bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular Identification of the 62 kd Form of Glutamic Acid Decarboxylase from the Mouse
Authors: Katarova Z. , Szabo G. , Mugnaini E. , Greenspan R. J. 
Published: April 2006

AbstractA series of overlapping clones coding for L‐glutamic acid decarboxylase was purified from a mouse brain cDNA library, the longest of which contains a 1869 bp open reading frame and 913 bp of non‐coding sequence. By comparison with the corresponding sequences from the mouse genome, it was determined that the first methionine in the longest cDNA represents the initiation codon. Expression of this cDNA in eukaryotic cells produces a 62 kd protein that is recognized by antiserum against rat GAD and which displays GAD activity commensurate with the amount of protein produced. Antibodies raised against the purified product of this cDNA recognize a 62 kd protein from mouse brain on immunoblots, specifically stain GABA‐ergic neurons in brain sections, and are capable of immunoprecipitating most GAD activity from mouse brain extracts. These results provide the first definitive identification of a cDNA coding for the larger of two forms of GAD in mouse brain, and suggest that the two forms are closely related.
Auditory Neurons with Transitory Axons to Visual Areas Form Short Permanent Projections
Authors: Clarke Stephanie , Innocenti Giorgio M. 
Published: April 2006

AbstractThe kitten's auditory cortex (including the first and second auditory fields Al and All) is known to send transient axons to either ipsi‐ or contralateral visual areas 17 and 18. By the end of the first postnatal month the transitory axons, but not their neurons of origin, are eliminated. Here we investigated where these neurons project after the elimination of the transitory axon. Eighteen kittens received early (postnatal day (pd) 2–5) injections of long lasting retrograde fluorescent traces in visual areas 17 and 18 and late (pd 35–64) injections of other retrograde fluorescent tracers in either hemisphere, mostly in areas known to receive projections from Al and All in the adult cat. The middle ectosylvian gyrus was analysed for double‐labelled neurons in the region corresponding approximately to Al and All. Late injections in the contralateral (to the analysed Al, All) hemisphere including all of the known auditory areas, as well as some visual and ‘association’ areas, did not relabel neurons which had had transient projections to either ipsi‐ or contralateral visual areas 17–18. Thus, Al and All neurons after eliminating their transient juvenile projections to visual areas 17 and 18 do not project to the other hemisphere. In contrast, relabelling was obtained with late injections in several locations in the ipsilateral hemisphere; it was expressed as per cent of the population labelled by the early injections. Few neurons (0–2.5%) were relabelled by large injections in the caudal part of the posterior ectosylvian gyrus and the adjacent posterior suprasylvian sulcus (areas DP, P, VP). Multiple injections in the middle ectosylvian gyrus relabelled a considerably larger percentage of neurons (13%). Single small injections in the middle ectosylvian gyrus (areas Al, All), the caudal part of the anterior ectosylvian gyrus and the rostral part of the posterior ectosylvian gyrus relabelled 3.1–7.0% of neurons. These neurons were generally near (< 2.0 mm) the outer border of the late injection sites. Neurons with transient projections to ipsi‐ or contralateral visual areas 17 and 18 were relabelled in similar proportions by late injections at any given location. Thus, Al or All neurons which send a transitory axon to ipsi‐ or contralateral visual areas 17 and 18 are most likely to form short permanent cortical connections. In that respect, they are similar to medial area 17 neurons that form transitory callosal axons and short permanent axons to ipsilateral visual areas 17 and 18.
Transient Sensitivity of Rat Cerebellar Purkinje Cells to N‐methyl‐D‐aspartate during Development. A Voltage Clamp Study in in vitro Slices
Authors: Krupa M. , Crepel F. 
Published: April 2006

Abstract In vitro sagittal slices of immature rat cerebellum were used to study the development of the sensitivity of Purkinje cells (PC) to L‐glutamate (Glu) and N‐methyl‐D‐aspartate (NMDA). In 8‐day‐old animals, all PCs recorded in magnesium‐free medium responded to iontophoretic applications of both agonists by transient and dose dependent inward currents which, in both cases, were heavily contaminated by a Glu and NMDA‐induced synaptic noise. When 5 × 10−6 M tetrodotoxin (TTX) was added to the perfusing medium, this evoked synaptic noise was completely abolished in most cells whereas clear‐cut inward currents induced in PCs by Glu and NMDA applications on their dendrites were still visible. These responses were selectively antagonized by the non‐NMDA glutamate receptor antagonist 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione (CNQX) and by the NMDA receptor antagonist D‐2‐aminophosphono‐5‐valeric acid (2APV) respectively. Excitatory responses induced by aspartate in 8– 10‐day‐old PCs were also markedly antagonized by CNQX. At this stage, the sensitivity of PCs to NMDA was about one order of magnitude less than that to Glu. In 15–20‐day‐old animals, all PCs were still responsive to Glu whereas only 70% of them were still excited by NMDA in the presence of TTX in the bath. Furthermore, the sensitivity of PCs to Glu was higher than at 8 days of age, whereas that to NMDA was significantly lower, even when considering only those cells which still responded to this agonist. This trend was still accentuated later on since at 2 months of age, only 25% of PCs were excited by NMDA whereas their sensitivity to Glu was similar to that observed in 15–20‐day‐old animals. Therefore, the present results are fully consistent with the view that PCs have a transient expression of NMDA receptors during development.
Time‐related Changes in Basal Phosphoinositide Turnover after Induction of Long‐term Potentiation in the Dentate Gyrus are Blocked by Commissural Stimulation
Authors: Clements M. P. , Errington M. L. , Bliss T. V. P. , Lynch M. A. 
Published: April 2006

AbstractWe have examined basal phosphoinositide turnover in synaptosomes obtained from the dentate gyrus of anaesthetized rats in which long‐term potentiation was induced unilaterally in perforant path‐granule cell synapses. Relative to the unpotentiated side. [3H]myo‐inositol labelling of inositol phosphates was significantly enhanced 45 min and 3 h after induction of long‐term potentiation, but reduced after 2.5 min. Similarly, [14C]arachidonic acid labelling of 1,2‐diacylglycerol was increased 45 min and 3 h after induction of long‐term potentiation, but reduced after 2.5 min. In a second series of experiments, induction of long‐term potentiation was blocked by stimulation of the commissural projection to granule cells. In synaptosomes prepared from this tissue, there was no difference in phosphoinositide turnover between tetanized and control sides at any of the three post‐tetanic intervals. We conclude that in the dentate gyrus, long‐term potentiation is associated with an increase in phosphoinositide turnover which is established between 2.5 min and 45 min post‐tetanus and which persists for at least 3 h.
Nerve Growth Factor Regulates Expression of the Nerve Growth Factor Receptor Gene in Adult Sensory Neurons
Authors: Lindsay R. M. , Shooter E. M. , Radeke M. J. , Misko T. P. , Dechant G. , Thoenen H. , Lindholm D. 
Published: April 2006

AbstractSensory neurons of the adult rat dorsal root ganglion (DRG) can be maintained in culture in the absence of nerve growth factor (NGF). We have thus used dissociated cultures of these neurons to study effects of NGF on the regulation of expression of mRNA encoding the nerve growth factor receptor (NGF‐R). In the absence of NGF, levels of NGF‐R mRNA remained constant for 7 days in cultures of adult rat DRG neurons. In the presence of NGF, NGF‐R mRNA levels rose two ‐ three‐fold after 2 days, reaching plateau levels (five ‐ six‐fold elevation) after 5 days. This NGF‐induced up‐regulation could be demonstrated even after prior NGF‐deprivation for 3–4 days. NGF had no effect upon NGF‐R mRNA levels in DRG non‐neuronal cells. Epidermal growth factor (EGF), fibroblast growth factor (FGF) and ciliary neurotrophic factor (CNTF) were without effect on NGF‐R mRNA levels, but 8‐bromo‐cAMP decreased NGF‐R mRNA levels by 65% after 2 days. NGF also induced a rapid (30 min) rise in expression of c‐fos in DRG neurons, but not in non‐neuronal cells. Our results suggest that endogenous levels of NGF may regulate the expression of NGF‐R in vivo.
Evidence that the Rate of Wallerian Degeneration is Controlled by a Single Autosomal Dominant Gene
Authors: Perry V. H. , Lunn E. R. , Brown M. C. , Cahusac S. , Gordon S. 
Published: April 2006

AbstractIn a substrain of C57BL mice, C57BL/Ola, Wallerian degeneration in the distal segment of the severed sciatic nerve is extremely slow when compared to other mice. Despite this very slow degeneration in the distal segment regeneration of the motor nerves is not impaired. From suitable genetic outcrosses and backcrosses, the authors provide evidence that the rate of Wallerian degeneration in this strain is controlled by a single autosomal gene product. The authors have also shown that the rate of degeneration, in C57BL/Ola mice, is influenced by the environment in which the animals were bred and housed. Wallerian degeneration in the sciatic nerves of mice raised in isolators is slower than in those raised in a conventional animal house. This strain of mouse may prove to be of value in the understanding of nerve degeneration and regeneration.
Monoaminergic and Peptidergic Innervation of the Intermedio‐Lateral Horn of the Spinal Cord
Authors: Fuxe K. , Tinner B. , Bjelke B. , Agnati L. F. , Verhofstad A. , Steinbusch H. G. W. , Goldstein M. , Hersh L. , Kalia M. 
Published: April 2006

AbstractIn the rat the monoamine and neuropeptide innervation of the sympathetic visceral nuclei has been analysed using retrograde tracing and single and double immunolabelling procedures. When combined with tyrosine hydroxylase (TH), 5‐hydroxytryptamine (5‐HT) and enkephalin (ENK) immunocytochemistry, somata and dendrites of many preganglionic sympathetic neurons projecting to the coeliac ganglion visualized by retrograde tracing are found in close association with strands and plexa of strongly TH, 5‐HT or ENK immunoreactive (IR) nerve terminals, while others have only a minor association with strong TH, 5‐HT and ENK immunoreactivities, suggesting that a differential control of preganglionic sympathetic neurons is possible. Experiments with double immunolabelling procedures give further support to a direct innervation of preganglionic sympathetic neurons by TH, 5‐HT and ENK IR nerve terminals. In conclusion, the present results open up the possibility for differential regulation of the preganglionic sympathetic neurons according to the Sherringtonian concept of spatial occlusion and facilitation in a pool of motoneurons.
Activation of a K‐252b‐Sensitive Protein Kinase is Necessary for a Post‐Synaptic Phase of Long‐Term Potentiation in Area CA1 of Rat Hippocampus
Authors: Reymann K. G. , Davies S. N. , Matthies H. , Kase H. , Collingridge G. L. 
Published: April 2006

AbstractK‐252b, a potent inhibitor of protein kinases blocked a late phase of long‐term potentiation (LTP) in area CA1 of rat hippocampal slices, resulting in decremental LTP. It also prevented the slowly developing increase in sensitivity of CA1 neurons to iontophoretically administered α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid (AMPA) which was seen in control slices that exhibit nondecremental LTP. However, K‐252b applied 60–180 min after the induction of LTP had no effect on the potentiated synaptic and AMPA‐induced responses. A K‐252b‐sensitive protein kinase may therefore be involved in a slowly developing postsynaptic component of LTP.
Topographical and Synaptic Organization of the GABA‐Containing Pallidosubthalamic Projection in the Rat
Authors: Smith Y. , Bolam J. P. , von Krosigk M. 
Published: April 2006

AbstractThe anterograde transport of Phaseolus vulgaris‐leucoagglutinin (PHA‐L) was combined with postembedding immunocytochemistry for gamma‐aminobutyric acid (GABA) to study the topography, the synaptic organization and the neurotransmitter content of the pallidosubthalamic projection in the rat. After injections of PHA‐L in different parts of the globus pallidus a rich plexus of anterogradely labelled fibres and terminals was found in the ipsilateral subthalamic nucleus. The immunoreactive elements were distributed according to a mediolateral and rostrocaudal topography. Injections of PHA‐L restricted to the lateral two‐thirds of the globus pallidus gave rise to a massive anterograde labelling confined to the lateral half of the subthalamic nucleus. On the other hand, injections of PHA‐L strictly confined to the medial part of the globus pallidus resulted in anterograde labelling that occupied the ventromedial pole of the subthalamic nucleus. In some cases a few retrogradely labelled cells were found in the subthalamic nucleus after PHA‐L injections in the globus pallidus. The perikarya and the primary dendrites of these labelled cells were sometimes surrounded by anterogradely labelled terminals suggesting a close reciprocal connection between the globus pallidus and the subthalamic nucleus. Electron microscopic analysis of the PHA‐L‐labelled terminals revealed that they contain many mitochondria, numerous small round or slightly pleomorphic vesicles and occasionally one or two large dense core vesicles. They form symmetrical synaptic contacts predominantly with the proximal dendrites (39%) and less frequently with the perikarya (31%) and the distal dendrites (30%) of the subthalamic cells. Quantitative measurements showed that the pallidosubthalamic varicosities have a diameter ranging from 0.7 to 4.5 μm and a mean cross‐sectional area of 0.79 ± 0.26 μm2 (Mean ± SD). Postembedding immunocytochemistry for GABA revealed that the PHA‐L‐immunoreactive pallidosubthalamic axon terminals display GABA immunoreactivity. The results of our study demonstrate that the pallidosubthalamic projection is organized according to a mediolateral and rostrocaudal topography and that the proximal dendrites of the subthalamic cells are the major targets of the GABA‐immunoreactive pallidosubthalamic terminals. This suggests that the globus pallidus exerts a powerful control over the subthalamic cells through an inhibitory GABAergic pathway.
Long‐term Activation of Phosphoinositide Turnover Associated with Increased Release of Amino Acids in the Dentate Gyrus and Hippocampus Following Classical Conditioning in the Rat
Authors: Laroche S. , Negro C. Redini‐Del , Clements M. P. , Lynch M. A. 
Published: April 2006

AbstractThe release of amino acids and the hydrolysis of inositol phospholipids were examined in parallel in three hippocampal areas following classical conditioning. Paired or unpaired tone(CS) ‐ shock(US) presentations were given to animals engaged in a previously acquired food‐motivated lever‐pressing task. Conditioned suppression of lever‐pressing was the behavioural measure of conditioning. Twenty‐four hours after the last conditioning session, the dentate gyrus and areas CA3 and CA1 of the hippocampus were removed bilaterally from conditioned and pseudoconditioned animals, and slices cut and stored in liquid nitrogen for subsequent analysis. Crude synaptosomal pellets were prepared to investigate: (i) potassium‐stimulated release of preloaded [3H]glutamate and [14C]aspartate in the presence and absence of extracellular Ca2+; (ii) [3H]inositol labelling of phosphoinositides and inositol phosphates; and (iii) [14C]arachidonic acid labelling of 1,2‐diacylglycerol (1,2‐DG). Potassium‐stimulated, Ca2+‐dependent release of [3H]glutamate in synaptosomes prepared from the dentate gyrus and area CA3 was significantly greater in conditioned animals than in pseudoconditioned animals. In area CA1, K+‐stimulated, Ca2+‐dependent release of [14C]aspartate was significantly increased in conditioned animals. These results confirm in synaptosomes, and extend to a period of 24 h our previous report of an increased release of transmitter in the dentate gyrus and hippocampus associated with classical conditioning. In parallel with the increased release of amino acids, learning was associated with a significant increase in labelling of phosphoinositides and inositol phosphates by [3H]inositol and a significant increase in labelling of 1,2‐DG by [14C]arachidonic acid in the three hippocampal areas examined. It is suggested that a long‐lasting presynaptic activation of inositol lipid metabolism may contribute to the learning‐dependent increase in the capacity of hippocampal terminals to release transmitter and hence to the maintenance of a neurochemical trace which may, at least in part, underlie lasting changes in synaptic function built up during associative learning.
Memory for Places and the Region of the Mamillary Bodies in Rats
Authors: Saravis S. , Sziklas V. , Petrides M. 
Published: April 2006

AbstractRats with extensive lesions of the mamillary bodies and the immediately adjoining areas exhibited a severe impairment on two spatial memory tasks. In the first task, the animals had to retrieve food from each one of eight separate locations within the daily test session. In the second task, the animals were allowed to visit a particular location and retrieve food from it and, after a variable delay, they had to select between returning to the location they had already visited and a new location that now contained the food. Rats with lesions of the mamillary region were able to perform the task with minimal delay, but their performance was impaired as the delay increased. Finally, rats with mamillary lesions were not impaired in learning a visual discrimination task or its reversal. The results show that extensive damage in the mamillary region can lead to significant and long lasting spatial memory impairments.
Stimulus‐Dependent Neuronal Oscillations in Cat Visual Cortex: Inter‐Columnar Interaction as Determined by Cross‐Correlation Analysis
Authors: Engel Andreas K. , König Peter , Gray Charles M. , Singer Wolf 
Published: April 2006

AbstractWe have demonstrated previously that neurons in cat striate cortex, in response to their preferred stimuli, exhibit oscillatory responses in a frequency range of 40–60 Hz. Recently, we obtained evidence that such oscillatory responses can synchronize across columns. We have now performed an extensive analysis of this phenomenon for both unit and field potential responses. In addition, we studied the stimulus conditions leading to intercolumnar synchronization. We recorded both multi‐unit activity and local field potentials from area 17 of adult cats with arrays of several electrodes. Interelectrode distances ranged from 0.4 to 12 mm. For all pairs of unit (n = 200) and field potential (n = 174) recordings, we computed auto‐ and cross‐correlation functions. The modulation of the correlograms was quantified by fitting a damped sine wave (Gabor) function to the data. Cross‐correlation analysis of the unit data revealed that in 90 out of 200 cases the recorded cells established a constant phase‐relationship of their oscillatory responses. This occurred, on average, with no phase difference. If the receptive fields were nonoverlapping, we observed a synchronization primarily between cells with similar orientation preferences. Cells with overlapping receptive fields also showed a high incidence of synchronization if their orientation preferences were different. In this latter group, synchronization occurred even in cases where the stimulus was optimal for only one of the recording sites. Under conditions of monocular instead of binocular stimulation the oscillatory modulation of the responses was attenuated, but the cross‐correlogram still indicated a significant interaction. Similar effects were seen with the application of stationary instead of moving stimuli. A synchronization of oscillatory field potential responses was observed in 136 out of 174 paired recordings. At all distances investigated, the probability of synchronization of field potential responses was independent of the orientation preferences of the cells. However, the strength of interaction decreased with increasing spatial separation. Control experiments showed that the synchronization of field potential responses was not due to volume conduction. The results demonstrate that oscillatory responses at separate cortical sites can transiently synchronize. The probability and strength of synchronization are dependent on the spatial separation of the recorded cells and their orientation preferences. In addition, the cross‐columnar synchronization is influenced by features of the visual stimulus. It is suggested that this synchronization provides a mechanism for the formation of neuronal assemblies in the visual cortex.
Stimulus‐Dependent Neuronal Oscillations in Cat Visual Cortex: Receptive Field Properties and Feature Dependence
Authors: Gray Charles M. , Engel Andreas K. , König Peter , Singer Wolf 
Published: April 2006

AbstractPreviously we have demonstrated that neurons in the striate cortex of lightly anaesthetized cats exhibit oscillatory responses at a frequency near 50 Hz in response to their preferred stimuli. Here we have used both single and multiple unit recording techniques to determine: (i) the receptive field properties and laminar distribution of cells exhibiting oscillatory responses; and (ii) the influence of changing stimulus properties on the temporal behaviour of the oscillatory responses. Oscillatory responses were detected and evaluated by computation of the autocorrelation function of the neuronal spike trains. We recorded oscillatory responses in 56% of the standard complex cells and in 12% and 11% of the simple and special complex cells. Cells exhibiting oscillatory responses were located primarily in supra‐ and infragranular layers. The oscillatory modulation amplitude of the autocorrelation function was enhanced by binocular stimulation (9 out of 16 cells) and reduced by combined stimulation with optimal and orthogonally orientated light bars (16 out of 21 cells). Changing stimulus orientation caused no change in the oscillation frequency of the sampled population of cells, while oscillation frequency increased monotonically with respect to stimulus velocity within the range of 1–12 degrees per second (10 out of 11 cells). The oscillatory modulation of the autocorrelation function increased as a function of stimulus length within the boundary of the cell's receptive field (11 out of 11 cells). In 6 out of these 11 cells, the responses did not show an oscillatory modulation if elicited by small moving spots of light. Moving stimuli were much more effective in evoking oscillatory responses than were stationary stimuli (19 out of 20 cells). In no instance, using either stationary or moving stimuli, was the phase of the oscillatory response synchronized with the stimulus. These results demonstrate functional heterogeneity among cells within striate cortex based on their temporal firing patterns and provide evidence that the temporal pattern of oscillatory cellular activity is influenced by changes in stimulus properties.