, but not Syntaxin, is Present at Photoreceptor and Bipolar Cell Synapses in the Rat Retina
Authors: Brandstätter J. H. , Wässle H. , Betz H. , Morgans C. W. 
Published: April 2006

AbstractThe two neuronal plasma membrane proteins synaptosomal associated protein 25 kDa (SNAP‐25) and syntaxin form, in current models of synaptic vesicle exocytosis, a docking complex on the presynaptic plasma membrane. This docking complex interacts with the integral synaptic vesicle protein, synaptobrevin. We have examined, in the rat retina, the distribution of SNAP‐25 and syntaxin using light and electron microscopic immunocytochemistry. SNAP‐25 immunoreactivity was present in the outer and inner nuclear layers at the membranes of photoreceptor and amacrine cell somata, in the outer plexiform layer in the terminals of photoreceptor cells and throughout the inner plexiform layer in the terminals of bipolar and amacrine cells. In contrast, syntaxin immunoreactivity was not found in the terminals of photoreceptor and bipolar cells, but only in the terminals of amacrine cells. Because of the absence of detectable syntaxin from the terminals of photoreceptor and bipolar cells, we propose that either a novel syntaxin isoform or a syntaxin–like protein exists at the ribbon synapses formed by these neurons.
Reserpine Affects Differentially the Density of the Vesicular Monoamine Transporter and Dihydrotetrabenazine Binding Sites
Authors: Naudon L. , Raisman‐Vozari R. , Edwards R. H. , Leroux‐Nicollet I. , Peter D. , Liu Y. , Costentin J. 
Published: April 2006

AbstractWe have studied the effect of a single injection of reserpine (5 mg/kg, s.c.) on the synaptic vesicle monoamine transporter (VMAT) density in the rat striatum, using two labelling procedures: radioimmunolabelling with an antibody against VMAT, and binding of the specific ligand [3H]dihydrotetrabenazine ([3H]TBZOH). In the rostral and medial striatum, the distribution of VMAT immunoreactivity displayed the highest density in the lateral subregions. In the caudal part of the striatum, VMAT immunoreactivity showed increasing density from dorsal to ventral subregions. The VMAT immunoreactivity was not altered 2 and 30 days after the reserpine injection, whereas [3H]TBZOH binding site density, measured on adjacent slices, showed a dramatic decrease at day 2 and a moderate recovery at day 30, suggesting that despite a persistent blockade of [3H]TBZOH binding sites, VMAT protein density was unchanged.
The Effects of Neonatal Dorsal Root Section on the Survival and Dendritic Development of Lumbar Motoneurons in the Rat
Authors: O'Hanlon G. M. , Lowrie M. B. 
Published: April 2006

AbstractPeripheral nerve crush during the early neonatal period results in the death of a large proportion of affected motoneurons and abnormal dendritic development in those which survive. The present study reports the effects of neonatal dorsal root section on motoneurons supplying the extensor digitorum longus muscle of the rat. This lesion did not result in motoneuron death, but did disrupt subsequent dendritic development. In cells retrogradely labelled with cholera toxin subunit B conjugated to horseradish peroxidase, there was little change in adult dendritic morphology in the transverse plane, where abnormalities associated with loss of efferent contact and cell death have been found. However, there was a caudal expansion of the dendritic field, an effect seen following nerve crush but not after blockade of neuromuscular transmission alone. The results show that disruption of dorsal root sensory inputs alone can affect the dendritic development of motoneurons but does not cause their death. In conjunction with our earlier findings, it is clear that both afferent and efferent connections are required for normal dendritic development, and disruption of either has a characteristic effect on survival and dendritic morphology.
Neurite Outgrowth on Non‐permissive Substrates In Vitro is Enhanced by Ectopic Expression of the Neural Adhesion Molecule L1 by Mouse Astrocytes
Authors: Mohajeri M. Hasan , Bartsch Udo , van der Putten Herman , Sansig Gilles , Mucke Lennart , Schachner Melitta 
Published: April 2006

AbstractAxonal regrowth in the lesioned central nervous system (CNS) of adult mammals is, in part, prevented by non‐permissive properties of glial cells and myelin. To test if ectopic expression of the neurite outgrowth promoting recognition molecule L1 will overcome these non‐permissive influences and promote neurite outgrowth, L1 was expressed in astrocytes of transgenic mice using regulatory sequences of the glial fibrillary acidic protein (GFAP) gene. Northern blot analysis of different transgenic lines revealed different levels of transgenically expressed L1. Cultured astrocytes derived from transgenic animals displayed L1 immunoreactivity at the cell surface and in situ hybridization and immunocytochemical analysis of optic nerves from adult transgenic mice localized L1 expression to astrocytes. Expression of L1 protein by transgenic astrocytes was significantly upregulated in lesioned optic nerves. When mouse small cerebellar neurons or chick dorsal root ganglion neurons were cultured on cryosections of lesioned optic nerves or astrocyte monolayers from transgenic mice, respectively, neurite outgrowth was increased up to 400% on tissue sections and 50% on astrocytes compared with similar preparations from non‐transgenic mice. The increase in neurite outgrowth on tissue sections or astrocyte monolayers from different transgenic lines was proportional to the different levels of L1 expression. Moreover, increased neurite outgrowth on these substrates was specifically inhibited by polyclonal L1 antibodies. In vivo, rescue of severed axons was enhanced in transgenic versus wild type animals, while regrowth of axons was slightly, but not significantly, increased. Together, our observations demonstrate that L1 promotes neurite outgrowth when expressed ectopically by astrocytes and that L1 is able to overcome, at least partially, the non‐permissive substrate properties of differentiated CNS glial cells in vitro.
Reversible Inhibitory Effects of Interferon‐γ and Tumour Necrosis Factor‐α on Oligodendroglial Lineage Cell Proliferation and Differentiation In Vitro
Authors: Agresti Cristina , D'Urso Donatella , Levi Giulio 
Published: April 2006

AbstractWe have investigated the effects of the two prominent inflammatory cytokines, interferon‐γ (IFN‐γ) and tumour necrosis factor‐α (TNF‐α), on oligodendroglial lineage cell development and survival. Purified oligodendrocytes and oligodendrocyte precursors obtained from neonatal rat brain primary cultures were subcultured in a defined, serum‐free medium and exposed to IFN‐γ (1‐100 U/ml), TNF‐α (25‐100 ng/ml) or both (100 U/ml and 50 ng/ml respectively) from day 1 to day 3 or from day 3 to day 6. While cell survival was not affected in any of the conditions tested, IFN‐γ dose‐dependently inhibited [3H]thymidine or bromodeoxyuridine incorporation (by up to 50%) and the reduction of the tetrazolium salt 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT; by up to 33%). TNF‐α synergized with IFN‐γ, but was ineffective by itself. Moreover, IFN‐γ totally antagonized the induction by basic fibroblast growth factor and platelet‐derived growth factor of the proliferation of the oligodendroglial lineage cell population under study. IFN‐γ also blocked the differentiation of oligodendrocyte precursors, as evidenced by cell morphology, immunostaining for early and late differentiation markers (galactocerebroside and myelin basic protein respectively) and activity of ceramide galactosyl transferase. Again, the effect of IFN‐γ was potentiated by TNF‐α, which was ineffective when tested alone. The inhibitory activity of IFN‐γ was rapidly reversible: 3 days after removal of the cytokine, administered from day 1 to day 3, complete recovery of cell proliferation and differentiation could be documented. The cytokine‐induced arrest in the expression of differentiation antigens was accompanied by perturbations in the expression of the corresponding mRNAs, revealed by a semiquantitative reverse transcription‐polymerase chain reaction method. In particular, the message for myelin basic protein (and, in the case of treatment from days 3 to 6, also that for myelin associated glycoprotein) was decreased in cultures exposed to IFN‐γ, and further depressed in cultures treated with IFN‐γ and TNF‐α, while TNF‐α alone was ineffective. The above observations may help explain the role of IFN‐γ and TNF‐α in the pathogenesis of inflammatory demyelinating diseases, in which increases in the levels of these substances have been described. In particular, in the case of multiple sclerosis, our results may bear on the problem of defective remyelination and are consistent with the frequent relapsing‐remitting course of the disease.
The Distribution of Brain‐derived Neurotrophic Factor and its Receptor trkB in Parvlbumin‐containing Neurons of the Rat Visual Cortex
Authors: Cellerino Alessandro , Maffei Lamberto , Domenici Luciano 
Published: April 2006

AbstractWe analysed the distribution of brain‐derived neurotrophic factor (BDNF) and its receptor trkB in the adult rat visual cortex, paying particular attention to a GABAergic neuronal subpopulation—the parvalburnin‐positive cells. We found expression of trkB in the cell body and apical dendrite of pyramidal neurons and in the cell body of non‐pyramidal neurons. Double labelling experiments revealed extensive colocalization of parvalbumin and trkB immunoreactivity in non‐pyramidal neurons. Interestingly, the trkB‐positive pyramidal neurons appeared surrounded by parvalbumin‐labelled boutons. The use of double immunohistochemistry and in situ hybridization histochemistry showed that parvalbumin‐positive neurons express trkB mRNA. BDNF rnRNA was found in several cells. Coexpression of BDNF mRNA and parvalbumin immunoreactivity was extremely rare. These data strongly suggest that BDNF synthesized by cortical neurons acts as a postsynaptically derived factor for parvalbumin‐positive neurons in the adult rat visual cortex.
Glial Cell Line‐derived Neurotrophic Factor: the Lateral Cerebral Ventricle as a Site of Administration for Stimulation of the Substantia Nigra Dopamine System in Rats
Authors: Martin D. , Miller G. , Fischer N. , Dix D. , Cullen T. , Russell D. 
Published: April 2006

AbstractThe direct application of recombinant human glial cell line‐derived neurotrophic factor (rhGDNF) to the deep structures of the nigrostriatum has been shown previously to augment dopamine function and inhibit loss of substantia nigra neurons in rodent models of Parkinson's disease. The present studies were designed to determine whether administration of rhGDNF into the lateral ventricle, a more clinically accessible intracranial target, is capable of augmenting dopamine function of the nigrostriatal pathway in normal rats. Single bolus intracerebroventricular (i.c.v.) injections of rhGDNF increased locomotor activity and decreased food and water consumption and body weight gain in a dose‐dependent manner. rhGDNF increased concentrations of dopamine and dopamine metabolites in the substantia nigra, ventral tegmental area and hypothalamus, but had no significant effects in the striatum. rhGDNF had no effect on striatal or substantia nigral serotonin (5‐HT) and 5‐hydroxyindoleacetic acid levels, but these levels were significantly increased in the ventral tegmental area and hypothalamus respectively. The augmentation of the dopamine and 5‐HT systems was detected 2 weeks but not 3 days or 6 weeks after rhGDNF administration. After a repeat injection of i.c.v. rhGDNF (6 weeks after the initial injection), substantia nigral dopamine, 5‐HIAA and noradrenalin levels were increased. These results indicate that i.c.v. administration of rhGDNF has an influence on adult rat dopamine neurons. This route of administration may be useful for stimulating dopamine neurons in Parkinson's disease.