bluuebunny/crossref_metadata_2025_split huggingface dataset:
Properties of Cloned Rat α1A Calcium Channels Transiently Expressed in the COS‐7 Cell Line
Authors: Berrow N. S. , Brice N. L. , Tedder I. , Page K. M. , Dolphin A. C. 
Published: April 2006

AbstractThe rat brain α1A calcium channel clone has been expressed in COS‐7 cells together with the neuronal accessory subunits p1b and α2‐δ. From reverse transcriptase polymerase chain reaction (RT‐PCR), immunocytochemistry and electrophysiology experiments, we have obtained no evidence that these cells contain any endogenous calcium channels. Transfected cells were identified by co‐expression of a cDNA for the reporter Green Fluorescent Protein. From immunocytochemical evidence, a high degree of co‐expression was obtained between Green Fluorescent Protein and individual calcium channel subunits. When all three calcium channel subunits (α1, α2‐δ and β1b) were co‐expressed, evidence was obtained that all subunits were present at the cell membrane. Voltage‐dependent calcium currents were observed between 24 and 72 h after transfection with the three calcium channel subunits. The current density for the combination α1A/α/β1ba24IPlb was 4.19 ± 0.69 pA.pF‐1 and the current produced was slowly inactivating. The time constant of inactivation of the maximum IBa was 332 ± 46 ms (n = 5). The voltage‐dependence of activation and steady‐state inactivation had voltages of half activation and inactivation of 9.5 ± 2.5 mV and ‐30.4 ± 1.5 mV respectively, and there was little overlap between the two curves. The α1A current was completely blocked by 100 μM Cd2+ and was also blocked by ω‐conotoxin MVIIC (500 nM). Dose‐inhibition curves and analysis of kon and kfor for ω‐agatoxin IVA both revealed apparent KD values of approximately 11 nM for α1A currents, with a kD of 7.8 × 104 M‐1s‐1. The results suggest that α1A expressed in these cells has some resemblance to the P type component of calcium current observed in native neurons, although it shows a somewhat greater degree of inactivation than native P current, more similar to the Q type current component. It also has an affinity for ω‐agatoxin IVA 2–5 fold lower than reported for P current, but approximately 9‐fold higher than reported for Q current.
Cable Properties of Dendrites in Hippocampal Neurons of the Rat Mapped by a Voltage‐sensitive Dye
Authors: Meyer Elisabeth , Müller Carsten O. , Fromherz Peter 
Published: April 2006

AbstractDendrites of pyramidal neurons from embryonic rat hippocampus are investigated in culture using a voltage‐sensitive fluorescent dye. The electrical response to somatic stimulation is observed as a time‐resolved map with a resolution of 0.9 μM at a time constant of 0.4 ms without signal averaging. The data are interpreted in terms of a tapering cable with Hodgkin‐Huxley parametrization. The spread of short hyperpolarizing transients is damped by capacitive shunting. The invasion of an action potential is boosted by voltage‐gated conductances of a low density. No irregularity is observed at a bifurcation. The passive cable parameters of internal resistance and membrane resistance at resting voltage are Ri= 300 ωcm and Rm= 40 kωcm2 respectively, at a maximum sodium conductance of ˜4.4 mS/cm2. The electrotonic length constant and the dynamic length constant at 1 kHz are 580 and 90 μm respectively. These results are compatible with electrophysiological data of dendrites in slices of adult hippocampus and with optical data of narrow processes of leech neurons in culture. The functional implications of boosting an action potential by voltage‐gated channels of low density are considered.
Effects of Noradrenaline on Frequency Tuning of Rat Auditory Cortex Neurons
Authors: Manunta Yves , Edeline Jean‐Marc 
Published: April 2006

AbstractThe selectivity of rat auditory cortex neurons for pure tone frequency was studied during and after ionophoretic application (5–40 nA) of noradrenaline in urethane‐anaesthetized rats. The dominant effect induced by noradrenaline was a significant decrease in spontaneous (93/268 cells) and evoked activity (1331268 cells) which outlasted the application. In the whole population of cells (n= 268) the signal‐to‐noise ratio, computed using as the signal either the mean evoked response or the response at the best frequency, was unchanged during noradrenaline application. It was significantly increased only for cells showing significantly decreased spontaneous activity, and was significantly decreased for cells showing increased spontaneous activity. Frequency selectivity was significantly increased for the whole population during and after noradrenaline application. It was also significantly increased for cells showing significantly decreased evoked activity, and was significantly decreased for cells showing increased evoked activity. The noradrenaline‐induced inhibition was not blocked by propranolol (β antagonist); it was blocked by prazosin (α1 antagonist) and partly mimicked by phenylephrine (α1 agonist). GABA, which also inhibited spontaneous and evoked activity, slightly increased the signal‐to‐noise ratio and significant increased frequency selectivity. However, when noradrenaline was ejected in the presence of bicuculline at doses that were able to block GABAergic inhibition, the inhibitory effects of noradrenaline on spontaneous and evoked activity were still observed. The possible function of noradrenaline‐induced inhibitions in sensory cortices is briefly discussed.
Neonatal γ‐Ray Irradiation Impairs Learning and Memory of an Olfactory Associative Task in Adult Rats
Authors: Chaillan F. A. , Devigne C. , Diabira D. , Khrestchatisky M. , Roman F. S. , Ben‐Ari Y. , Soumireu‐Mourat B. 
Published: April 2006

AbstractAdult neonatally γ‐irradiated rats were compared with control animals in a non‐spatial olfactory associative task using two different procedures. Irradiation induced a clear reduction in the total mean area of the olfactory bulbs and hippocampus but not of the orbital prefrontal cortex, diagonal band and cell layers of the entorhinal and piriform cortex. The γ‐irradiation affected the granule cells of the olfactory bulbs and differentially altered the cell layers of the subfields of the ammonic fields and the dorsal and ventral blades of the dentate gyrus. In the CA1 ammonic field, dorsal and ventral blades of the dentate gyrus, the cellular loss was significant in comparison with control adult rats. The behavioural data indicated that irradiated rats were deeply disturbed in learning the odour‐reward association, and substantially impaired in a reversal experiment, but not in the discrimination of the odours per se. The cellular loss in the olfactory bulbs, in the CA1 and in the ventral blade of the gyrus dentatus was positively correlated with the deficit in behavioural performance. The data support the findings that the hippocampal system participates in the odour‐reward associations and facilitates the long‐term storage of associations after learning is achieved in this olfactory associative task.
Protection Against Oxidative Stress‐induced Neuronal Cell Death‐A Novel Role for RU486
Authors: Behl Christian , Trapp Thorsten , Skutella Thomas , Holsboer Florian 
Published: April 2006

AbstractFree radicals and oxidative stress‐induced neuronal cell death have been implicated in a variety of neurological disorders. Therefore, neuroprotection is of primary interest in basic and preclinical neuroscience. Here it is shown that RU486 (mifepristone), a potent antagonist of progesterone and glucocorticoid receptors, protects rat primary hippocampal neurons, clonal mouse hippocampal cells and organotypic hippocampal slice cultures against oxidative stress‐induced neuronal cell death. 10‐5 M RU486 prevents intracellular peroxide accumulation and cell death induced by amyloid β protein, hydrogen peroxide and glutamate, neurotoxins that have been implicated in certain neurodegenerative disorders, including Alzheimer's disease. RU486 has a significant protective effect that is independent of the presence and activation of glucocorticoid or progesterone receptors. The neuroprotective activity of this well‐studied drug may have an impact on therapeutic interventions for neurodegenerative conditions which involve peroxidation processes. such as stroke and Alzheimer's disease.
Evidence for the Involvement of the Mammillary Bodies and Cingulum Bundle in Allocentric Spatial Processing by Rats
Authors: Neave N. , Nagle S. , Aggleton J. P. 
Published: April 2006

AbstractComparisons were made between the behavioural effects of lesions in three inter‐related limbic structures: the mammillary bodies, the fornix and the cingulum bundle/cingulate cortex. Cytotoxic lesions of the mammillary nuclei produced a marked deficit on reinforced T‐maze alternation, but performance gradually improved with practice. Subsequent tests in a cross‐maze and a radial‐arm maze showed that the animals with mammillary body lesions failed to use allocentric cues, but were able to perform normally in an egocentric discrimination. Three groups of rats with different patterns of either crossed or unilateral radio frequency lesions of the cingulate region were given the same tasks. The profile of results indicated that disruption of those fibres in the cingulum bundle connecting the anterior thalamic nuclei with the hippocampal/retrohippocampal region was responsible for the observed impairments to T‐maze alternation and radial‐arm maze performance. There was also evidence that disconnection of frontal connections in the cingulum bundle might affect perseverative behaviour, but not allocentric processing. The results add support to the notion of a functional circuit that involves projections from the hippocampus to the mammillary bodies and anterior thalamic nuclei, and from there back to hippocampal/ retrohippocampal regions via the cingulum bundle. This circuit appears to be vital for normal allocentric processing.
Lymphocyte Recruitment Following Spinal Cord Injury in Mice is Altered by Prior Viral Exposure
Authors: Schnell Lisa , Schneider Regula , Berman Monique A. , Perry V. Hugh , Schwab Martin E. 
Published: April 2006

AbstractThe inflammatory response induced by mechanical lesion of the spinal cord is known to include the recruitment of neutrophils and macrophages, while the involvement of lymphocytes has been largely ignored. We have studied the pattern of lymphocyte recruitment following partial transection of the mouse spinal cord. Using immunohistochemical techniques, all three types of lymphocytes (CD4‐positive T‐cells, CD8‐ positive T‐cells and B‐cells) were found in the vicinity of the lesion site within hours and persisted for up to 7 days. There was a predominance of B‐lymphocytes during the first 3 days. A second, late phase of cell infiltration, dominated by CD8‐positive T‐lymphocytes, occurred in mice that had been raised in a conventional breeding unit and had acquired antibody titres to a common murine virus (mouse hepatitis virus). In contrast, mice kept in specific pathogen‐free facilities did not show this late‐phase response. These findings suggest a possible role for lymphocytes in secondary tissue loss, local demyelination, scar formation, cytokine‐mediated inflammatory responses or trophic processes. They also provide evidence that a virus infection can significantly enhance the reaction of T‐cells to a spinal cord lesion.
Dopaminergic Phenotype Induced by Oestrogens in a Human Neuroblastoma Cell Line
Authors: Agrati P. , Ma Z. Q. , Patrone C. , Picotti G. B. , Pellicciari C. , Bondiolotti G. , Bottone M. G. , Maggi A. 
Published: April 2006

AbstractOestrogens are the key factor in the sexual differentiation of the mammalian brain and play an important role in the activity of selected areas of the mature brain. To pursue the study of oestrogen action on neural cells at the molecular level, we developed a human neuroblastoma cell line (SK‐ER3) expressing the oestrogen receptor (ER). Treatment of these cells with 17β‐oestradiol causes growth arrest and morphological and biochemical differentiation. The aim of the present study was to investigate whether oestrogen‐differentiated SK‐ER3 neuroblastoma cells acquire the ability to synthesize a specific neurotransmitter and whether the growth arrest previously reported can be ascribed to the blockage of the cells at a specific stage of the cell cycle. The results presented here indicate that oestrogens induce accumulation of SK‐ER3 cells in the GO phase of the cell cycle, underscoring the acquisition of a mature neural phenotype upon hormonal treatment. Most importantly, we show that in the differentiated cells the content of tyrosine hydroxylase and Na+‐dependent dopamine uptake is significantly augmented, proving that the oestrogen‐differentiated SK‐ER3 cells can synthesize and store a specific neurotransmitter. In addition, we prove that the dopamine accumulated in differentiated SK‐ER3 cells can be released. These studies therefore suggest that oestrogen treatment results in the acquisition of a fully functional dopaminergic phenotype of SK‐ER3 cells. Ample evidence shows a link between dopaminergic neurons and oestrogen activity in hypothalamic and non‐hypothalamic areas of the mammalian brain. Our study indicates that oestrogens might play a primary role in committing undifferentiated neuroblasts towards the dopaminergic phenotype.
Interaction Between Neurons in Different Laminae of the Dorsal Horn of the Spinal Cord. A Correlation Study in Normal and Neuropathic Rats
Authors: Biella Gabriele , Riva Lilette , Sotgiu Maria Luisa 
Published: April 2006

AbstractSimultaneous recordings of 135 pairs of units, located respectively in the superficial (I‐110) and deep (V) laminae of the dorsal horn of the lumbar spinal cord of anaesthetized and paralysed animals, were performed both from normal (62 pairs) and from peripherally injured (chronically constricted sciatic nerve) rats (73 pairs). In each pair, one neuron was classified as nociceptive, responding only to noxious stimuli, and the other as a wide dynamic range neuron, responding to both non‐noxious and noxious stimuli. To understand if some interaction was present between diverse neurons modulated by noxious inputs, we used cross‐correlation techniques. The responses of simultaneously recorded pairs of units to suprathreshold (5 mA, 0.5 ms) electrical stimuli were used. A clearly delayed peak in the cross‐correlograms of recordings from normal animals was present, indicating connectivity of superficial and deep‐layer cells. This feature was not present in the cross‐correlograms obtained from nerve‐injured animals. Even if a specific pathway cannot be explicitly assigned to support these functional results, an overall connection between superficial and deep layers of the spinal cord is suggested. These connections are supposed to be either inactive or rearranged in the nerve‐injured rats, thus suppressing a well timed coordinated connectivity. This anomaly could underlie a reduced degree of functional coherence in the modulation of nociceptive spinal inputs in cases of chronic pain.
Magnetoencephalography May Help to Improve Functional MRI Brain Mapping
Authors: Beisteiner R. , Erdler M. , Teichtmeister C. , Diemling M. , Moser E. , Edward V. , Deecke L. 
Published: April 2006

AbstractThe validity of functional magnetic resonance imaging (FMRI) brain maps with respect to the sites of neuronal activation is still unknown. One source of localization error may be pixels with large signal amplitudes, since such pixels may be expected to overlie large vessels, running remote from the centre of neuronal activation. In this study, magnetoencephalography was used to determine the centre of neuronal activation in a simple finger tapping task. The localization accuracy of conventional FMRI depending on FMRI signal enhancement was investigated relative to the magnetoencephalography reference. The results show a deterioration of FMRI localization with increasing signal amplitude related to increased contributions from large vessels. We conclude that FMRI data analysis should exclude large signal amplitudes and that magnetoencephalography may help to improve FMRI brain mapping results in a multimethod approach.
The Perceptual Grouping Criterion of Colinearity is Reflected by Anisotropies of Connections in the Primary Visual Cortex
Authors: Schmidt Kerstin E. , Goebel Rainer , Löwel Siegrid , Singer Wolf 
Published: April 2006

AbstractAn important step in the processing of visual patterns is the segmentation of the retinal image. Neuronal responses evoked by the contours of individual objects need to be identified and associated for further joint processing. These grouping operations are based on a number of Gestalt criteria. Here we report that connections in the visual cortex of the cat exhibit a highly significant anisotropy, preferentially linking neurons activated by contours that have similar orientation and are aligned colinearly. These anatomical data suggest a close relation between the perceptual grouping criterion of colinearity and the topology of tangential intracortical connections. We propose that tangential intracortical connections support perceptual grouping by modulating the saliency of distributed cortical responses in a context‐dependent way. The present data are compatible with the hypothesis that the criteria for this grouping operation are determined by the architecture of the tangential connections.
Visual Control of Hand‐reaching Movement: Activity in Parietal Area 7m
Authors: Ferraina S. , Garasto M. R. , Battaglia‐Mayer A. , Ferraresi P. , Johnson P. B. , Lacquaniti F. , Carniniti R. 
Published: April 2006

AbstractThe activity of single neurons was studied in parietal area 7m while monkeys performed an instructed‐delay reaching task to visual targets under normal light conditions and in darkness. The task was aimed at assessing the influence of vision of hand position on the neural activity of 7m related either to static posture and movement of the hand or to eye position in the orbit. The results show the existence of preparatory, movement‐related and postural activity for the control of reaching, all of which are strongly modulated by vision. The activity of many 7m neurons, otherwise insensitive to pure visual stimuli, seems to reflect complex interactions between gaze angle and hand position in the visual field.
Cocaine‐induced Increase in Cortical Acetylcholine Release: Interaction with the Hypothalamo—Pituitary—Adrenal Axis
Authors: Day Jamie C. , Piazza Pier Vincenzo , Le Moal Michel , Maccari Stefania 
Published: April 2006

AbstractAn influence on drug‐taking behaviours of the stress‐related hypothalamo‐pituitary‐adrenal (HPA) axis and its final hormonal mediator, corticosterone, has previously been demonstrated. A role for cortically projecting cholinergic neurons in these behaviours can also be proposed. The experiments presented here examine the effect of the drug of abuse cocaine (15 mg/kg) on the release of acetylcholine (ACh) in the cortex of freely moving rats, using the technique of in vivo microdialysis. To assess a possible modulatory influence of the HPA axis via its final hormonal mediator corticosterone, the cocaine‐induced effect on cortical ACh release in intact rats was compared to that in adrenalectomized (ADX) rats, which thus lacked their endogenous source of corticosterone, and in ADX rats in which the cocaine‐induced corticosterone peak and/or the basal circadian concentrations of serum corticosterone were simulated by replacement treatments. The results reported here demonstrate that cortical ACh release is greatly increased by cocaine in intact rats; ADX prolongs the return to basal levels of cortical ACh, and the chronic replacement of circadian levels of corticosterone normalizes this effect. In contrast, during the plateau period of cocaine‐induced increased cortical ACh release, where no effect of ADX is evident, rats with chronic replacement of corticosterone show an attenuated cocaine‐induced cortical ACh release, and the acute replacement of the cocaine‐induced corticosterone secretion further attenuates this response. These results demonstrate that cocaine stimulates cortically projecting cholinergic neurons, and that the HPA hormone corticosterone modulates this interaction in a complex manner which merits further investigation.
Relative Changes in Regional Cerebral Blood Flow During Spinal Cord Stimulation in Patients with Refractory Angina Pectoris
Authors: Hautvast Raymond W. M. , Ter Horst Gert J. , DeJong Bauke M. , DeJongste Mike J. L. , Blanksma Paul K. , Paans Anne M. J. , Korf Jakob 
Published: April 2006

AbstractSpinal cord stimulation applied at thoracic level 1 (T1) has a neurally mediated anti‐anginal effect based on anti‐ischaemic action in the myocardium. Positron emission tomography was used to study which higher brain centres are influenced by spinal cord stimulation. Nine patients with a spinal cord stimulator for angina pectoris were studied using H215O as a flow tracer. Relative changes in regional cerebral blood flow related to stimulation compared with non‐stimulation were assessed and analysed using the method of statistical parametric mapping. Increased regional cerebral blood flow was observed in the left ventrolateral periaqueductal grey, the medial prefrontal cortex [Brodmann area (BA) 9/10], the dorsomedial thalamus bilaterally, the left medial temporal gyrus (BA 21), the left pulvinar of the thalamus, bilaterally in the posterior caudate nucleus, and the posterior cingulate cortex (BA 30). Relative decreases in rCBF were noticed bilaterally in the insular cortex (BA 20/21 and BA 38), the right inferior temporal gyrus (BA 19/37), the right inferior frontal gyrus (BA 45), the left inferior parietal lobulus (BA 40), the medial temporal gyrus (BA 39) and the right anterior cingulate cortex (BA 24). It is concluded that spinal cord stimulation used as an additional treatment for angina applied at TI modulates regional cerebral blood flow in brain areas known to be associated with nociception and in areas associated with cardiovascular control.
α7 and α8 Nicotinic Receptor Subtypes Immunopurified from Chick Retina have Different Immunological, Pharmacological and Functional Properties
Authors: Gotti Cecilia , Moretti Milena , Maggi Roberto , Longhi Renato , Hanke Wolfang , Klinke Nicole , Clementi Francesco 
Published: April 2006

AbstractNicotinic receptors are present in the chick retina, but their structure and functional characteristics are still unclear. Using anti‐α7 and anti‐α8 subunit‐specific antibodies, we immunopurified the α7 and α8 subtypes of chick retina neuronal nicotinic receptors. When analysed by sodium dodecyl sulphate‐polyacrylamide gel electrophoresis, the two purified subtypes consistently showed a similar peptide composition characterized by the presence of two major peptides of Mr 58 ± 1 and 54 ± 1 kDa, and two minor peptides of 67 and 61 ± 1 kDa. In the α7 subtype, the 58 kDa peptide was recognized by anti‐α7 but not by anti‐α8 antibodies; in the α8 subtype, the 58 kDa peptide was recognized only by anti‐α8 antibodies. The α7 subtype had a single class of [125]a‐bungarotoxin binding sites with a KD value of 1.2 nM, whereas the purified α8 subtype had two classes of binding sites, one with a KD of 5.5 nM and the other with very high affinity (KD 52 pM), but present in only 8% of the receptors. Competition binding experiments also showed the presence on the α8 subtype of highand low‐affinity classes of binding sites; the affinity for cholinergic drugs of the former was greater than that of the single class present on the α7 subtype. When reconstituted in planar lipid bilayers, both subtypes formed ligand‐gated cation channels with major conductance levels of 42 and 52 pS but with different lifetimes; the two channels were activated by agonists and blocked by d‐tubocurarine and the glycinergic antagonist strychnine. In line with the binding data, the reconstituted α8 subtype had greater agonist sensitivity than the α7 subtype.