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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 70 (1998), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Findings in vivo and in culture suggest that neuronal activity selectively regulates GABAA receptor δ subunit mRNA expression in cerebellar granule neurons. For example, the onset of δ subunit mRNA expression during postnatal maturation coincides with innervation. Furthermore, depolarizing conditions (25 mM KCl) in culture initiate and maintain increases in the δ subunit transcript level. We have now examined whether similar changes in δ subunit mRNA expression occur in cultured neurons after activation of glutamate receptors of the NMDA subtype, an event that mimics granule neuron depolarization by mossy fiber innervation in vivo. Our studies demonstrate that addition of 50 µM NMDA to cultured rat granule neurons maintained in defined, serum-free medium specifically initiates δ subunit transcript expression. Whereas the level of the δ subunit mRNA is increased fourfold by this treatment, levels of other GABAA receptor subunit transcripts are not significantly changed. The level of the δ subunit transcript is further increased when NMDA receptor activation is enhanced by maintaining neurons in a Mg2+-free medium to alleviate Mg2+ blockade of the receptor channel. The NMDA-induced elevation in δ subunit transcript expression involves activation of a Ca2+/calmodulin-dependent protein kinase pathway. These findings suggest that activation of an excitatory pathway may regulate the expression of an inhibitory receptor phenotype in cerebellar granule neurons in vivo.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 90 (2004), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The GABAA receptor β subunit is required to confer sensitivity to γ-aminobutyric acid (GABA), the major inhibitory neurotransmitter in the CNS. In previous studies we demonstrated that the growth and differentiation factor neuregulin 1 (NRG1) selectively induced expression of the β2 subunit mRNA and encoded protein in rat cerebellar granule neurons in culture. In the present report we examine the signaling pathways that mediate this effect. These studies demonstrate that the effects of NRG1 on β2 subunit polypeptide expression require activation of the ErbB4 receptor tyrosine kinase; its effects are inhibited by pharmacological blockade of ErbB4 phosphorylation or reduction of receptor level with an antisense oligodeoxynucleotide. The NRG1-induced activation of ErbB4 stimulates the mitogen-activated protein kinase (MAPK), phosphatidylinositol 3-kinase (PI3K) and cyclin-dependent kinase-5 (cdk5) pathways. Pharmacological blockade of any of these pathways inhibits increased β2 subunit expression, demonstrating that all three pathways are required to mediate the effects of NRG1 on GABAA receptor subunit expression in cerebellar granule neurons. These studies provide novel information concerning the actions of NRG1 on GABAA receptor expression in the CNS.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 1267-1274 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A microprocessor-controlled system has been developed to automatically scan tissue culture dishes in order to detect and locate fluorescently labeled cell colonies for subsequent cloning. An X-Y recorder mechanism moves an 80-mm-diam dish in a raster scan through a stationary laser beam adjacent to a photomultiplier tube equipped with an emission filter. Front-end electronics processes the PMT signal to screen out small-scale fluorescent artifacts of selectable size (e.g., 〈0.2 mm). Appropriate signals are input to the computer which then interrupts the raster scan to perform a limited fine scan of the dish to accurately localize the fluorescent spot position. An additional artifact test using a different filter is then performed. The underside of the dish is scribed at the location of spots that pass this test. Using fluorescein as a label, fluorescence as low as 25% above intrinsic cell background fluorescence can be detected. The fluorescence signal level threshhold can be set (e.g., 70% above intrinsic cell background) to within an accuracy of approximately 15% of intrinsic cell background fluorescence, and the system will reliably find colonies with a signal exceeding that level. With the above typical values, the number of false positives is typically less than five per dish and the time to completely scan an 80-mm-diam tissue culture dish is 2–4 min.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: GABAA receptors in the CNS are pentameric molecules composed of α, β, γ, δ, ε and θ subunits. Studies on transfected cells have shown that GABAA receptor β subunit isoforms can direct α1 subunit localization within the cell. To examine the role of selected subunits in governing GABAA receptor expression in neurons, cultures of rat cerebellar granule cells were grown with antisense or sense oligodeoxynucleotides (ODNs) specific for the α1, β2 or γ2 subunits. These subunits are all expressed in granule neurons where they are thought to contribute to an abundant receptor type. Following ODN treatment, subunit expression and distribution were examined by western blotting, immunocytochemistry and RT-PCR. Treatment of the cultures with the antisense, but not the corresponding sense, ODNs reduced the levels of the targeted subunit polypeptides. In addition, the β2 antisense ODN reduced the level of the α1 subunit polypeptide without altering the level of its mRNA. In contrast, treatment with the β2 subunit antisense ODN did not alter γ2 subunit polypeptide expression, distribution or mRNA level. These findings suggest that the α1 subunit requires a β subunit for assembly into GABAA receptors in cerebellar granule neurons.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 493 (1987), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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