bluuebunny/crossref_metadata_2025_split huggingface dataset:
Overexpression of neuropeptide Y induced by brain‐derived neurotrophic factor in the rat hippocampus is long lasting
Authors: Reibel Sophie , Vivien‐Roels Berthe , Lê Bich‐Thuy , Larmet Yves , Carnahan Josette , Marescaux Christian , Depaulis Antoine 
Published: March 2003

AbstractBrain‐derived neurotrophic factor (BDNF) plays an important role in hippocampal neuroplasticity. In particular, BDNF upregulation in the hippocampus by epileptic seizures suggests its involvement in the neuronal rearrangements accompanying epileptogenesis. We have shown previously that chronic infusion of BDNF in the hippocampus induces a long‐term delay in hippocampal kindling progression. Although BDNF has been shown to enhance the excitability of this structure upon acute application, long‐term transcriptional regulations leading to increased inhibition within the hippocampus may account for its suppressive effects on epileptogenesis. Therefore, the long‐term consequences of a 7‐day chronic intrahippocampal infusion of BDNF (12 μg/day) were investigated up to 2 weeks after the end of the infusion, on the expression of neurotransmitters contained in inhibitory hippocampal interneurons and which display anti‐epileptic properties. Our results show that BDNF does not modify levels of immunostaining for glutamic acid decarboxylase, the rate‐limiting enzyme for γ‐aminobutyric acid (GABA) synthesis, and somatostatin. Conversely, BDNF induces a long‐lasting increase of neuropeptide Y (NPY) in the hippocampus, measured by immunohistochemistry and radioimmunoassay, outlasting the end of the infusion by at least 7 days. The distribution of BDNF‐induced neuropeptide Y immunoreactivity is similar to the pattern observed in animals submitted to hippocampal kindling, with the exception of mossy fibres which only become immunoreactive following seizure activity. The enduring increase of neuropeptide Y expression induced by BDNF in the hippocampus suggests that this neurotrophin can trigger long‐term genomic effects, which may contribute to the neuroplasticity of this structure, in particular during epileptogenesis.
Facilitation of cholinergic transmission by substance P methyl ester in the mouse hippocampal slice preparation
Authors: Kouznetsova Maria , Nistri Andrea 
Published: March 2003

AbstractUsing sharp microelectrode recording from CA1 pyramidal neurons of the adult mouse hippocampal slice preparation, we studied the modulatory action of the selective neurokinin 1 (NK1) receptor agonist substance P methyl ester (SPME), a peptidase‐resistant analogue of the peptide substance P (SP), on cholinergic responses. While SPME (0.1–1 μm) had only slight effects on membrane potential and input resistance of CA1 neurons, it largely and reversibly enhanced the membrane depolarization and oscillatory activity induced by the cholinergic agonist carbachol (CCh; 0.1–100 μm). This effect of SPME was prevented by the selective NK1 receptor antagonist SR 140333 (4 μm). In about half of the tested neurons the action of SPME was preserved in tetrodotoxin (TTX) solution, suggesting that it partly occurred at the level of pyramidal cells. Cholinergic slow excitatory postsynaptic potentials (sEPSPs) were reversibly enhanced by SPME which increased their amplitude and prolonged any associated bursting activity. This action was also blocked by SR 140333. The present results suggest that SPME largely enhances cholinergic activity in the mouse hippocampus, an effect which can help to explain, in this brain area, the recently reported facilitation of seizures by SP.
Eye position‐sensitive units in hippocampal formation and in inferotemporal cortex of the Macaque monkey
Authors: Nowicka Anna , Ringo James L. 
Published: March 2003

AbstractThe activity of 330 hippocampal and inferotemporal cells was recorded while seated monkeys with fixed heads worked in a visual discrimination task. Monkeys had to move their eyes to one of five different positions to maintain gaze on an image. The image was then extinguished and the monkeys maintained a fixed gaze on the target position in darkness to obtain a reward. The five positions of image presentation were on a horizontal line, consisting of a centre position and lateral positions which were 10 and 20 degrees right and left of it.Twenty‐two per cent of single units recorded from the hippocampus showed statistically significant sensitivity to target position in complete darkness. A similar fraction (23%) was significantly affected by target position in the light. Position sensitivity was also found among cells recorded from the inferotemporal cortex. Eye position significantly influenced the activity of 19% of inferotemporal units in darkness and 28% of inferotemporal units in the light. Interestingly, the populations of cells showing position effect in the light and in darkness were independent.
Retinal ganglion cells with NADPH‐diaphorase activity in the chick form a regular mosaic with a strong dorsoventral asymmetry that can be modelled by a minimal spacing rule
Authors: Cellerino Alessandro , Novelli Elena , Galli‐Resta Lucia 
Published: March 2003

AbstractWe have identified a class of retinal ganglion cells in the chick retina that can be labelled by NADPH‐diaphorase histochemistry. These cells have a remarkable topographic distribution, being restricted to the dorsal hemiretina, and form a highly regular mosaic, as revealed by the analysis of nearest neighbour distribution and Delaunay triangulation. Autocorrelation analysis of the mosaic of NADPH‐diaphorase‐positive retinal ganglion cells shows that the mosaic spatial organization could be generated with the single constraint that two elements cannot be closer than a given minimal distance (dmin), which we confirmed by computer simulations. In contrast with what has been observed in other mosaics, here dmin varies with cell density. However, the observed variation of the exclusion area is consistent with an original assembly of the mosaic with a constant dmin (as is the case in other mosaics), followed by differential expansion of the retina during development.
Spatial, temporal and subcellular localization of islet‐brain 1 (IB1), a homologue of JIP‐1, in mouse brain
Authors: Pellet Jean‐Baptiste , Haefliger Jaques‐Antoine , Staple Julia K. , Widmann Christian , Welker Egbert , Hirling Harald , Bonny Christophe , Nicod Pascal , Catsicas Stefan , Waeber Gérard , Riederer Beat M. 
Published: March 2003

AbstractIslet‐brain 1 (IB1) was recently identified as a DNA‐binding protein of the GLUT2 gene promoter. The mouse IB1 is the rat and human homologue of the Jun‐interacting protein 1 (JIP‐1) which has been recognized as a key player in the regulation of c‐Jun amino‐terminal kinase (JNK) mitogen‐activated protein kinase (MAPK) pathways. JIP‐1 is involved in the control of apoptosis and may play a role in brain development and aging. Here, IB1 was studied in adult and developing mouse brain tissue by in situ hybridization, Northern and Western blot analysis at cellular and subcellular levels, as well as by immunocytochemistry in brain sections and cell cultures. IB1 expression was localized in the synaptic regions of the olfactory bulb, retina, cerebral and cerebellar cortex and hippocampus in the adult mouse brain. IB1 was also detected in a restricted number of axons, as in the mossy fibres from dentate gyrus in the hippocampus, and was found in soma, dendrites and axons of cerebellar Purkinje cells. After birth, IB1 expression peaks at postnatal day 15. IB1 was located in axonal and dendritic growth cones in primary telencephalon cells. By biochemical and subcellular fractionation of neuronal cells, IB1 was detected both in the cytosolic and membrane fractions. Taken together with previous data, the restricted neuronal expression of IB1 in developing and adult brain and its prominent localization in synapses suggest that the protein may be critical for cell signalling in developing and mature nerve terminals.
Abnormal substance P release from the spinal cord following injury to primary sensory neurons
Authors: Malcangio Marzia , Ramer Matt S. , Jones Martyn G. , McMahon Stephen B. 
Published: March 2003

AbstractThe neuropeptide substance P (SP) modulates nociceptive transmission within the spinal cord. Normally, SP is uniquely contained in a subpopulation of small‐calibre axons (Aδ‐ and C‐fibres) within primary afferent nerve. However, it has been shown that after nerve transection, besides being downregulated in small axons, SP is expressed de novo in large myelinated Aβ‐fibres. In this study we investigated whether, following peripheral nerve injury, SP was released de novo from the spinal cord after selective activation of Aβ‐fibres. Spinal cords with dorsal roots attached were isolated in vitro from rats 2 weeks following distal sciatic axotomy or proximal spinal nerve lesion (SNL). The ipsilateral dorsal roots were electrically stimulated for two consecutive periods at low‐ or high‐threshold fibre strength, spinal cord superfusates were collected and SP content was determined by radioimmunoassay. SNL, but not axotomized or control rat cords, released significant amounts of SP after selective activation of Aβ‐fibres. Not only do these data support the idea that Aβ myelinated fibres contribute to neuropathic pain by releasing SP, they also illustrate the importance of the proximity of the lesion to the cell body.
Dual effect of ecdysone on adult cricket mushroom bodies
Authors: Cayre Myriam , Strambi Colette , Strambi Alain , Charpin Pierre , Ternaux Jean‐Pierre 
Published: March 2003

AbstractMushroom bodies, which are the main integrative centre for insect sensorial information, play a critical role in associative olfactory learning and memory. This paired brain structure contains interneurons grouped in a cortex, sending their axons into organized neuropiles. In the house cricket (Acheta domesticus) brain, persistent neuroblasts proliferate throughout adult life. Juvenile hormone (JH) has been shown to stimulate this proliferation [Cayre, M., Strambi, C. & Strambi, A. (1994) Nature, 368, 57–59]. In the present study, the effect of morphogenetic hormones on mushroom body cells maintained in primary culture was examined. Whereas JH did not significantly affect neurite growth, ecdysone significantly stimulated neurite elongation. Moreover, ecdysone also acted on neuroblast proliferation, as demonstrated by the reduced number of cells labelled with 5‐bromodeoxyuridine following ecdysone application. Heterospecific antibodies raised against ecdysone receptor protein and ultraspiracle protein, the two heterodimers of ecdysteroid receptors, showed positive immunoreactivity in nervous tissue extracts and in nuclei of mushroom body cells, indicating the occurrence of putative ecdysteroid receptors in cricket mushroom body cells. These data indicate a dual role for ecdysone in adult cricket mushroom bodies: this hormone inhibits neuroblast proliferation and stimulates interneuron differentiation. These results suggest that a constant remodelling of mushroom body structure could result from physiological changes in hormone titres during adult life.
Inositol 1,4,5‐trisphosphate and adenophostin analogues induce responses in turtle olfactory sensory neurons
Authors: Kashiwayanagi Makoto , Tatani Kazuya , Shuto Satoshi , Matsuda Akira 
Published: March 2003

AbstractUsing the whole‐cell mode of the patch‐clamp technique, we recorded inward currents in response to inositol‐1,4,5‐trisphosphate (IP3) and adenophostin analogues in turtle olfactory sensory neurons. Dialysis of IP3 into the neurons induced inward currents with an increase in membrane conductance in a dose‐dependent manner under the voltage‐clamp conditions (holding potential −70 mV). The application of Ca2+‐free Ringer solution to neurons previously dialysed with IP3 induced inward currents that were reversibly inhibited by application of Na+, Ca2+‐free Ringer solution, normal Ringer solution or 10 μm ruthenium red. Dialysis of the adenophostin analogues, novel IP3 receptor ligands, also induced inward currents with an increase in membrane conductance. The magnitude of the responses to the adenophostin analogues varied among these derivatives. The application of Ca2+‐free Ringer solution to neurons previously dialysed with the adenophostin analogues induced inward currents that were inhibited by the application of normal Ringer solution. The reversal potential of inward currents induced by an adenophostin analogue was similar to that induced by IP3, suggesting that inward currents induced by the adenophostin analogue were generated by a similar ionic mechanism to that induced by IP3. The present study demonstrated that IP3‐mediated transduction pathways exist in turtle olfactory receptor neurons and that adenophostin analogues act as agonists of IP3.
The seasonal pattern of cell proliferation and neuron number in the dentate gyrus of wild adult eastern grey squirrels
Authors: Lavenex Pierre , Steele Michael A. , Jacobs Lucia F. 
Published: March 2003

AbstractThe dentate gyrus is one of two areas in the mammalian brain that produces neurons in adulthood. Neurogenesis (proliferation, survival, and differentiation of new neurons) is regulated by experience, and increased neurogenesis appears to be correlated with improved spatial learning in mammals and birds. We tested the hypothesis that in long‐lived mammals that scatter‐hoard food, seasonal variations in spatial memory processing (i.e. increased processing during caching season in the autumn) might correlate with changes in neurogenesis and neuron number in the granule cell layer of the dentate gyrus (gcl DG). We investigated the rate of cell proliferation and the total number of neurons in the granule cell layer of wild adult eastern grey squirrels (Sciurus carolinensis) at three different times of the year (October, January and June). We found no seasonal differences in cell proliferation rate or in total neuron number in the granule cell layer. Our findings are in agreement with those of previous studies in laboratory mice and rats, and in free‐ranging, food‐caching, black‐capped chickadees, as well as with current hypotheses regarding the relationship between neurogenesis and learning. Our results, however, are also in agreement with the hypothesis that neurogenesis in the dentate gyrus represents a maintenance system that may be regulated by environmental factors, and that changes in total neuron number previously reported in rodents represent developmental changes rather than adult plasticity. The patterns observed in mature wild rodents, such as free‐ranging squirrels, may represent more accurately the extent of hippocampal plasticity in adult mammals.
Neurokinin 1 receptor expression by neurons in laminae I, III and IV of the rat spinal dorsal horn that project to the brainstem
Authors: Todd Andrew J. , McGill Margaret M. , Shehab Safa A. S. 
Published: March 2003

AbstractLarge neurons in laminae III and IV of the spinal cord which express the neurokinin 1 receptor and have dendrites that enter the superficial laminae are a major target for substance P (SP)‐containing (nociceptive) primary afferents. Although some of these neurons project to the thalamus, we know little about other possible projection targets. The main aim of this study was to determine whether all cells of this type are projection neurons and to provide information about brainstem sites to which they project. Injections of cholera toxin B subunit were made into four brainstem areas that receive input from the spinal cord, and the proportion of cells of this type in the L4 spinal segment that were retrogradely labelled was determined in each case. The results suggest that most of these cells (>90%) project to the contralateral lateral reticular nucleus (or to a nearby region), while many (>60%) send axons to the lateral parabrachial area and some to the dorsal part of the caudal medulla. However, few of these cells project to the periaqueductal grey matter. As lamina I neurons with the neurokinin 1 receptor appear to be important in the generation of hyperalgesia, we also examined projection neurons in this lamina and found that for each injection site the great majority possessed the receptor. These results demonstrate that dorsal horn neurons which express the neurokinin 1 receptor contribute to several ascending pathways that are thought to be important in pain mechanisms.
In vivo survival requirement of a subset of nodose ganglion neurons for nerve growth factor
Authors: Forgie Alison , Kuehnel Florian , Wyatt Sean , Davies Alun M. 
Published: March 2003

AbstractThe sensory neurons of the nodose ganglion are the classic example of a population of peripheral nervous system neurons that do not require nerve growth factor (NGF) for survival during development but are dependent on other neurotrophins. We have re‐examined this assertion by studying the development of the nodose ganglion of mice that have a null mutation in the NGF gene. Compared with wild‐type embryos, the number of neurons undergoing apoptosis was elevated in NGF –/– mice, resulting in a significant reduction in the total number of neurons in the ganglion by the end of embryonic development. TrkA, the NGF receptor tyrosine kinase, was expressed in the nodose ganglion throughout development and there was a marked decrease in TrkA mRNA expression in the nodose ganglion of NGF –/– embryos. Although the in vitro survival of the majority of nodose neurons was promoted by brain‐derived neurotrophic factor (BDNF), a minor proportion was supported by NGF in cultures established over a range of embryonic stages. These results clearly demonstrate that a subset of nodose ganglion neurons depends on NGF for survival during development. The finding that the expression of tyrosine hydroxylase (TH) mRNA was unaffected in the nodose ganglia of NGF‐deficient embryos indicates that this NGF‐dependent subset is distinct from the subset of catacholaminergic neurons in the nodose ganglion.
Oxytocin induces preservation of social recognition in male rats by activating α‐adrenoceptors of the olfactory bulb
Authors: Dluzen Dean E. , Muraoka Shinichiro , Engelmann Mario , Ebner Karl , Landgraf Rainer 
Published: March 2003

AbstractIn this report, a series of four experiments was performed to evaluate the relationship between the olfactory bulb norepinephrine system and intra‐olfactory bulb infusion of oxytocin in the preservation of social memory responses. The present data indicate that oxytocin exerts this preservation of social recognition through a specific, receptor‐mediated mechanism within the olfactory bulb (experiment 1). The involvement of the olfactory bulb norepinephrine system is revealed by the demonstration that retrodialysis of oxytocin into the olfactory bulb increases norepinephrine release (experiment 4). Our data suggest that the increased output of olfactory bulb norepinephrine resulting from oxytocin appears to activate α‐adrenoceptors to produce this preservation in recognition because infusions of clonidine into the olfactory bulb preserve recognition responses in a manner similar to that observed with oxytocin (experiment 2). In addition, a co‐infusion of oxytocin with phentolamine abolishes recognition responses (experiment 3). Accordingly, this model affords the opportunity to study neuropeptide–catecholamine interactions, link these interactions with a specific behavioural outcome and identify a novel function/site of action for oxytocin in the male.
Hippocampal stem cells differentiate into excitatory and inhibitory neurons
Authors: Vicario‐Abejón Carlos , Collin Carlos , Tsoulfas Pantelis , McKay Ronald D. G. 
Published: March 2003

AbstractStem cell technology promises new and rapid advances in cell therapy and drug discovery. Clearly, the value of this approach will be limited by the differentiated functions displayed by the progeny of stem cells. The foetal and adult central nervous system (CNS) harbour stem cells that can be expanded in vitro and differentiate into immature neurons and glia. Surprisingly, we do not know if neurons derived from stem cells form synapses, a definitive feature of neuronal function. Neuronal differentiation is a complex process and in this paper we establish conditions that permit extensive maturation of neurons in the presence of neurotrophins. These conditions permit the differentiation of rat hippocampal stem cells into both excitatory (glutamatergic) and inhibitory (GABAergic) neurons. The proportion of excitatory and inhibitory synapses was strongly influenced by specific neurotrophins, and these responses reflect the region of origin of the stem cells in the brain. These data show that stem cells can be used to study mechanisms of excitation and inhibition in the nervous system.
Effects of monoamines on interneurons in four spinal reflex pathways from group I and/or group II muscle afferents
Authors: Jankowska E. , Hammar I. , Chojnicka B. , Hedén C. H. 
Published: March 2003

AbstractEffects of locally applied serotonin (5‐HT) and noradrenaline (NA) were tested on extracellularly recorded responses of single spinal interneurons in deeply anaesthetized cats. These effects were tested on: (i) interneurons mediating reciprocal inhibition from group Ia afferents; (ii) interneurons mediating non‐reciprocal inhibition from group Ia and Ib afferents; (iii) intermediate zone interneurons co‐excited by group I and II afferents; and (iv) dorsal horn interneurons excited by group II afferents. Effects of monoamines were tested on responses evoked at latencies compatible with monosynaptic coupling. Responses evoked by group Ia and/or Ib muscle afferents were facilitated in all of the tested interneurons both by NA and 5‐HT. Responses evoked by group II muscle afferents were depressed in the majority of the interneurons but were facilitated in some of them. 5‐HT depressed these responses in all dorsal horn interneurons and in one subpopulation of intermediate zone interneurons, while it facilitated them in another subpopulation of intermediate zone interneurons. NA depressed them in all intermediate zone interneurons and in one subpopulation of dorsal horn interneurons, while it facilitated them in another subpopulation of dorsal horn interneurons. The results of this study lead to the conclusions that: (i) modulation of synaptic actions of muscle spindle and tendon organ afferents on spinal interneurons by 5‐HT and NA is related to both the type of the afferent and the functional type of the interneuron; and that (ii) 5‐HT and NA counteract each others' actions on some interneuronal types but mutually enhance them on the others.
Afferent‐specific modulation of short‐term synaptic plasticity by neurotrophins in dentate gyrus
Authors: Asztely Fredrik , Kokaia Merab , Olofsdotter Klara , Örtegren Unn , Lindvall Olle 
Published: March 2003

AbstractNeurotrophins modulate synaptic transmission and plasticity in the adult brain. We here show a novel feature of this synaptic modulation, i.e. that two populations of excitatory synaptic connections to granule cells in the dentate gyrus, lateral perforant path (LPP) and medial perforant path (MPP), are differentially influenced by the neurotrophins BDNF and NT‐3. Using field recordings and whole‐cell patch‐clamp recordings in hippocampal slices, we found that paired‐pulse (PP) depression at MPP–granule cell synapses was impaired in BDNF knock‐out (+/–) mice, but PP facilitation at LPP synapses to the same cells was not impaired. In accordance, scavenging of endogenous BDNF with TrkB–IgG fusion protein also impaired PP depression at MPP–granule cell synapses, but not PP facilitation at LPP–granule cell synapses. Conversely, in NT‐3+/– mice, PP facilitation was impaired at LPP–granule cell synapses whilst PP depression at MPP–granule cell synapses was unaffected. These deficits could be reversed by application of exogenous neurotrophins in an afferent‐specific manner. Our data suggest that BDNF and NT‐3 differentially regulate the synaptic impact of different afferent inputs onto single target neurons in the CNS.