bluuebunny/crossref_metadata_2025_split huggingface dataset:
Localization of the A kinase anchoring protein AKAP79 in the human hippocampus
Authors: Sík Attila , Gulácsi Alexandra , Lai Yvonne , Doyle Werner K. , Pacia Stephan , Mody Istvan , Freund Tamás F. 
Published: March 2003

AbstractThe phosphorylation state of the proteins, regulated by phosphatases and kinases, plays an important role in signal transduction and long‐term changes in neuronal excitability. In neurons, cAMP‐dependent protein kinase (PKA), protein kinase C (PKC) and calcineurin (CN) are attached to a scaffold protein, A kinase anchoring protein (AKAP), thought to anchor these three enzymes to specific sites of action. However, the localization of AKAP, and the predicted sites of linked phosphatase and kinase activities, are still unknown at the fine structural level. In the present study, we investigated the distribution of AKAP79 in the hippocampus from postmortem human brains and lobectomy samples from patients with intractable epilepsy, using preembedding immunoperoxidase and immunogold histochemical methods. AKAP79 was found in the CA1, presubicular and subicular regions, mostly in pyramidal cell dendrites, whereas pyramidal cells in the CA3, CA2 regions and dentate granule cells were negative both in postmortem and in surgical samples. In some epileptic cases, the dentate molecular layer and hilar interneurons also became immunoreactive. At the subcellular level, AKAP79 immunoreactivity was present in postsynaptic profiles near, but not attached to, the postsynaptic density of asymmetrical (presumed excitatory) synapses. We conclude that the spatial selectivity for the action of certain kinases and phosphatases regulating various ligand‐ and voltage‐gated channels may be ensured by the selective presence of their anchoring protein, AKAP79, at the majority of glutamatergic synapses in the CA1, but not in the CA2/CA3 regions, suggesting profound differences in signal transduction and long‐term synaptic plasticity between these regions of the human hippocampus.
Expression of neuronal nitric oxide synthase/NADPH‐diaphorase during olfactory deafferentation and regeneration
Authors: Weruaga E. , Briñón J. G. , Porteros A. , Arévalo R. , Aijón J. , Alonso J. R. 
Published: March 2003

AbstractNeuronal nitric oxide synthase (nNOS) expression can be regulated under natural or experimental conditions. This work aims at elucidating whether the expression of nNOS or its related NADPH‐diaphorase (ND) activity are modified by manipulation of the normal inputs to neurons. We used the olfactory bulbs from two mouse strains, BALB and CD1, because they show divergences in their synapse patterns, and these differences affect periglomerular cells, interneurons expressing tyrosine hydroxylase or nNOS/ND. The olfactory inputs to these neurons can be disrupted by inhalation of methyl bromide. The effect of this gas on olfactory axons, as well as the synaptic features in both mouse strains, were studied using electron microscopy. The changes in expression were analysed qualitatively and quantitatively at different times after lesion to nine topographical regions of the olfactory bulb. Methyl bromide inhalation induced a degeneration of olfactory axons in both strains, but had different effects on the expression of nNOS/ND and tyrosine hydroxylase. In BALB mice, where periglomerular cells do not receive direct inputs from olfactory axons, no changes were detected in tyrosine hydroxylase or in ND expression. In CD1 periglomerular cells, where olfactory axons establish direct synapses, a significant down‐regulation of both markers was observed. These changes were observed differentially across the olfactory bulb, being more pronounced in rostral regions and more acute for ND than for tyrosine hydroxylase. Our results indicate that the synaptic inputs influence the expression of ND activity related to nNOS and that the activation of the enzyme is more severely affected than its protein expression.
MDMA (‘ecstasy’) enhances basal acetylcholine release in brain slices of the rat striatum
Authors: Fischer H. S. , Zernig G. , Schatz D. S. , Humpel C. , Saria A. 
Published: March 2003

AbstractThe pharmacological basis of acute (±)‐MDMA (3,4‐methylenedioxymethamphetamine) intoxication still awaits full characterization. According to present knowledge, MDMA enhances the release of serotonin and dopamine in striatal slices and interacts with different types of receptors such as 5‐HT2 (5‐hydroxytryptamine or serotonin), M1 and M2 muscarinic acetylcholine (ACh), and histamine H1 receptors. Currently, no information is available about the influence of (±)‐MDMA on striatal cholinergic neurotransmission. In the present study, we used the in vitro perfusion technique to investigate the effect of (±)‐MDMA on ACh release in rat striatal slices. Perfusions with (±)‐MDMA (10–300 μm) resulted in a dose‐dependent increase of spontaneous ACh release (EC50≈ 30 μm). The effect was reversible and Ca++‐ and tetrodotoxin‐sensitive. To determine the neurochemical pathways underlying this response, we perfused with (±)‐MDMA in the presence of various inhibitors of neurotransmitter receptors. Blockade of glutamate or muscarinic ACh receptors as well as 5‐HT1, 5‐HT2, 5‐HT3C or dopamine D2 receptors did not modulate (±)‐MDMA–induced ACh release. However, the presence of histamine H1 receptor antagonists in the perfusion medium abolished (±)‐MDMA‐induced ACh release. The present data clearly demonstrate that (±)‐MDMA enhances the activity of striatal cholinergic neurons and suggest an involvement of histamine H1 receptors. The effect is not mediated by glutamate and does not involve the activation of receptors of dopamine D2, 5‐HT1, 5‐HT2, 5‐HT3C or muscarinic ACh. Considering the relatively high affinity of (±)‐MDMA for the H1 histamine receptor (Ki 6 μm), a direct activation of this type of receptor might represent a plausible mechanism for (±)‐MDMA‐induced ACh release.
Peripheral but not central axotomy induces changes in Janus kinases (JAK) and signal transducers and activators of transcription (STAT)
Authors: Schwaiger Franz‐Werner , Schmitt Gerhard Hager andreas B. , Horvat Andrea , Hager Gundel , Streif Robert , Spitzer Christoph , Gamal Singer , Breuer Sebastian , Brook Gary A. , Nacimiento Wilhelm , Kreutzberg Georg W. 
Published: March 2003

AbstractNerve injury leads to the release of a number of cytokines which have been shown to play an important role in cellular activation after peripheral nerve injury. The members of the signal transducer and activator of transcription (STAT) gene family are the main mediators in the signal transduction pathway of cytokines. After phosphorylation, STAT proteins are transported into the nucleus and exhibit transcriptional activity. Following axotomy in rat regenerating facial and hypoglossal neurons, a transient increase of mRNA for JAK2, JAK3, STAT1, STAT3 and STAT5 was detected using in situ hybridization and semi‐quantitative polymerase chain reaction (PCR). Of the investigated STAT molecules, only STAT3 protein was significantly increased. In addition, activation of STAT3 by phosphorylation on position Tyr705 and enhanced nuclear translocation was found within 3 h in neurons and after 1 day in astrocytes. Unexpectedly, STAT3 tyrosine phosphorylation was obvious for more than 3 months. In contrast, none of these changes was found in response to axotomy of non‐regenerating Clarke's nucleus neurons, although all the investigated models express c‐Jun and growth‐associated protein‐43 (GAP‐43) in response to axonal injury. Increased expression of Janus kinase (JAK) and STAT molecules after peripheral nerve transection suggests changes in the responsiveness of the neurons to signalling molecules. STAT3 as a transcription factor, which is expressed early and is activated persistently until the time of reinnervation, might be involved in the switch from the physiological gene expression to an ‘alternative program’ activated only after peripheral nerve injury.
Differential c‐fos expression in the rhinencephalon and striatum after enhanced sleep–wake states in the cat
Authors: Sastre J. P. , Buda C. , Lin J. S. , Jouvet M. 
Published: March 2003

AbstractIn order to delimit the supra‐brainstem structures that are activated during the sleep–waking cycle, we have examined c‐fos immunoreactivity in four groups of polygraphically recorded cats killed after 3 h of prolonged waking (W), slow‐wave sleep (SWS), or paradoxical sleep (PS), following microinjection of muscimol (a γ‐aminobutyric acid, GABA agonist) into the periaqueductal grey matter and adjacent areas [Sastre et al. (1996), Neuroscience, 74, 415–426]. Our results demonstrate that there was a direct relationship between a significant increase in c‐fos labelling and the amount of PS in the laterodorsalis tegmenti in the pons, supramamillary nucleus, septum, hippocampus, gyrus cingulate, amygdala, stria terminalis and the accumbens nuclei. Moreover, in all these structures, the number of Fos‐like immunoreactive neurons in the PS group was significantly higher (three to 30‐fold) than in the SWS and W groups. We suggest that the dense expression of the immediate‐early gene c‐fos in the rhinencephalon and striatum may be considered as a tonic component of PS at the molecular level and that, during PS, the rhinencephalon and striatum are the main targets of an excitatory system originating in the pons.
The serotonin 5‐HT2 receptor–phospholipase C system inhibits the induction of long‐term potentiation in the rat visual cortex
Authors: Edagawa Yoshikuni , Saito Hiroshi , Abe Kazuho 
Published: March 2003

AbstractThe effect of serotonin 5‐HT2 receptor stimulation on long‐term potentiation (LTP) in the primary visual cortex was investigated by using rat brain slices in vitro. Field potentials evoked by stimulation of layer IV were recorded in layer II/III. The 5‐HT2 receptor agonist 1‐(2,5‐dimethyl‐4‐iodophenyl)‐2‐aminopropane (DOI) did not affect baseline synaptic potentials evoked by single‐pulse test stimulation, but significantly inhibited the induction of LTP in a concentration‐dependent manner (0.1–10 μm). The LTP‐inhibiting effect of DOI (10 μm) was blocked by the 5‐HT2,7 receptor antagonist ritanserin (10 μm), but not by the 5‐HT1A receptor antagonist NAN‐190 (10 μm) nor by the 5‐HT3,4 receptor antagonist MDL72222 (10 μm). The inhibitory effect of DOI was also blocked by the phospholipase C inhibitor U73122, but not by its inactive analogue U73343. These results suggest that visual cortex LTP is inhibited by activation of the 5‐HT2 receptor–phospholipase C system. In addition, the LTP‐inhibiting effect of DOI was abolished by the presence of the GABAA receptor antagonist bicuculline (10 μm), suggesting that 5‐HT2 receptor‐mediated inhibition of visual cortex LTP is dependent on GABAergic inhibition.
The distribution of the mRNA and protein products of the melanin‐concentrating hormone (MCH) receptor gene, slc‐1, in the central nervous system of the rat
Authors: Hervieu G. J. , Cluderay J. E. , Harrison D. , Meakin J. , Maycox P. , Nasir S. , Leslie R. A. 
Published: March 2003

AbstractMelanin‐concentrating hormone (MCH), a 19 amino acid cyclic peptide, is largely expressed in the hypothalamus. It is implicated in the control of general arousal and goal‐orientated behaviours in mammals, and appears to be a key messenger in the regulation of food intake. An understanding of the biological actions of MCH has been so far hampered by the lack of information about its receptor(s) and their location in the brain. We recently identified the orphan G‐protein‐coupled receptor SLC‐1 as a receptor for the neuropeptide MCH. We used in situ hybridization histochemistry and immunohistochemistry to determine the distribution of SLC‐1 mRNA and its protein product in the rat brain and spinal cord. SLC‐1 mRNA and protein were found to be widely and strongly expressed throughout the brain. Immunoreactivity was observed in areas that largely overlapped with regions mapping positive for mRNA. SLC‐1 signals were observed in the cerebral cortex, caudate‐putamen, hippocampal formation, amygdala, hypothalamus and thalamus, as well as in various nuclei of the mesencephalon and rhombencephalon. The distribution of the receptor mRNA and immunolabelling was in good general agreement with the previously reported distribution of MCH itself. Our data are consistent with the known biological effects of MCH in the brain, e.g. modulation of the stress response, sexual behaviour, anxiety, learning, seizure production, grooming and sensory gating, and with a role for SLC‐1 in mediating these physiological actions.
Acetylcholine stimulates cortical precursor cell proliferation in vitro via muscarinic receptor activation and MAP kinase phosphorylation
Authors: Ma Wu , Maric Dragan , Li Bing‐sheng , Hu Qian , Andreadis Joanne D. , Grant Geraldine M. , Liu Qi‐Ying , Shaffer Kara M. , Chang Yoong H. , Zhang Lei , Pancrazio Joseph J. , Pant Harish C. , Stenger David A. , Barker Jeffery L. 
Published: March 2003

AbstractIncreasing evidence has shown that some neurotransmitters act as growth‐regulatory signals during brain development. Here we report a role for the classical neurotransmitter acetylcholine (ACh) to stimulate proliferation of neural stem cells and stem cell‐derived progenitor cells during neural cell lineage progression in vitro. Neuroepithelial cells in the ventricular zone of the embryonic rat cortex were found to express the m2 subtype of the muscarinic receptor. Neural precursor cells dissociated from the embryonic rat cortical neuroepithelium were expanded in culture with basic fibroblast growth factor (bFGF). reverse transcriptase‐polymerase chain reaction (RT‐PCR) revealed the presence of m2, m3 and m4 muscarinic receptor subtype transcripts, while immunocytochemistry demonstrated m2 protein. ACh and carbachol induced an increase in cytosolic Ca2+ and membrane currents in proliferating (BrdU+) cells, both of which were abolished by atropine. Exposure of bFGF‐deprived precursor cells to muscarinic agonists not only increased both cell number and DNA synthesis, but also enhanced differentiation of neurons. These effects were blocked by atropine, indicating the involvement of muscarinic ACh receptors. The growth‐stimulating effects were also antagonized by a panel of inhibitors of second messengers, including 1,2‐bis‐(O‐aminophenoxy)‐ethane‐N,N,N′,N′‐tetraacetic acid (BAPTA‐AM) to chelate cytosolic Ca2+, EGTA to complex extracellular Ca2+, pertussis toxin, which uncouples certain G‐proteins, the protein kinase C inhibitor H7 and the mitogen‐activated protein kinase (MAPK) inhibitor PD98059. Muscarinic agonists activated MAPK, which was significantly inhibited by atropine and the same panel of inhibitors. Thus, muscarinic receptors expressed by neural precursors transduce a growth‐regulatory signal during neurogenesis via pathways involving pertussis toxin‐sensitive G‐proteins, Ca2+ signalling, protein kinase C activation, MAPK phosphorylation and DNA synthesis.
Interleukin‐6 inhibits neurotransmitter release and the spread of excitation in the rat cerebral cortex
Authors: D'arcangelo Giovanna , Tancredi Virginia , Onofri Franco , D'antuono Margherita , Giovedì Silvia , Benfenati Fabio 
Published: March 2003

AbstractCytokines are extracellular mediators that have been reported to affect neurotransmitter release and synaptic plasticity phenomena when applied in vitro. Most of these effects occur rapidly after the application of the cytokines and are presumably mediated through the activation of protein phosphorylation processes. While many cytokines have an inflammatory action, interleukin‐6 (IL‐6) has been found to have a neuroprotective effect against ischaemia lesions and glutamate excitotoxicity, and to increase neuronal survival in a variety of experimental conditions. In this paper, the functional effects of IL‐6 on the spread of excitation visualized by dark‐field/infrared videomicroscopy in rat cortical slices and on glutamate release from cortical synaptosomes were analysed and correlated with the activation of the STAT3, mitogen‐activated protein kinase ERK (MAPK/ERK) and stress‐activated protein kinase/cJun NH2‐terminal kinase (SAPK/JNK) pathways. We have found that IL‐6 depresses the spread of excitation and evoked glutamate release in the cerebral cortex, and that these effects are accompanied by a stimulation of STAT3 tyrosine phosphorylation, an inhibition of MAPK/ERK activity, a decreased phosphorylation of the presynaptic MAPK/ERK substrate synapsin I and no detectable effects on SAPK/JNK. The effects of IL‐6 were effectively counteracted by treatment of the cortical slices with the tyrosine kinase inhibitor lavendustin A. The inhibitory effects of IL‐6 on glutamate release and on the spread of excitation in the rat cerebral cortex indicate that the protective effect of IL‐6 on neuronal survival could be mediated by a downregulation of neuronal activity, release of excitatory neurotransmitters and MAPK/ERK activity.
Dynorphins directly inhibit neuronal nicotinic acetylcholine receptors in PC12 cells
Authors: Itoh Hideki , Andoh Tomio , Watanabe Itaru , Sasaki Tosio , Kamiya Yoshinori , Okumura Fukuichiro 
Published: March 2003

AbstractThe authors have previously reported that dynorphin A (1–17), an endogenous kappa opioid agonist, inhibits the current mediated through neuronal nicotinic acetylcholine receptors (nAChRs) without the involvement of opioid receptors or G‐proteins. We have further characterized this action to elucidate the mechanisms. The nicotine‐induced current was studied in PC12 cells using patch‐clamp techniques. In the whole‐cell configuration, four kinds of dynorphins with different lengths, dynorphin A (1–17) (1–13) (2–13) and (1–8), similarly inhibited the nicotine‐induced inward current at 1 μm and accelerated the current decay. The inhibition by dynorphin A (1–17) was not antagonized by the increasing concentrations of nicotine. The current–voltage relationship revealed that dynorphin's inhibition was voltage independent at the membrane potentials from −30 to −70 mV. The inhibition was not affected by pretreatment with pertussis toxin (PTX) or inclusion of staurosporine into the pipette solution. The inhibitory effect of dynorphin A (1–17) was well preserved in the outside‐out patch configuration. Analysis of the nicotine‐induced noise and single‐channel kinetics revealed that dynorphin A(1–17) reduced open time without changing the amplitude of the unitary current. We found that the inhibitory effect on neuronal nAChRs is shared by all four dynorphins studied. The inhibition appears to be non‐competitive and voltage independent. The outside‐out recording together with other experiments indicated that a major part of this inhibition is not mediated through cytoplasmic messengers, but based on the direct action of dynorphins on neuronal nAChRs leading to the reduction of open time.
Synaptotagmin I and IV define distinct populations of neuronal transport vesicles
Authors: Berton Frédérique , Cornet Véronique , Iborra Cécile , Garrido Juan , Dargent Bénédicte , Fukuda Mitsunori , Seagar Michael , Marquèze Béatrice 
Published: March 2003

AbstractMammalian synaptotagmins constitute a multigene family of at least 11 membrane proteins. We have characterized synaptotagmin IV using antibodies directed against the C2A domain of the protein. Antibodies reacted specifically with a protein band that migrated as a 41–44 kDa doublet. Synaptotagmin IV expression was regulated throughout development. A strong decrease in the amount detected by Western blotting occurred between postnatal day 5 and adulthood, in agreement with studies on the expression of synaptotagmin IV transcripts. In subcellular fractionation, synaptotagmin IV was not detected in the synaptic vesicle‐enriched fraction. Immunofluorescence microscopy was concordant with this finding. In 6‐day‐old rat cerebellum and cultured hippocampal neurons the subcellular distribution of synaptotagmin IV was clearly different from that of synaptotagmin I. Synaptotagmin IV displayed a punctate non‐polarized distribution on neuronal extensions, whereas synaptotagmin I staining was essentially synaptic. Synaptotagmin IV staining was also observed in the soma in strong perinuclear fluorescent puncta superimposed on that of Golgi/TGN markers. Furthermore, synaptotagmin IV was seen in the proximal part of the growth cone domain and not in the microfilament‐rich region which includes filopodia. Co‐localizations with the adhesion molecules vinculin and zyxin at the proximal part of growth cones were observed. Synaptotagmin IV may thus be involved in the regulation of specific membrane‐trafficking pathways during brain development.
Trk B signalling controls LTP but not LTD expression in the developing rat visual cortex
Authors: Sermasi Edoardo , Margotti Elisa , Cattaneo Antonino , Domenici Luciano 
Published: March 2003

AbstractNeurotrophins have been suggested to act as liaison molecules between activity‐dependent synaptic plasticity and the establishment of patterns of synaptic connectivity during postnatal developmental in different brain areas, including the visual cortex. In particular, recent studies have shown that Trk B ligands are involved in the formation of the ocular dominance columns during postnatal development. Here, we examined the contribution of endogenous Trk B activation to the regulation of different forms of synaptic plasticity including long‐term potentiation (LTP), long‐term depression (LTD) and LTP after LTD in the developing visual cortex. Rat cortical slices were incubated with a soluble form of Trk B receptor (TrkB IgG) preventing Trk B activation by endogenous ligands. LTP expression was also studied at P23 (postnatal), when the expression of brain‐derived neurotrophic factor (BDNF) reaches a peak and the LTP expression is normally downregulated. The present results demonstrate that Trk B activation is required for the long‐term maintenance, > 30 min, of both LTP and LTP after LTD at P17. At P23, a higher concentration of TrkB IgG was necessary to impair LTP. In contrast, neither amplitude nor duration of LTD were affected by Trk B ligands blockade. Taken together, these results indicate that endogenous Trk B ligands are necessary for the expression of LTP but not LTD at a critical time during postnatal cortical development.
Free radical production correlates with cell death in an in vitro model of epilepsy
Authors: Frantseva Marina V. , Velazquez Jose L. Perez , Hwang Paul A. , Carlen Peter L. 
Published: March 2003

AbstractFree radical (FR) production, a major step in calcium‐dependent neurodegeneration, has been linked to the generation of epileptiform activity and seizure‐induced cell death. However, direct evidence of FR production in neurons during seizures has never been presented. Using hippocampal cultured slices we demonstrate that FRs are produced in CA3 but not CA1 pyramidal neurons during the rhythmic synchronous activity induced by the GABAA receptor antagonist bicuculline. The production of FRs (measured as changes in the fluorescence emission of dihydrorhodamine 123) was correlated with an increase in the baseline levels of intracellular calcium ([Ca2+]i) estimated by fluo‐3 injected into individual neurons via a patch pipette. [Ca2+]i increased during spike bursting and returned to baseline levels after the burst termination in CA1, but not in CA3, pyramidal neurons where ‘interburst’ calcium concentrations progressively increased. Measurement of cell death, performed with propidium iodide 48 h after a 30‐min exposure to bicuculline, revealed most prominent degeneration of pyramidal neurons in the CA3 pyramidal layer. The FR scavengers vitamin E and glutathione significantly reduced the seizure‐induced neurodegeneration without supressing spontaneous epileptiform activity. These observations indicate that FR overproduction is related to seizure‐induced neuronal death.