bluuebunny/crossref_metadata_2025_split huggingface dataset:
The NO‐cGMP pathway in the rat locus coeruleus: electrophysiological, immunohistochemical and in situ hybridization studies
Authors: Xu Zhi‐Qing David , De Vente Jan , Steinbusch Harry , Grillner Sten , Hökfelt Tomas 
Published: March 2003

AbstractThe effect of two nitric oxide (NO) donors, SIN‐1 and DEA/NO, as well as of the inactive SIN‐1 derivative molsidomin, was studied on locus coeruleus (LC) neurons in a slice preparation using intracellular recordings. In addition, the effect of the guanylate cyclase inhibitor ODQ was analysed. Furthermore, the effect of NO donors on cyclic guanosine monophosphate (GMP) levels in the LC was studied using the indirect immunofluorescence technique, and the expression of soluble guanylyl cyclase with in situ hybridization. In 36 of 66 LC neurons extracellular application of SIN‐1 and DEA/NO caused a hyperpolarization and a decrease in apparent input resistance. In almost 20% of neurons SIN‐1 increased the firing rate. No effect could be recorded with the brain‐inactive SIN‐1 derivative molsidomin. The membrane permeable cGMP analogue 8‐bromo‐cGMP imitated the action of SIN‐1. The hyperpolarizing effect of SIN‐1 and DEA/NO was attenuated by preincubation with the guanylyl cyclase inhibitor ODQ. The immunohistochemical analysis revealed lack of cGMP immunostaining in non‐stimulated slices, whereas SIN‐1 dramatically increased this staining in about 40% of the LC neurons, and these neurons were all tyrosine hydroxylase positive, that is noradrenergic. A large proportion of the LC neurons expressed soluble guanylyl cyclase mRNA. The present and previous results suggest that NO, released from a small number of non‐noradrenergic neurons in the LC, mainly has an inhibitory influence on many noradrenergic neurons, by upregulating cGMP levels via stimulation of soluble guanylyl cyclase. As nitric oxide synthase is present only in a small number of non‐noradrenergic neurons (Xu et al. 1994), a few neurons may influence a large population of noradrenergic LC neurons, which in turn may control activity in many regions of the central nervous system.
Select types of supporting cell in the inner ear express aquaporin‐4 water channel protein
Authors: Takumi Yutaka , Nagelhus Erlend Arnulf , Eidet Jo , Matsubara Atsushi , Usami Shin‐ichi , Shinkawa Hideichi , Nielsen Søren , Ottersen Ole Petter 
Published: March 2003

AbstractAquaporins (AQPs) confer a high water permeability on cell membranes and play important parts in secretory and absorptive epithelia in kidney and other organs. Here we investigate whether AQPs are expressed in the sensory epithelia of the inner ear, where a precise volume regulation is crucial. By use of specific antibodies it was found that the inner ear contains AQP1 and 4 while being devoid of detectable levels of AQP2, 3 or 5. Immunofluorescence and postembedding immunogold labelling revealed a strictly non‐epithelial distribution of AQP1, confirming previous data. In contrast, AQP4 protein and mRNA (visualized by in situ hybridization) were concentrated in select types of supporting cell, including Hensen's cells and inner sulcus cells. Immunogold particles signalling AQP4 were confined to the basolateral plasma membrane of Hensen's cells and to the basal plasma membrane of Claudius cells and inner sulcus cells. AQP4 was also found in supporting cells of the vestibular end organs, but was absent from transitional epithelial cells and dark cells. Strong labelling for AQP4 and AQP4‐mRNA was associated with the central part of the cochlear and vestibular nerves. Hair cells were consistently unlabelled. Our findings indicate that AQP4 may facilitate osmotically driven water fluxes in the sensory epithelia of the inner ear and thus contribute to the volume and ion homeostasis at these sites.
Matrix‐assisted laser desorption/ionization time of flight mass spectrometric analysis of the pattern of peptide expression in single neurons resulting from alternative mRNA splicing of the FMRFamide gene
Authors: Worster Belinda M. , Yeoman Mark S. , Benjamin Paul R 
Published: March 2003

AbstractMALDI‐ToF MS (matrix‐assisted laser desorption/ionization time of flight mass spectrometry) has become a fast, reliable and sensitive technique for the identification of neuropeptides in biological tissues. Here, we applied this technique to identified neurons of the cardioregulatory network in the snail Lymnaea that express the FMRFamide gene. This enabled us to study the complex processing of the FMRFamide gene at the level of single identified neurons. In the CNS of Lymnaea, FMRFamide‐like and additional peptides are encoded by a common, multiexon gene. Alternate mRNA splicing of the FMRFamide gene leads to the production of two different mRNAs. Type 1 mRNA (exon II) encodes for the tetrapeptides (FLRF/FMRFamide), whereas Type 2 (exons III–V) encodes for the heptapeptides (SDPFLRFamide/GDPFLRFamide). Previous in situ hybridization and immunocytochemical studies indicated that these two transcripts are expressed in the CNS neurons of Lymnaea in a differential and mutually exclusive manner. Two single identified neurons of the cardiorespiratory network, the Ehe neuron and the visceral white interneuron (VWI), were known to express the FMRFamide gene (Ehe, type 1 mRNA; VWI, type 2 mRNA). MALDI‐ToF MS analysis of these neurons and other neurons expressing the FMRFamide gene confirmed the mutually exclusive expression of the distinct sets of peptides encoded on the two transcripts and revealed the pattern of post‐translational processing of both protein precursors. From the gene sequence it was predicted that 16 final peptide products from the two precursor proteins could possibly exist. We showed that most of these peptides were indeed present in the identified neurons (13) while others were not (three), suggesting that not all of the potential cleavage sites within the two precursors are utilized. In this way, the neuronal expression of the full range of the peptide products resulting from alternative mRNA splicing was revealed for the first time.
Anatomical evidence for a mechanism of lateral inhibition in the rat thalamus
Authors: Pinault Didier , Deschênes Martin 
Published: March 2003

AbstractThe aim of this study was to determine whether or not thalamic reticular nucleus (Rt) neurons form synaptic connections with the thalamocortical (TC) neurons from which they receive synaptic contacts. Therefore, we examined, in adult rats, the relationships between single TC and Rt neurons, which had been marked simultaneously with an anterograde/retrograde tracer (biocytin or Neurobiotin), using the extracellular or juxtacellular technique. (i) From 30 successful extracellular microapplications of marker into the Rt, 22 gave retrogradely marked TC somatodendritic arbors at the fringe of or clear outside the anterogradely darkly stained Rt axon terminal fields. Following biocytin application into the thalamus, few cells were retrogradely stained in the Rt at the periphery of the anterogradely labelled axon terminal field. (ii) The juxtacellular filling of a single Rt cell was accompanied by the back‐filling of a single TC neuron (n = 4 pairs), which presumably formed synaptic contacts with the former cell. The somatodendritic complex of the back‐filled TC neuron was located outside the Rt cell's axonal arbor. These anatomical data provide clear evidence that Rt and thalamic neurons predominantly form between themselves open rather than closed loop connections. Because TC neurons make glutamatergic synapses onto Rt cells, which are GABAergic, and are the first elements synaptically activated by prethalamic afferents into the TC‐Rt network, the present results strongly support the hypothesis that Rt neurons principally generate a mechanism of lateral inhibition in the thalamus.
Identification of the reptilian basolateral amygdala: an anatomical investigation of the afferents to the posterior dorsal ventricular ridge of the lizard Podarcis hispanica
Authors: Lanuza Enrique , Belekhova Margarita , Martínez‐Marcos Alino , Font Cristian , Martínez‐García Fernando 
Published: March 2003

AbstractThe presence of multimodal association in the telencephalon of reptiles has been investigated by tracing the afferent connections to the posterior dorsal ventricular ridge (PDVR) of the lizard Podarcis hispanica. The PDVR receives telencephalic afferents from the lateral (olfactory) and dorsal cortices, and from the three unimodal areas of the anterior dorsal ventricular ridge, in a convergent manner. From the diencephalon, it receives afferents from the dorsomedial anterior and medial posterior thalamic nuclei, and from several hypothalamic nuclei. Brainstem afferents to the PDVR originate in the dorsal interpeduncular nucleus, the nucleus of the lateral lemniscus and parabrachial nucleus. The afferents to the thalamic nuclei that project to the PDVR have also been studied. The dorsomedial anterior thalamic nucleus receives projections mainly from limbic structures, whereas the medial posterior thalamic nucleus is the target of projections from structures with a clear sensory significance (optic tectum, torus semicircularis, nuclei of the lateral and spinal lemniscus, superior olive and trigeminal complex). As a result, the PDVR appears as an associative centre that receives visual, auditory, somatosensory and olfactory information from several telencephalic and non‐telencephalic centres, and a multimodal projection from the medial posterior thalamic nucleus. This pattern of afferents of the PDVR is similar to that of the caudal neostriatum in birds and the basolateral division of the mammalian amygdala. These results indicate that a multimodal amygdala is already present in reptiles, and has probably played a key role in the evolution of the vertebrate brain.
Structure and dynamics of receptive fields in the visual cortex of the cat (area 18) and the influence of GABAergic inhibition
Authors: Pernberg Joachim , Jirmann Kay‐Uwe , Eysel Ulf T. 
Published: March 2003

AbstractReceptive fields (RFs) in the visual cortex are characterized by spatiotemporal profiles that have been described in detail for area 17 simple cells. In this study, we analyse spatial and temporal RF properties of simple and complex cells in layer II/III of area 18 of the anaesthetized adult cat, using the reverse correlation method with brief 50 ms presentations of flashing bright and dark bars. Stimuli were presented with preferred orientation as previously determined by moving bars. Simple cell RFs were characterized by spatially and temporally separable ON and OFF subfields, while in complex cells ON and OFF subfields were superimposed. To discriminate possible contributions of GABAergic inhibition to RF structure and response dynamics in area 18, we have used three‐barrelled micropipettes for single cell recordings and microiontophoresis, and have documented ON and OFF responses before, during and after application of bicuculline methiodide for blockade of GABAA receptors. During blockade of GABAergic inhibition, the stimulus‐induced and resting discharge frequency increased, and in about 50% of the cells both ON and OFF subfields changed significantly in space and/or time in a reversible manner. In space, blockade of inhibition widened RF subfields, whereas in time, it shortened the duration of the excitatory cell response in simple and complex cells. ON and OFF subfields separated in space and time (simple cells), or time (complex cells) became less isolated or even superimposed. The results indicate substantial local inhibitory processing contributing to spatiotemporal RF properties in layers II/III of area 18 of the cat.
BDNF overexpression induces differential increases among subsets of sympathetic innervation in murine back skin
Authors: Botchkarev Vladimir A. , Botchkareva Natalia V. , Lommatzsch Marek , Peters Eva M. J. , Lewin Gary R. , Subramaniam Arun , Braun Armin , Renz Harald , Paus Ralf 
Published: March 2003

AbstractBesides their recognized dependence on nerve growth factor (NGF) during development, the dependence of mature sympathetic ganglion neurons on other neurotrophins is still unclear. Here, we have investigated the sympathetic innervation of back skin in mice overexpressing brain‐derived neurotrophic factor (BDNF) under the alpha‐myosin heavy‐chain promoter, as well as in BDNF knockout (–/–) mice. Compared with wild‐type controls, the dorsal skin of BDNF overexpressing mice displayed a significantly enhanced number of adrenergic, tyrosine hydroxylase‐immunoreactive (IR) nerve fibres, while cholinergic or peptidergic sensory nerve fibres appeared unaltered. The adrenergic hyperinnervation in dorsal skin of BDNF overexpressing mice was most pronounced in the arrector pili muscle of hair follicles, while no increase of tyrosine hydroxylase‐or neuropeptide Y‐IR fibres associated with subcutaneous blood vessels was found. Instead, back skin of BDNF knockout (–/–) mice contained significantly fewer tyrosine hydroxylase‐IR dermal nerve fibres than wild‐type animals. This suggests that BDNF plays an important role in the control of different subsets of adrenergic innervation in murine back skin, and indicates that paravertebral sympathetic ganglia display a previously unrecognized differential BDNF‐dependence in vivo.
Up‐ and down‐expression of the dopamine transporter by plasmid DNA transfer in the rat brain
Authors: Martres Marie‐Pascale , Demeneix Barbara , Hanoun Naïma , Hamon Michel , Giros Bruno 
Published: March 2003

AbstractThe functional role of the dopamine transporter (DAT) in central dopaminergic neurotransmission was assessed further by investigating the consequences on dopamine (DA) turn‐over of up‐ and down‐regulation of this protein induced by a non‐viral gene transfer approach. For this purpose, expression plasmids containing the sense or antisense coding sequence of DAT complexed with the cationic polymer, polyethylenimine (PEI), were injected into the rat substantia nigra, the brain region containing the majority of DA cell bodies. Before in vivo injection, the efficacies of the different DNA constructs were assessed by transfection studies into LLC‐PK1 cells. Stereotaxic administration of the sense plasmid complexed to PEI induced, 3 days later, a significant increase in the immunoautoradiographic labelling by anti‐DAT antibodies of the substantia nigra and various DA projection areas. These effects were associated with a significantly enhanced capacity of striatal synaptosomes to take up [3H]‐DA and lasted up to 14 days postinjection. In contrast, 7 days after intranigral administration of the antisense plasmid complexed to PEI, we observed a significant decrease of DAT immunolabelling in the substantia nigra and [3H]‐DA uptake by striatal synaptosomes. Whereas DA turnover in the striatum was unaltered 3 days after intranigral administration of the sense plasmid, it was increased 7 days after intranigral administration of the antisense construct. These data indicate that non‐viral transfer of the sense or antisense coding sequence of DAT can be used as a novel approach to induce long‐term changes in central DA neurotransmission.
Properties of bipolar VIPergic interneurons and their excitation by pyramidal neurons in the rat neocortex
Authors: Porter James T. , Cauli Bruno , Staiger Jochen F. , Lambolez Bertrand , Rossier Jean , Audinat Etienne 
Published: March 2003

AbstractIn the rat neocortex, a subset of GABAergic interneurons express the neuropeptide vasoactive intestinal peptide (VIP). Previously, we demonstrated that a population of VIPergic interneurons could be accurately identified by their irregular spiking (IS) pattern and their bipolar morphology. IS interneurons were studied in neocortical slices from 16–22‐day‐old rats using whole‐cell recordings, intracellular labelling and single‐cell RT‐PCR. In response to a depolarizing pulse, IS interneurons typically discharged a burst of action potentials followed by spikes emitted at an irregular frequency. Several seconds of depolarization, micromolar concentrations of 4‐aminopyridine, and nanomolar concentrations of either dendrotoxin I or K converted this irregular pattern to a sustained discharge, suggesting the involvement of an ID‐like K+ current. The main glutamate receptor subunits detected in IS cells were GluR1 flop and GluR2 flop, GluR5 and GluR6, and NR2B and NR2D for the α‐amino‐3‐hydroxyl‐5‐methyl‐4‐isoxazolepropionic acid (AMPA), kainate and N‐methyl‐d‐aspartic acid (NMDA) subtypes, respectively. Paired whole‐cell patch‐clamp recordings indicated that pyramidal neurons provide intracortical glutamatergic inputs onto IS interneurons. Most connections had high probabilities of response and exhibited frequency‐dependent paired pulse depression. Comparison of the amplitude distribution of paired responses suggested that most of these connections consisted of multiple functional release sites. Finally, two discrete subpopulations of IS cells could be identified based on the duration of the initial burst of action potentials and the differential expression of calretinin and choline acetyltransferase.
Drug‐induced reinstatement of heroin‐ and cocaine‐seeking behaviour following long‐term extinction is associated with expression of behavioural sensitization
Authors: De Vries Taco J. , Schoffelmeer Anton N. M. , Binnekade Rob , Mulder Arie H. , Vanderschuren Louk J. M. J. 
Published: March 2003

AbstractThe present study was designed to evaluate the relationship between reinstatement of drug‐seeking behaviour following long‐term extinction of intravenous (i.v.) drug self‐administration (an animal model for craving) and long‐term behavioural sensitization. Rats were allowed to self‐administer heroin (50 μg/kg per inj., 14 daily sessions), cocaine (500 μg/kg per inj., 10 daily sessions) or saline. Following a 3‐week extinction period, reinstatement tests were performed to evaluate priming effects of amphetamine, cocaine and heroin on non‐reinforced drug‐seeking behaviour. In addition, the occurrence of long‐term behavioural sensitization in rats with a history of heroin or cocaine self‐administration was determined. Heroin‐seeking behaviour was reinstated by heroin (0.25 mg/kg), amphetamine (1.0 mg/kg) and cocaine (10 mg/kg). In addition, animals with a history of heroin self‐administration displayed locomotor sensitization to both heroin and amphetamine. Cocaine‐seeking behaviour was reinstated by cocaine and amphetamine, but not by heroin. Interestingly, locomotor sensitization to amphetamine, but not heroin, was observed in animals with a history of cocaine self‐administration. In other words, the induction of drug‐seeking behaviour following a prolonged drug‐free period was found to be associated with the expression of long‐term behavioural sensitization. These data provide experimental evidence for a role of behavioural sensitization in the incentive motivation underlying drug‐seeking behaviour. If drug hyperresponsiveness would indeed be a crucial factor in drug‐induced craving in human addicts, pharmacological readjustment of the neuroadaptations underlying drug sensitization may prevent relapse to drug use long after detoxification.
Cultured oligodendrocyte progenitors derived from cerebral cortex express a glycine receptor which is pharmacologically distinct from the neuronal isoform
Authors: Belachew Shibeshih , Rogister Bernard , Rigo Jean‐Michel , Malgrange Brigitte , Mazy‐Servais Cécile , Xhauflaire Gaël , Coucke Paul , Moonen Gustave 
Published: March 2003

AbstractUsing the whole‐cell patch‐clamp technique, we demonstrate glycine‐induced currents in oligosphere‐derived oligodendrocyte progenitors cultured from newborn rats. Similar inward currents are also triggered by β‐alanine and taurine, two established glycine receptor agonists. In our recording conditions, glycine‐gated currents in oligodendrocyte progenitors reverse about 0 mV and are reversibly inhibited by the glycine competitive antagonist strychnine, the Cl–channel blocker picrotoxinin and the non‐competitive antagonist cyanotriphenylborate. The oligodendrocyte progenitors glycine receptor (GlyR) differs from the corresponding neuronal receptor: [3H]strychnine binding data and the strychnine inhibition curve of glycine‐induced currents in oligodendrocyte progenitor cultures suggest the existence of two strychnine binding sites on the oligodendroglial GlyR. Using total RNA isolated from oligodendrocyte progenitors cultures, reverse transcription–polymerase chain reaction analysis of glycine receptor subunit expression shows the presence of α2and β subunits and immunocytochemical stainings confirm that this GlyR contains an α subunit which is not α1. The molecular structure of the oligodendroglial GlyR could be either homopentameric α2or heteromeric α2β but in both cases, the sequence of the α2or β subunits have to be different from the known neuronal sequences in order to explain, respectively, the cyanotriphenylborate (α2) and picrotoxinin (β) sensitivities. This work thus demonstrates that GlyR are expressed by oligodendrocytes obtained not only from spinal cord but also from supraspinal structures. The pharmacological properties and presumably the molecular structure of oligodendroglial GlyR are original. The physiological meaning of the presence of such receptors on developing and mature oligodendrocytes remains unknown.
Nociceptive integration in the rat spinal cord: role of non‐linear membrane properties of deep dorsal horn neurons
Authors: Morisset Valérie , Nagy Frédéric 
Published: March 2003

AbstractDeep dorsal horn neurons (DHNs) involved in nociception can relay long‐lasting inputs and generate prolonged afterdischarges believed to enhance the transfer of nociceptive responses to the brain. We addressed the role of neuronal membrane properties in shaping these responses, by recording lamina V DHNs in a slice preparation of the rat cervical spinal cord. of 256 neurons, 102 produced accelerating discharges in response to depolarizing current pulses, whereas the other neurons showed spike frequency adaptation. Two mechanisms mediated the firing acceleration: a slow inactivation of a K+ current expressed upon activation of the neuron from hyperpolarized holding potentials, and the expression of a regenerative plateau potential activating around resting membrane potential. The increase in firing frequency was much stronger when sustained by the plateau potential (71 DHNs, 28%). A few neurons produced adaptation and both types of acceleration, in different membrane potential domains, showing that the firing pattern of a deep DHN is not a rigid characteristic. Plateau potentials could be elicited by stimulation of nociceptive primary afferent fibres. The bistability associated with plateau potentials permitted afterdischarges. Because plateau potentials had slow activation kinetics and were voltage‐dependent, the neurons had non‐linear input–output relationships in both the amplitude and time domains. Nociceptive primary afferent stimulation elicited intense and prolonged responses in plateau‐generating DHNs, while brief bursts of spikes were evoked otherwise. These results indicate that in a population of deep DHNs, intense firing and prolonged afterdischarges in response to nociceptive stimulation depend on non‐linear intrinsic membrane properties.