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Hippocampal Neurones (hippocampal + neurone)
Selected AbstractsNeurone-to-astrocyte communication by endogenous ATP in mixed culture of rat hippocampal neurones and astrocytesDRUG DEVELOPMENT RESEARCH, Issue 1 2003Schuichi Koizumi ATP is recognized as an important intercellular signaling molecule in the peripheral and CNS. Glutamate is reported to be an important neurone-to-glia mediator being released from neurones and astrocytes that activates astrocytic and neuronal Ca2+ responses, respectively. We demonstrate here that endogenous ATP could be an extracellular molecule for neurone-to-astrocyte communication in cocultured rat hippocampal neurones and astrocytes. Hippocampal neurones reveal synchronized Ca2+ oscillation, which was due to glutamatergic synaptic transmission. When analyzed in a fura-2 method, a slight and very slow increase in intracellular Ca2+ concentration ([Ca2+]i) elevation was observed in some population of astrocytes. Such astrocytic [Ca2+]i elevation was dramatically inhibited by apyrase, though apyrase itself had no effect on neuronal Ca2+ oscillation. For a detail analysis, we investigated changes in [Ca2+]i in cells using a confocal microscopy. When cocultured hippocampal neurones and astrocytes were depolarized electronically in the presence of glutamate-receptor antagonists, a transient elevation in [Ca2+]i was observed in neurones, which was followed by a slowly initiated and small rise in [Ca2+]i in astrocytes. Apyrase or P2 receptor antagonists almost abolished the [Ca2+]i rises in astrocytes, suggesting that depolarization-evoked ATP release from neurones should produce astrocytic [Ca2+]i elevation via P2 receptors. Using a luciferin,luciferase bioluminescence assay, we found that neurones could release ATP in an activity-dependent manner. These findings suggest that endogenous ATP should be an important intercellular mediator between neurones and astrocytes and that functions of these cells should be fine-tuned by endogenously released ATP in situ. Drug Dev. Res. 59:88,94, 2003. © 2003 Wiley-Liss, Inc. [source] Long-term depression activates transcription of immediate early transcription factor genes: involvement of serum response factor/Elk-1EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2006Antje Lindecke Abstract Long-term depression (LTD) is one of the paradigms used in vivo or ex vivo for studying memory formation. In order to identify genes with potential relevance for memory formation we used mouse organotypic hippocampal slice cultures in which chemical LTD was induced by applications of 3,5-dihydroxyphenylglycine (DHPG). The induction of chemical LTD was robust, as monitored electrophysiologically. Gene expression analysis after chemical LTD induction was performed using cDNA microarrays containing >7000 probes. The DHPG-induced expression of immediate early genes (c-fos, junB, egr1 and nr4a1) was subsequently verified by TaqMan polymerase chain reaction. Bioinformatic analysis suggested a common regulator element [serum response factor (SRF)/Elk-1 binding sites] within the promoter region of these genes. Indeed, here we could show a DHPG-dependent binding of SRF at the SRF response element (SRE) site within the promoter region of c-fos and junB. However, SRF binding to egr1 promoter sites was constitutive. The phosphorylation of the ternary complex factor Elk-1 and its localization in the nucleus of hippocampal neurones after DHPG treatment was shown by immunofluorescence using a phosphospecific antibody. We suggest that LTD leads to SRF/Elk-1-regulated gene expression of immediate early transcription factors, which could in turn promote a second broader wave of gene expression. [source] Identification of a cis -acting element required for dendritic targeting of activity-regulated cytoskeleton-associated protein mRNAEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2005Hiroaki Kobayashi Abstract The mRNA encoding activity-regulated cytoskeleton-associated protein (Arc) is known to be targeted to dendritic regions that have received strong synaptic inputs. However, the cis- acting elements in Arc mRNA that mediate dendritic targeting have not been identified. To identify the dendritic targeting element (DTE) in rat Arc mRNA, we expressed reporter mRNAs containing various regions of Arc in primary hippocampal neurones and analysed their subcellular distribution by in situ hybridization. Here, we report that the 3,-untranslated region of rat Arc mRNA contains a 350-nucleotide DTE with strong dendritic targeting activity and another 370-nucleotide sequence with weaker dendritic targeting activity. The 350-nucleotide DTE does not share any obvious sequence similarity with other known DTEs previously reported. [source] CAST2: identification and characterization of a protein structurally related to the presynaptic cytomatrix protein CASTGENES TO CELLS, Issue 1 2004Maki Deguchi-Tawarada The cytomatrix at the active zone (CAZ) is thought to define the site of Ca2+ -dependent exocytosis of neurotransmitters. We have recently identified a novel CAZ protein from rat brain which we have named CAST (CAZ-associated structural protein). CAST forms a large molecular complex with other CAZ proteins such as Bassoon, RIM1 and Munc13-1, at least through direct binding to RIM1. Here, we have identified a rat protein that is structurally related to CAST and named it CAST2. Subcellular fractionation analysis of rat brain shows that CAST2 is also tightly associated with the postsynaptic density fraction. Like CAST, CAST2 directly binds RIM1 and forms a hetero-oligomer with CAST. In primary cultured rat hippocampal neurones, CAST2 co-localizes with Bassoon at synapses. Furthermore, immunoelectron microscopy reveals that CAST2 localizes to the vicinity of the presynaptic membrane of synapses in mouse brain. Sequence analysis reveals that CAST2 is a rat orthologue of the human protein ELKS. ELKS has also recently been identified as Rab6IP2 and ERC1. Accordingly, the original CAST is tentatively re-named CAST1. These results indicate that CAST2 is a new component of the CAZ and, together with CAST1, may be involved in the formation of the CAZ structure. [source] Chronic lithium administration to FTDP-17 tau and GSK-3, overexpressing mice prevents tau hyperphosphorylation and neurofibrillary tangle formation, but pre-formed neurofibrillary tangles do not revertJOURNAL OF NEUROCHEMISTRY, Issue 6 2006Tobias Engel Abstract Glycogen synthase kinase-3 (GSK-3) has been proposed as the main kinase able to aberrantly phosphorylate tau in Alzheimer's disease (AD) and related tauopathies, raising the possibility of designing novel therapeutic interventions for AD based on GSK-3 inhibition. Lithium, a widely used drug for affective disorders, inhibits GSK-3 at therapeutically relevant concentrations. Therefore, it was of great interest to test the possible protective effects of lithium in an AD animal model based on GSK-3 overexpression. We had previously generated a double transgenic model, overexpressing GSK-3, in a conditional manner, using the Tet-off system and tau protein carrying a triple FTDP-17 (frontotemporal dementia and parkinsonism linked to chromosome 17) mutation. This transgenic line shows tau hyperphosphorylation in hippocampal neurones accompanied by neurofibrillary tangles (NFTs). We used this transgenic model to address two issues: first, whether chronic lithium treatment is able to prevent the formation of aberrant tau aggregates that result from the overexpression of FTDP-17 tau and GSK-3,; second, whether lithium is able to change back already formed NFTs in aged animals. Our data suggest that progression of the tauopathy can be prevented by administration of lithium when the first signs of neuropathology appear. Furthermore, it is still possible to partially reverse tau pathology in advanced stages of the disease, although NFT-like structures cannot be changed. The same results were obtained after shut-down of GSK-3, overexpression, supporting the possibility that GSK-3 inhibition is not sufficient to reverse NFT-like aggregates. [source] Reduced rates of axonal and dendritic growth in embryonic hippocampal neurones cultured from a mouse model of Sandhoff diseaseNEUROPATHOLOGY & APPLIED NEUROBIOLOGY, Issue 4 2003D. Pelled Sandhoff disease is a lysosomal storage disease in which ganglioside GM2 accumulates because of a defective ,-subunit of ,-hexosaminidase. This disease is characterized by neurological manifestations, although the pathogenic mechanisms leading from GM2 accumulation to neuropathology are largely unknown. We now examine the viability, development and rates of neurite growth of embryonic hippocampal neurones cultured from a mouse model of Sandhoff disease, the Hexb,/, mouse. GM2 was detected by metabolic labelling at low levels in wild type (Hexb+/+) neurones, and increased by approximately three-fold in Hexb,/, neurones. Hexb,/, hippocampal neurones were as viable as their wild type counterparts and, moreover, their developmental programme was unaltered because the formation of axons and of the minor processes which eventually become dendrites was similar in Hexb,/, and Hexb+/+ neurones. In contrast, once formed, a striking difference in the rate of axonal and minor process growth was observed, with changes becoming apparent after 3 days in culture and highly significant after 5 days in culture. Analysis of various parameters of axonal growth suggested that a key reason for the decreased rate of axonal growth was because of a decrease in the formation of collateral axonal branches, the major mechanism by which hippocampal axons elongate in culture. Thus, although the developmental programme with respect to axon and minor process formation and the viability of hippocampal neurones are unaltered, a significant decrease occurs in the rate of axonal and minor process growth in Hexb,/, neurones. These results appear to be in contrast to dorsal root ganglion neurones cultured from 1-month-old Sandhoff mice, in which cell survival is impaired but normal outgrowth of neurones occurs. The possible reasons for these differences are discussed. [source] | |||||||||||||