bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spatiotemporal distribution of dying neurons during early mouse development
Authors: Van Den Eijnde S. M. , Lips J. , Boshart L. , Vermeij‐Keers C. , Marani E. , Reutelingsperger C. P. M. , De Zeeuw C. I. 
Published: March 2003

AbstractApoptosis is a critical cellular event during several stages of neuronal development. Recently, we have shown that biotinylated annexin V detects apoptosis in vivo in various cell lineages of a wide range of species by binding to phosphatidylserines that are exposed at the outer leaflet of the plasma membrane. In the present study, we tested the specificity by which annexin V binds apoptotic neurons, and subsequently investigated developmental cell death in the central and peripheral nervous system of early mouse embryos at both the cellular and histological level, and compared the phagocytic clearance of apoptotic neurons with that of apoptotic mesodermal cells. Our data indicate: (i) that biotinylated annexin V can be used as a sensitive marker that detects apoptotic neurons, including their extensions at an early stage during development; (ii) that apoptosis plays an important part during early morphogenesis of the central nervous system, and during early quantitative matching of brain‐derived neurotrophic factor and neurotrophic factor 3 responsive postmitotic large clear neurons in the peripheral ganglia with their projection areas; and (iii) that apoptotic neurons are removed by a process that differs from classical phagocytosis of non‐neuronal tissues.
Ca2+ regulation of a large conductance K+ channel in cultured rat cerebellar Purkinje neurons
Authors: Jacquin T. D. , Gruol D. L. 
Published: March 2003

AbstractThe calcium sensitivity of a large conductance voltage‐sensitive potassium channel found in cultured rat cerebellar Purkinje neurons was studied in membrane patches from the somatic region of the cultured Purkinje neurons using single‐channel recording techniques. The potassium channel had a conductance of ≈ 94 picosiemens (pS) under physiologic ionic conditions and was active at depolarized membrane potentials. Activity due to this channel type was not observed when the saline at the internal surface of the membrane was calcium free. Low intracellular calcium concentration (10 nm) triggered channel activity at depolarized membrane potentials. Channel activity increased further with increasing intracellular calcium concentrations and was evident at more negative membrane potentials. The high sensitivity of this potassium channel type to intracellular calcium and its abundance in the Purkinje neuron membrane may reflect a prominent role in the control of action potential duration and interspike interval when the neurons are firing in a rapid, repetitive mode.
Q/R editing of the rat GluR5 and GluR6 kainate receptors in vivo and in vitro: evidence for independent developmental, pathological and cellular regulation
Authors: Bernard Anne , Ferhat Lotfi , Dessi Frédéric , Charton Gérard , Represa Alfonso , Ben‐Ari Yezekiel , Khrestchatisky Michel 
Published: March 2003

AbstractKainate (KA) is a potent neuroexcitatory agent in several areas of the adult brain, with convulsant and excitotoxic properties that increase as ontogeny proceeds. Besides its depolarizing actions, KA may enhance intracellular accumulation of Ca 2+ to promote selective neuronal damage. The effects of KA are mediated by specific receptors recently considered to be involved in fast neurotransmission and that can be activated synaptically. KA receptors, e.g. GluR5 and GluR6 have been characterized by molecular cloning. Structure–function relationships indicate that in the MII domain of these KA receptors, a glutamine (Q) or arginine (R) residue determines ion selectivity. The arginine stems from post‐transcriptional editing of the GluR5 and GluR6 pre‐RNAs, and the unedited and edited versions of GluR6 elicit distinct Ca2+ permeability. Using a PCR‐based approach, we show that in vivo, Q/R editing in the GluR5 and GluR6 mRNAs is modulated during ontogeny and differs substantially in a variety of nervous tissues. GluR5 editing is highest in peripheral nervous tissue, e.g. the dorsal root ganglia, where GluR6 expression is barely detectable. In contrast, GluR6 editing is maximal in forebrain and cerebellar structures where GluR5 editing is lower. Intra‐amygdaloid injections of KA provide a model of temporal lobe epilepsy, and we show that following seizures, the extent of GluR5 and GluR6 editing is altered in the hippocampus. However, in vitro, high levels of glutamate and potassium‐induced depolarizations have no effect on GluR5 and GluR6 Q/R editing. GluR6 editing is rapidly enhanced to maximal levels in primary cultures of cerebellar granule neurons but not in cultured hippocampal pyramidal neurons. Finally, we show that cultured glial cells express partially edited GluR6 mRNAs. Our results indicate that Q/R editing of GluR5 and GluR6 mRNAs is structure‐, cell type‐ and time‐dependent, and suggest that editing of these mRNAs is not co‐regulated.
Anandamide and WIN 55212‐2 inhibit cyclic AMP formation through G‐protein‐coupled receptors distinct from CB1 cannabinoid receptors in cultured astrocytes
Authors: Sagan Sandrine , Venance Laurent , Torrens Yvette , Cordier Jocelyne , Glowinski Jacques , Giaume Christian 
Published: March 2003

AbstractThe effects of anandamide and the cannabinoid receptor agonists WIN 55212‐2 and CP 55940 on the evoked formation of cyclic AMP were compared in cultured neurons and astrocytes from the cerebral cortex and striatum of mouse embryos. The three compounds inhibited the isoproterenol‐induced accumulation of cyclic AMP in neuronal cells, and these responses were blocked by the selective CB1 receptor antagonist SR 141716A. The three agonists were more potent in cortical than striatal neurons. Interestingly, WIN 55212‐2, CP 55940 and anandamide also inhibited the isoproterenol‐evoked accumulation of cyclic AMP in astrocytes but, in contrast to WIN 55212‐2 and CP 55940, anandamide was much more potent in striatal than cortical astrocytes. Inhibition was prevented by pertussis toxin pretreatment, but not blocked by SR 141716A. Therefore, G‐protein‐coupled receptors, distinct from CB1 receptors, are involved in these astrocytic responses. Moreover, specific binding sites for [3H]‐SR 141716A were found in neurons but not astrocytes. Furthermore, using a polyclonal CB1 receptor antibody, staining was observed in striatal and cortical neurons, but not in striatal and cortical astrocytes. Taken together, these results suggest that glial cells possess G‐protein‐coupled receptors activated by cannabinoids distinct from the neuronal CB1 receptor, and that glial cells responses must be taken into account when assessing central effects of cannabinoids.
GABAB‐receptor splice variants GB1a and GB1b in rat brain: developmental regulation, cellular distribution and extrasynaptic localization
Authors: Fritschy Jean‐Marc , Meskenaite Virginia , Weinmann Oliver , Honer Michael , Benke Dietmar , Mohler Hanns 
Published: March 2003

AbstractGABAB (γ‐aminobutyric acid)‐receptors have been implicated in central nervous system (CNS) functions, e.g. cognition and pain perception, and dysfunctions including spasticity and absence epilepsy. To permit an analysis of the two known GABAB‐receptor splice variants GABAB‐R1a (GB1a) and GABAB‐R1b (GB1b), their distribution pattern has been differentiated in the rat brain, using Western blotting and immunohistochemistry with isoform‐specific antisera. During postnatal maturation, the expression of the two splice variants was differentially regulated with GB1a being preponderant at birth. In adult brain, GB1b‐immunoreactivity (‐IR) was predominant, and the two isoforms largely accounted for the pattern of GABAB‐receptor binding sites in the brain. Receptor heterogeneity was pronounced in the hippocampus, where both isoforms occurred in CA1, but only GB1b in CA3. Similarly, in the cerebellum, GB1b was exclusively found in Purkinje cells in a zebrin‐like pattern. The staining was most pronounced in Purkinje cell dendrites and spines. Using electron microscopy, over 80% of the spine profiles in which a synaptic contact with a parallel fibre was visible contained GB1b‐IR at extrasynaptic sites. This subcellular localization is unrelated to GABAergic inputs, indicating that the role of GABAB‐receptors in vivo extends beyond synaptic GABAergic neurotransmission and may, in the cerebellum, involve taurine as a ligand.
Electrophysiological evidence for a reciprocal interaction between amphetamine and cocaine‐related drugs on rat midbrain dopaminergic neurons
Authors: Scarponi Mariangela , Bernardi Giorgio , Mercuri Nicola B. 
Published: March 2003

AbstractTo determine the functional interactions occurring between amphetamine and cocaine‐like drugs on a single neuron, we used intracellular single‐electrode voltage‐clamp recordings from dopaminergic cells of the rat midbrain maintained in vitro. In the presence of cocaine (3–30 μm), the outward current caused by amphetamine (100 μm) on cells held at about – 60 mV was attenuated. The degree of attenuation of the amphetamine‐induced response was almost the same for 3 and 30 μm cocaine (44 and 51% of control, respectively). This effect of cocaine was reversible. We also tested other DA‐uptake inhibitors (nomifensine and 4‐phenyltetrahydroisoquinoline) against the amphetamine‐induced outward current. Both drugs enhanced the effects of dopamine (DA) while reducing the outward response caused by amphetamine. Pretreatment of the animals with reserpine (12 mg/kg/i.p.), which irreversibly depletes the vesicular DA stores, neither affected the amplitude of the current caused by amphetamine nor changed the cocaine‐induced attenuation of the membrane responses to amphetamine. Interestingly, when amphetamine (3 μm) was superfused on the dopaminergic neurons prior and during the application of cocaine, the DA‐uptake blocker was no longer able to potentiate the outward response caused by the superfusion of DA. Taken together, these data suggest that: (i) amphetamine and cocaine interact with the DA transporter to produce distinct actions which under certain circumstances can compete with each other; (ii) the amphetamine‐induced release of DA from the somata and dendrites of the dopaminergic cells is, at least in part, related to the reverse operation of the DA transporter and is not dependent on the integrity of the vesicular content of the catecholamine.
Neuregulin is a mitogen and survival factor for olfactory bulb ensheathing cells and an isoform is produced by astrocytes
Authors: Pollock Graeme S. , Franceschini Isabelle A. , Graham Gerry , Marchionni Mark A. , Barnett Susan C. 
Published: March 2003

AbstractThe rat olfactory bulb is an exceptional CNS tissue. Unlike other areas of the brain, growing axons are able to enter the olfactory bulb and extend within this CNS environment throughout adult life. It appears that the glial cells of the olfactory system, known as olfactory bulb ensheathing cells (OBECs), may have an important role in this remarkable process of CNS neural regeneration. OBECs are unusual glial cells, possessing properties of both astrocytes and Schwann cells. In this study we show that astrocytes (in the form of astrocyte‐conditioned medium; ACM) produce two critical regulatory functions for OBECs: mitogenic activity and a survival factor. Interestingly, the ACM‐derived activity for OBECs appears to reside in a signalling protein(s) belonging to the neuregulin (NRG) family of growth factors, and specifically appears to coincide with one or more products of the nrg‐1 gene. Our observations provide evidence for the following: recombinant human neu differentiation factors (NDFβ1, ‐2 and ‐3) are mitogenic to OBECs; the activity in ACM can be neutralized by NDF antibodies; these same antibodies detect a 50‐kDa, non‐heparin binding protein in concentrated ACM; astrocytes express detectable nrg‐1 transcripts; and OBECs express functional NRG receptors erbB2 and erbB4.
ZFM1/SF1 mRNA in rat and gerbil brain after global ischaemia
Authors: Covini N. , Tamburin M. , Consalez G. , Salvati P. , Benatti L. 
Published: March 2003

AbstractCerebral ischaemia results in significant brain damage, but the molecular mechanisms associated with ischaemia‐induced brain injury are not well defined. We have adopted an improved differential‐display method to search for new ischaemia‐related genes. Among the different cDNAs isolated following transient forebrain ischaemia in rat, PH3.3 was selected for further studies. The search for homologies revealed that it is the rat homologue to human zinc finger motif 1 (ZFM1), also called mammalian splicing factor 1 (SF1). With Northern blot, PH3.3 hybridized with three mRNA species of 2.3, 2.9 and 3.6 kb, significantly increased at 6 h and 5 days after the ischaemic insult. These findings were extended also to another animal model. In situ hybridization in ischaemic gerbils showed that PH3.3 mRNA was induced in the dentate gyrus as early as 4 h post‐ischaemia. Expression peaked at 2 days in the whole hippocampus and cortex, and then progressively decreased towards sham levels. By day 4, expression had disappeared almost entirely from the cells in the CA1 region of the hippocampus, concomitant with the degeneration of pyramidal neurons. Interestingly, ZFM1/SF1 has been recently identified as activated following p53‐induced apoptosis. Several lines of evidence suggest that p53 may play two roles in the post‐ischaemic brain. The primary role of p53 is to activate DNA repair processes, but if repair fails, apoptosis will be initiated. Thus, ZFM1/SF1 may represent a relevant link between p53 and the neuroprotective/neurodegenerative processes which follow cerebral ischaemia.
Activity‐dependent regulation of alternative splicing patterns in the rat brain
Authors: Daoud Rosette , Da Penha Berzaghi Maria , Siedler Frank , Hübener Mark , Stamm Stefan 
Published: March 2003

AbstractAlternative splicing plays an important role in the expression of genetic information. Among the best understood alternative splicing factors are transformer and transformer‐2, which regulate sexual differentiation in Drosophila. Like the Drosophila genes, the recently identified mammalian homologues are subject to alternative splicing. Using an antibody directed against the major human transformer‐2 beta isoform, we show that it has a widespread expression in the rat brain. Pilocarpine‐induced neuronal activity changes the alternative splicing pattern of the human transformer‐2‐beta gene in the brain. After neuronal stimulation, a variant bearing high similarity to a male‐specific Drosophila tra‐2179 isoform is switched off in the hippocampus and is detectable in the cortex. In addition, the ratio of another short RNA isoform (htra2‐beta2) to htra2‐beta1 is changed. Htra2‐beta2 is not translated into protein, and probably helps to regulate the relative amounts of htra2‐beta1 to beta3. We also observe activity‐dependent changes in alternative splicing of the clathrin light chain B, c‐src and NMDAR1 genes, indicating that the coordinated change of alternative splicing patterns might contribute to molecular plasticity in the brain.
SNARE complex at the ribbon synapses of cochlear hair cells: analysis of synaptic vesicle‐ and synaptic membrane‐associated proteins
Authors: Safieddine Saaid , Wenthold Robert J. 
Published: March 2003

AbstractNeurotransmitters are released via exocytosis of synaptic vesicles involving a fusion complex consisting of a set of highly conserved proteins, which form a multiprotein complex resulting in the docking of synaptic vesicles at the site of release. There are three major differences between cochlear hair cell synapses and CNS synapses: (i) hair cells have a specialized structure, the synaptic ribbon, to which synaptic vesicles are attached; (ii) hair cells can maintain high and sustained release of neurotransmitter; and (iii) hair cells lack synaptophysin and synapsin. These differences suggest that an unconventional mechanism of neurotransmitter release may be involved at ribbon synapses. In this study we used different and complementary approaches to determine whether or not ribbon‐containing hair cells of the cochlea express any component of the core fusion complex found in conventional synapses. Syntaxin 1, the synaptic membrane synaptosome‐associated protein (SNAP)‐25 and vesicle‐associated membrane protein (VAMP or synaptobrevin) were found to be present in the organ of Corti of both rat and guinea‐pig, as shown by reverse transcription polymerase chain reaction and Western blotting. In situ hybridization and immunocytochemistry showed mRNA and protein expression, respectively, in both inner and outer hair cells. Synaptotagmins I and II, generally considered to play major roles in neurotransmitter release at central synapses, were not detected in the organ of Corti.
Lasting reduction in mesolimbic dopamine neuronal activity after morphine withdrawal
Authors: Diana Marco , Muntoni Anna Lisa , Pistis Marco , Melis Miriam , Gessa Gian Luigi 
Published: March 2003

AbstractThe activity of mesolimbic dopaminergic neurons was investigated in rats at various times after a chronic regimen of morphine, which produced, upon suspension, a marked somatic withdrawal syndrome. Single‐cell extracellular recording techniques, coupled with antidromic identification from the nucleus accumbens, were used to monitor neuronal activity while behavioural observations allowed quantification of the somatic signs of morphine withdrawal. Temporal correlation of electrophysiological indices, such as firing rate and burst firing, with scores obtained through behavioural assessments proved negative, in that somatic signs were pronounced at 24 h after suspension of treatment and then subsided to control values at 72 h after the last morphine injection. In contrast, the firing rate and burst firing of mesolimbic dopaminergic neurons were found to be reduced at 1, 3 and 7 days after morphine withdrawal. After 14 drug‐free days, electrophysiological analysis revealed an apparent normalization of various parameters. However, at this time, intravenous administration of morphine produced an increment of electrical activity which was significantly higher than that obtained in control (saline treated) rats. Further, administration of the opiate antagonist naltrexone, administered without prior morphine, at 3, 7 and 14 days after the last morphine administration, failed to alter dopaminergic neuronal activity. The results indicate: (i) that the activity of mesolimbic dopaminergic neurons remains reduced well after somatic signs of withdrawal have disappeared; (ii) after 14 days of withdrawal, the augmented magnitude of the electrophysiological response to exogenous morphine suggests an increased sensitivity of opiate receptors; and (iii) the lack of relationship between dopaminergic activity and somatic signs of withdrawal corroborates the notion that dopaminergic activity in the mesolimbic system does not participate in the neurobiological mechanisms responsible for somatic withdrawal. The present results may be relevant to the phenomenon of drug addiction in humans and consequent relapse after drug‐free periods.
Properties of NMDA receptors in rat spinal cord motoneurons
Authors: Paleček Jir í , Abdrachmanova Galya , Vlachová Viktorie , Vyklický Ladislav 
Published: March 2003

AbstractPostnatal development and properties of N‐methyl‐d‐aspartate (NMDA) receptors were studied with whole‐cell and outside‐out patch‐clamp techniques in interneurons and fluorescence‐labelled motoneurons in rat spinal cord slices. Both the absolute amplitude of NMDA‐induced currents and currents normalized with respect to the motoneuron capacitance increased significantly at postnatal days 10–13 when compared to the responses evoked at postnatal days 2–3. The mean amplitude of the responses to kainate also increased in motoneurons of postnatal days 10–13. Single‐channel currents induced by low concentrations of glutamate, exhibited four distinct amplitude levels corresponding to 19.2 ± 2.4 pS, 38.4 ± 3.5 pS, 56.3 ± 2.4 pS and 69.6 ± 3.7 pS. In contrast, the conductance of single channels, recorded under identical conditions, in rat spinal cord interneurons was less, 15.3 ± 3.2 pS, 29.9 ± 5.4 pS, 46.7 ± 4.8 pS and 62.4 ± 3.9 pS. The high (56/70 pS) conductance single‐channel openings in motoneuron patches were sensitive to NMDA receptor inhibitors d‐2‐amino‐5‐phosphonovalerate, 7‐chlorokynurenic acid and ifenprodil. Whole‐cell NMDA‐evoked currents were blocked in a voltage‐dependent manner by extracellular Mg2+ with an apparent dissociation constant for Mg2+ binding at 0 mV of 1.8 ± 0.5 mm. The conductance and relative distribution of NMDA receptor channel openings induced by 1 μm glutamate in patches isolated from the motoneurons were independent of age from postnatal day 4 to 14. The results suggest that the properties of NMDA receptor channels in motoneurons differ from those in spinal cord interneurons and cells transfected with NR1/NR2 subunits.
Myelin‐associated oligodendrocytic basic protein is essential for normal arrangement of the radial component in central nervous system myelin
Authors: Yamamoto Yoichi , Yoshikawa Hiroo , Nagano Seiichi , Kondoh Gen , Sadahiro Shigeki , Gotow Takahiro , Yanagihara Takehiko , Sakoda Saburo 
Published: March 2003

AbstractWe previously reported that myelin‐associated oligodendrocytic basic protein (MOBP) was abundantly expressed in the central nervous system (CNS) myelin, and shared several characteristics with myelin basic protein (MBP). In particular, a cluster of positively charged amino acids was considered to facilitate compaction of the cytoplasmic face of the myelin sheath, as in the case of MBP. However, the contribution of MOBP in forming and maintaining the myelin sheath still remains unclear. Recent investigations showed that one isoform of MOBP was expressed in the embryo prior to myelination, and MOBP isoforms were colocalized with the microtubular network and nucleus in vitro. To explore the role of MOBP in vivo, we generated MOBP‐deficient mice and analysed the CNS myelin. Surprisingly, the compact myelin was formed, however, the myelin from MOBP‐deficient mice exposed to hexachlorophene, a known dysmyelinating agent, showed widening of the major dense lines. These results suggest that MOBP is not essential for myelin formation, but reinforces the apposition of the cytoplasmic faces of the myelin sheath. A striking phenotype of MOBP‐deficient mice was the presence of the straight ‘condensed’ radial component. This component has been described as a tight junction‐like complex running radially and zig‐zag through the CNS myelin sheath between inner and outer mesaxons. These results suggest that MOBP is essential for normal arrangement of the radial component.