bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Concerted Activity in Parallel Proprioceptive Pathways Controls the Initiation of Co‐activation in the Locust Kick Motor Programme
Authors: Jellema T. , Tait D. S. , Heitler W. J. 
Published: April 2006

AbstractTo jump and kick the locust uses a catapult mechanism implemented by a three‐stage motor programme: initial flexion of the hind tibiae, co‐activation of the antagonist flexor and extensor tibiae motor neurons and trigger inhibition of the flexor motorneurons. The transition from stage 1 to stage 2 thus involves a switch from the normal alternate activation to co‐activation of the antagonist tibiae motorneurons. However, co‐activation has never been observed when the central nervous system has been isolated from the leg. This led us to investigate the possibility that the transition from stage 1 to stage 2 is controlled by a proprioceptive signal. In the first set of experiments intracellular recordings were made in the flexor and extensor motorneurons while the position of the tendon of the femoral chordotonal organ (FCO), which signals tibial position and movement, was experimentally controlled. In these heavily dissected preparations, stretch of the FCO tendon (signalling tibial flexion) was a necessary condition for co‐activation. However, in minimally dissected preparations (in which merely EMG recordings were made), we found that co‐activation occurred even when the FCO was signalling tibial extension, suggesting the involvement of other proprioceptors. A series of experiments were then conducted on minimally dissected preparations to determine the relative contributions of each of the three main hind leg proprioceptors which might signal tibial flexion: the FCO, the lump receptor and Brünners organ. When all three proprioceptors were intact the chance of evoking co‐activation was largest, when all three were eliminated co‐activation could no longer be evoked, irrespective of the level of arousal. Various combinations of partial de‐afferentation showed that the FCO plays the major role, with the lump receptor and Brünners organ playing significant, but progressively less important, roles. We conclude that the three receptors act together as a permissive proprioceptive gate for the kick and jump motor programme, but with a hierarchy of the strengths of their effectiveness.
Adult Nestin‐expressing Subependymal Cells Differentiate to Astrocytes in Response to Brain Injury
Authors: Holmin Staffan , Almqvist Per , Lendahl Urban , Mathiesen Tiit 
Published: April 2006

AbstractThe adult brain contains a small population of central nervous system (CNS) cells in the subependyma which, like embryonic CNS progenitor cells, express the intermediate filament nestin. In this report, the differentiation capacity in vivo of these cells was analysed following a standardized trauma. Before the trauma, the subependymal cells expressed nestin but not the astrocytic and neuronal differentiation markers glial fibrillary acidic protein (GFAP) and neurofilament respectively. In response to injury, the majority of the subependymal cells coexpressed nestin and GFAP, but never nestin and neurofilament. Furthermore, cells coexpressing nestin and GFAP were found progressively further away from the subependyma and closer to the lesion at later time points after the injury, indicating that these cells migrate towards the lesion. Nestin was in addition re‐expressed in reactive astrocytes near the lesion and in non‐reactive astrocytes very far from the lesion throughout the ipsilateral cortex. In conclusion, our data indicate that the nestin‐positive subependymal cells are an in vivo source for the generation of new astrocytes but not neurons after injury, and that nestin re‐expression in astrocytes following traumatic stimuli can be used as a sensitive marker for astroglial activation.
Basolateral Amygdala Lesions Block the Memory‐enhancing Effect of Glucocorticoid Administration in the Dorsal Hippocampus of Rats
Authors: Roozendaal Benno , McGaugh James L. 
Published: April 2006

AbstractThese experiments examined the effects of bilateral amygdala nuclei lesions on modulation of memory storage induced by bilateral intrahippocampal microinfusions of glucocorticoids in male Sprague‐Dawley rats. Post‐training infusions of the glucocorticoid receptor (type II) agonist RU 28362 (3.0 or 10.0 ng) enhanced inhibitory avoidance retention, and infusions of the glucocorticoid receptor antagonist RU 38486 (3.0 or 10.0 ng) administered shortly before training in a water maze spatial task did not affect acquisition, but impaired retention. In both tasks, neurochemically induced lesions of the basolateral but not of the central amygdala blocked the memory‐modulatory effects of the intrahippocampal infusions of the drugs affecting glucocorticoid receptors. Lesions of the central amygdala alone impaired inhibitory avoidance retention, but basolateral amygdala lesions alone did not affect acquisition or retention in either task. These findings are consistent with previous evidence indicating that lesions of the basolateral amygdala block the memory‐modulatory effects of systemically administered glucocorticoids, and provide further evidence that the basolateral amygdala is a critical area involved in regulating glucocorticoid effects in other brain regions involved in memory storage.
5‐Hydroxytryptamine Induces TIS8/egr‐1 and c‐fos Expression in PC12 Cells. Involvement of Tyrosine Protein Phosphorylation
Authors: Humblot Nathalie , Esteve Laurent , Burgun Claude , Aunis Dominique , Zwiller Jean 
Published: April 2006

AbstractThe TIS8/egr‐1 gene is a member of the class of immediate early genes. Originally discovered as a mitogen induced gene, it can also be induced by synaptic activity. We report here the induction of the TIS8/egr‐1 gene by the neurotransmitter 5‐hydroxytryptamine (5‐HT) in cultured rat phaeochromocytoma PC12 cells. Induction was maximal 40 min after addition of 5‐HT to the cells, and declined very rapidly to reach the basal level after 90 min. The electrophoretic mobility‐shift assay showed that induction of the TIS8/egr‐1 gene by 5‐HT was accompanied by increased Egr‐1 protein binding to its DNA consensus sequence. We found an overall correlation of 5‐HT‐induced egr‐1 expression with that of c‐fos expression. The kinetics of the ability of both gene products to bind to their respective DNA consensus sequence was also similar. The 5‐HT‐induced activation in Egr‐1 binding was inhibited by ketanserin and mesulergine, indicating that 5‐HT exerted its action via a 5‐HT2 receptor subtype. The tyrosine protein kinase inhibitor genistein abolished induction of the TIS8/egr‐1 gene, suggesting that tyrosine kinase activity is required for the induction of early genes by 5‐HT. Genistein also inhibited 5‐HT‐induced Egr‐1 binding activity. The increase in phosphotyrosine content of focal adhesion kinase we noticed upon addition of 5‐HT to cells suggests that this cytoplasmic tyrosine protein kinase mediates the effect of 5‐HT in eliciting early gene induction.
Optical Imaging of Cat Auditory Cortex Cochleotopic Selectivity Evoked by Acute Electrical Stimulation of a Multi‐channel Cochlear Implant
Authors: Dinse Hubert R. , Godde Ben , Hilger Thomas , Reuter Gunter , Cords Sven M. , Lenarzl Thomas , von Seelen Werner 
Published: April 2006

AbstractWe measured reflectance changes by means of optical imaging of intrinsic signals to study the effects of acute electrical cochlear stimulation on the topography of the cat auditory cortex. After single‐pulse electrical stimulation at selected sites of a multichannel implant device, we found topographically restricted response areas representing mainly the high‐frequency range in Al. Systematic variation of the stimulation pairs and thus of the cochlear frequency sites revealed a systematic and corresponding shift of the response areas that matched the underlying frequency organization. Intensity functions were usually very steep. Increasingly higher stimulation currents evoked increasingly larger response areas, resulting in decreasing spatial, i.e. cochleotopic, selectivity; however, we observed only slight positional shifts of the focal zones of activity. Electrophysiological recordings of local field potential maps in the same individual animals revealed close correspondence of the locations of the cortical response areas. The results suggest that the method of optical imaging can be used to map response areas evoked by electrical cochlear stimulation, thereby maintaining a profound cochleotopic selectivity. Further experiments in chronically stimulated animals will shed more light on the degree of functional and reorganizational capacities of the primary auditory cortex and could be beneficial for our understanding of the treatment of profound deafness.
Loss of Nerve Endings in the Spinal Dorsal Horn After a Peripheral Nerve Injury. An Anatomical Study in Macaca fascicularis Monkeys
Authors: Liss Anders G. , Wiberg Mikael 
Published: April 2006

AbstractIn patients, the long‐term outcome of injuries to sensory nerves is poor. This is only partly due to mismatching of regenerating axons at the transection site. We found in the macaque monkey that 70% of the transganglionic labelling in the spinal dorsal horn was still significantly reduced 21 months after transection and suturing of the sensory radial nerve. The reduction was evenly distributed throughout the terminal field of nerve endings, which were labelled with a mixture of the intra‐axonal nerve tracer wheat germ agglutinin‐horseradish peroxidase conjugate and pure horseradish peroxidase.
Nitric Oxide Signalling is Required for the Generation of Anoxia‐induced Long‐term Potentiation in the Hippocampus
Authors: Huang Chiung‐Chun , Hsu Kuei‐Sen 
Published: April 2006

AbstractThe involvement of nitric oxide in anoxia‐induced long‐term potentiation (anoxic LTP) of synaptic transmission was investigated in CA1 neurons of rat hippocampal slices using intracellular recording techniques in vitro. In response to superfusion of an anoxic artificial cerebral spinal fluid saturated with 95% N2‐‐5% CO2, the excitatory postsynaptic potential (EPSP) generated in hippocampal CA1 neurons by stimulation of the Schaffer collateral/commissural afferent pathway was completely abolished within 10 min of anoxia. On return to reoxygenated medium, the EPSP returned to the control value within 10 min and was subsequently and progressively potentiated to reach a plateau 15–20 min after return to oxygen. This anoxia‐induced persistent increase in synaptic transmission lasted for more than 1 h. Application of the nitric oxide synthase inhibitors 7‐nitroindazole (7‐NI) or l‐NG‐nitroarginine (NOARG) produced no effects on the baseline EPSP amplitude, but effectively attenuated the anoxic LTP. The inhibitory effects of both 7‐NI and NOARG on the anoxic LTP were blocked by l‐arginine, a substrate for nitric oxide synthase. These results suggest that nitric oxide is required for the generation of anoxia‐induced LTP of glutamatergic synaptic transmission in the CA1 region of the rat hippocampus.
Characterization of a Putative Novel Type of Oligodendrocyte in Cultures from Rat Spinal Cord
Authors: Fanarraga M. L. , Milward E. A. 
Published: April 2006

AbstractOligodendrocytes originate in different neural tube domains, within boundaries of expression of a series of patterning genes which condition the diverse morphogenetic programme of each area. Although neuronal and astrocyte heterogeneity are widely accepted, and despite accumulating evidence for oligodendrocyte heterogeneity in vivo, oligodendrocytes in vitro are currently considered as a homogeneous cell population. The present investigation demonstrates that oligodendrocyte diversity can be detected in vitro and characterizes a novel morphological class of O4‐positive oligodendrocyte which is consistently identifiable in rat central nervous system cultures. These cells have a very characteristic epithelioid, unbranched and often lobulated morphology which enables their identification within 2 h of plating. lmmunostaining shows that this morphological type is sometimes positive for GD3, A2B5 and vimentin, and most of the time positive for Ranscht antibody, O1 and Rip but negative for glial fibrillary acidic protein, OX‐42, neuron‐specific enolase, nestin and erbB2. The apparent levels and/or distributions of (i) microtubules, (ii) surface glycolipids recognized by O4, O1 and Ranscht antibody, and (iii) the less specific marker carbonic anhydrase II, typically differ from those of nearby classical, branched oligodendrocytes. Cells with this epithelioid morphology also express myelin basic protein and O10 (a proteolipid protein epitope), both of which are markers for mature oligodendrocytes. Conversely, O4+/O1‐ cells with this membranous appearance were also seen. Although these atypical oligodendrocytes were most abundant in spinal cord cultures (representing >10% of the O4+ population), they were not exclusive to this region and occurred at a low frequency in neonatal optic nerve cultures.
Schwann Cells Modify Expression of Acetylcholinesterase and Butyrylcholinesterase at Rat Neuromuscular Junctions
Authors: Chapron J. , De La Porte S. , Delepine L. , Koenig J. 
Published: April 2006

AbstractUsing a monoclonal antibody (6.17) directed against a Schwann antigen, we have shown that Schwann cells synthesize a molecule implicated in a change of expression of synaptic cholinesterases, AChE and BChE, during muscle differentiation. In vitro, during synaptogenesis, the two enzymes are first present at developing synapses, and addition of Schwann cells to muscle‐neuron co‐cultures induces a disappearance of BChE, leaving only AChE activity as in the adult neuromuscular junction. This effect is inhibited by the 6.17 antibody. Thus, a molecule produced by Schwann cells is involved in the maturation of the neuromuscular synapse, in addition to the neuronal factors (CGRP, ARIA/heregulin, agrin), which are known to control the synthesis, maturation and accumulation of acetylcholine receptors and other synaptic components. In addition, in vivo, in the newborn rat, butyrylcholinesterase and acetylcholinesterase activities are initially present in equal amounts in the neural zone, but butyrylcholinesterase levels diminish sharply between 7 and 15 days after birth, the stage at which the synaptic Schwann cell membrane becomes juxtaposed with the muscle membrane.
Chondroitin/Dermatan Sulphate Promotes the Survival of Neurons from Rat Embryonic Neocortex
Authors: Kappler Joachim , Junghans Ulrich , Koops Antje , Stichel Christine C. , Hausser Heinz‐J. , Kresse Hans , Müller Hans Werner 
Published: April 2006

AbstractRecently we have shown that biglycan, a small chondroitin sulphate proteoglycan of the extracellular matrix, supports the survival of cultured neurons from the developing neocortex of embryonic day 15 rats. Here we investigate the structure‐function relationship of this neurotrophic proteoglycan and show that chondroitin/dermatan sulphate chains are the active moieties supporting survival. Heparin, a highly sulphated glucosaminoglycan, is less active than the galactosaminoglycans (chondroitin‐4‐sulphate, chondroitin‐6‐sulphate and dermatan sulphate), whereas hyaluronic acid, an unsulphated glucosaminoglycan, does not support neuron survival. Galactosaminoglycans must be in direct contact with neurons to cause survival. Experiments with elevated potassium concentrations and antagonists of voltage‐gated calcium channels exclude the involvement of membrane depolarization. However, genistein and an erbstatin analogue, which are inhibitors of tyrosine kinases with low specificity, abolished neuron survival in the presence of chondroitin/dermatan sulphate, whereas a selective inhibitor of neurotrophin receptor kinases (K252a) had no suppressive effect. Thus, yet unidentified tyrosine kinases are involved in the chondroitin/dermatan sulphate‐dependent survival of neocortical neurons. In the embryonic stages of rat neocortical development chondroitin sulphate is mainly located in layers I, V and VI and the subplate. Chondroitin sulphate expression is maintained after birth, extends up to cortical layer IV on postnatal day 7, and is down‐regulated until postnatal day 21 concomitant with the period of naturally occurring cell death. The latter observation is consistent with a putative role of chondroitin sulphate in the control of neuron survival during cortical histogenesis.
Choline Acetyltransferase, Glutamate Decarboxylase, Tyrosine Hydroxylase, Calcitonin Gene‐related Peptide and Opioid Peptides Coexist in Lateral Efferent Neurons of Rat and Guinea‐pig
Authors: Safieddine Saaid , Prior Ana Maria Soto , Eybalin Michel 
Published: April 2006

AbstractThe lateral efferent (olivocochlear) innervation of the cochlea originates in the brainstem lateral superior olive. It is likely to use acetylcholine, γ‐aminobutyric acid, dopamine and various neuropeptides as neurotransmitters and/or neuromodulators. In order to determine the different coexistence patterns of these molecules in lateral efferent perikarya, we have used double and triple immunofluorescence co‐localization techniques to colocalize choline acetyltransferase, glutamate decarboxylase, tyrosine hydroxylase, calcitonin gene‐related peptide and enkephalins in single sections of the lateral superior olive. We also used a non‐radoactive in situ hybridization technique onto serial sections of this nucleus to confirm the immunofluorescence co‐localization data at the mRNA level. Whatever the pair or triplet of primary antibodies tested was, a high ratio of coexistence was observed in the immunofluorescence experiments. In triple co‐localization experiments, 90–93% of the choline acetyltransferase‐like immunoreactive neurons were also immunoreactive to the two other antigens investigated. The in situ hybridization co‐localization data, based on the use of biotin‐labelled oligoprobes, qualitatively confirmed these immunofluorescence data. In conclusion, it can be postulated that acetylcholine, γ‐aminobutyric acid, dopamine, calcitonin gene‐related peptide, enkephalins and dynorphins (whose coexistence with choline acetyltransferase and enkephalins has been previously described immunocytochemically) coexist in lateral efferent neurons. Based on these results, it is tempting to propose the lateral efferent innervation as a useful model with which the functional implications of the coexistence of neurotransmitters/neuromodulators can be investigated in vivo.
Photoreceptor Cells of the Pike Pineal Organ as Cellular Circadian Oscillators
Authors: Bolliet Valérie , Bégay Valérie , Taragnat Catherine , Ravault Jean Paul , Collin Jean Pierre , Falcón Jack 
Published: April 2006

AbstractIn the pike pineal, the rhythm of melatonin (MEL) secretion is driven by a population of cellular circadian oscillators, synchronized by the 24 h light/dark (LD) cycle. Because the pineal photoreceptor contains both the input and output pathways of the clock, this cell is likely to be a cellular circadian system by itself. To support this idea, we have dissociated and cultured pike pineal cells as well as purified photoreceptors. In culture, the pineal cells reassociated in follicles, surrounded by collagen fibres. At the electron microscopic level, they appeared well preserved. Total cells consisted mainly of photoreceptors and glia. Purified cells corresponded exclusively to photoreceptors. Under LD, MEL production was rhythmic. Under constant darkness (DD), the rhythm was well sustained for at least six 24 h cycles (τ= 24/27 h) with 1 × 106 total cells/well or below; with 2 × 106 total cells/well, a strong damping occurred towards high levels as soon as after the second cycle. At the density of 0.5 × 106 cells/well, purified photoreceptors produced less MEL than an equivalent amount of total cells. However, the pattern of the oscillations was similar to that observed with 2 × 106 total cells, i.e. a damping occurred rapidly. Decreasing the density to 0.125 × 106 photoreceptors/well resulted in a loss of homogeneity among replicates. The production of melatonin by single photoreceptors was monitored by means of the reverse haemolytic plaque assay. Both under LD and under DD, the number of photoreceptors releasing melatonin was higher during the (subjective) dark than during the (subjective) light. The results provide strong support to the idea that the pike pineal photoreceptor is a cellular circadian system. Expression of the oscillations seemed to depend on several factors, including cell to cell contacts between photoreceptors. There is indication that also MEL and glia might be involved.
Localization of CAM II Kinase‐α, GAD, GluR2 and GABAA Receptor Subunit mRNAs in the Human Entorhinal Cortex
Authors: Longson Damien , Longson Carole M. , Jones Edward G. 
Published: April 2006

AbstractThe human entorhinal cortex (ERC) is an important relay between neocortical association areas and the hippocampus. Pathology in this area, including disturbances in its unique cytoarchitecture and alterations in neurotransmitter receptor binding, has been implicated in several neuropsychiatric disorders but details of the patterns of gene expression for molecules involved in the major neurotransmitter systems in this cortex have been lacking. We used in situ hybridization histochemistry to localize the mRNAs for several proteins which are involved in excitatory and inhibitory neurotransmission in the human ERC. Labelling of mRNA for a glutamate receptor subunit (GluR2) and for a marker of glutamatergic cortical neurons (alpha type II calcium/calmodulin‐dependent protein kinase) were distributed in a laminar manner which matched the cellular packing seen on the Nissl sections, with particularly high levels of labelling in the layer II (pre‐á) cell clusters characteristic of this cortex. Cells labelled for the mRNA of 67 kDa glutamic acid decarboxylase, the synthesizing enzyme of GABA, were distributed diffusely throughout all layers, not concentrated in the cell clusters, and were present in higher numbers in layer Ill. The labelling of mRNAs for the α1, β2 and γ2 subunits of the GABAA receptor, however, was distributed in a laminar pattern similar to that for GluR2 and CAM II kinase mRNAs, implying a high concentration of inhibitory synapses on the excitatory cells which express these mRNAs.