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  • 1
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    Delayed myelination in a mouse model of fragile X syndrome (2013)
    Oxford University Press
    Details
    Publication Date: 2013-09-08
    Description: Fragile X Syndrome is the most common inherited cause of autism. Fragile X mental retardation protein (FMRP), which is absent in fragile X, is an mRNA binding protein that regulates the translation of hundreds of different mRNA transcripts. In the adult brain, FMRP is expressed primarily in the neurons; however, it is also expressed in developing glial cells, where its function is not well understood. Here, we show that fragile X (Fmr1) knockout mice display abnormalities in the myelination of cerebellar axons as early as the first postnatal week, corresponding roughly to the equivalent time in human brain development when symptoms of the syndrome first become apparent (1–3 years of age). At postnatal day (PND) 7, diffusion tensor magnetic resonance imaging showed reduced volume of the Fmr1 cerebellum compared with wild-type mice, concomitant with an 80–85% reduction in the expression of myelin basic protein, fewer myelinated axons and reduced thickness of myelin sheaths, as measured by electron microscopy. Both the expression of the proteoglycan NG2 and the number of PDGFRα+/NG2+ oligodendrocyte precursor cells were reduced in the Fmr1 cerebellum at PND 7. Although myelin proteins were still depressed at PND 15, they regained wild-type levels by PND 30. These findings suggest that impaired maturation or function of oligodendrocyte precursor cells induces delayed myelination in the Fmr1 mouse brain. Our results bolster an emerging recognition that white matter abnormalities in early postnatal brain development represent an underlying neurological deficit in Fragile X syndrome.
    Print ISSN: 0964-6906
    Electronic ISSN: 1460-2083
    Topics: Biology , Medicine
    Published by Oxford University Press
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  • 2
    Electronic Resource
    Electronic Resource
    A Comparison of Two Alternatively Spliced Forms of a Metabotropic Glutamate Receptor Coupled to Phosphoinositide Turnover (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 61 (1993), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: A comparison of the pharmacological and physiological properties of the metabotropic glutamate 1α and 1β receptors (mGluR1α and mGluR1β) expressed in baby hamster kidney (BHK 570) cells was performed. The mGluR1β receptor is an alternatively spliced form of mGluR1α with a modified carboxy terminus. Immunoblots of membranes from the two cell lines probed with receptor-specific antipeptide antibodies showed that mGluRIa migrated with an Mr= 154, 000, whereas mGluR1β migrated with an Mr= 96, 000. Immunofluorescence imaging of receptors expressed in BHK 570 cells revealed that the mGluR1α receptor was localized to patches along the plasmalemma and on intracellular membranes surrounding the nucleus, whereas mGluR1β was distributed diffusely throughout the cell. Agonist activation of the mGluR1α and the mGluR1β receptors stimulated phosphoinositide hydrolysis. At both receptors, glutamate, quisqualate, and ibotenate were full agonists, whereas trans-(+)-1-aminocyclopentane-1, 3-dicarboxylate appeared to act as a partial agonist. The stimulation of phosphoinositide hydrolysis by mGluR1α showed pertussis toxin-sensitive and insensitive components, whereas the mGluR1β response displayed only the toxin-insensitive component. The mGluR1α and mGluR1β receptors also increased intracellular calcium levels by inducing release from intracellular stores. These results indicate that the different carboxy terminal sequences of the two receptors directly influences G protein coupling and subcellular deposition of the receptor polypeptides and suggest that the two receptors may subserve different roles in the nervous system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1993.tb03540.x
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  • 3
    Electronic Resource
    Electronic Resource
    Solubilization of Kainic Acid Binding Sites from Rat Brain (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 49 (1987), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Kainic acid binding sites were solubilized from rat brain using a combination of Triton X-100 and digitonin. The highest percentage of solubilized binding sites (45%) was obtained by treating brain membranes with 1 % Triton-X-100 and 0.2% digitonin in 0.5 M potassium phosphate containing 20% glycerol. The solubilized binding sites were stable and amenable to analysis by gel nitration and lectin affinity chromatography. Computer assisted analyses demonstrated that the solubilized sites displayed high-and low-affinity binding constants similar to the membrane-bound sites. Competition experiments further supported the pharmacological similarities of the solubilized and membrane-bound sites. Gel nitration chromatography of the solubilized binding site indicated that the detergent-bound complex had a Stokes radius of 82.7 A. The [3H]kainic acid binding site appears to be glycosylated based on its capability to bind to lectins. The lectin, wheat-germ agglutinin, proved to be a potentially useful tool for characterization because the solubilized binding sites were bound and eluted in relatively high yield.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1987.tb10012.x
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  • 4
    Electronic Resource
    Electronic Resource
    Detection and quantitation of a ring-hydroxylated metabolite of the antidepressant drug tranylcypromine (1986)
    Springer
    Journal of neural transmission 65 (1986), S. 233-243 
    Details
    ISSN: 1435-1463
    Keywords: Gas chromatography ; hydroxylation ; p-hydroxytranylcypromine ; mass spectrometry ; monoamine oxidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The formation ofp-hydroxytranylcypromine from intraperitoneally injected tranylcypromine was confirmed using two types of experiments. In the first, tranylcypromine levels were shown to be increased in brains of rats pretreated with agents known to be inhibitors of ring hydroxylation compared to rats pretreated with physiological saline. For the second set of experiments,p-nydroxytranylcypromine was identified in brain and urine (following intraperitoneal injection) by derivatizing with perfluoroacylating reagents and analyzing by electron-capture gas chromatography and by combined gas chromatography-mass spectrometry. In experimentsin vitro, p-hydroxytranylcypromine was demonstrated to inhibit monoamine oxidase, although it was weaker than TCP in this regard and was a much stronger inhibitor of MAO-A than of MAO-B.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01249085
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  • 5
    Electronic Resource
    Electronic Resource
    Immunocytochemistry of neurotransmitter receptors (1990)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 15 (1990), S. 81-96 
    Details
    ISSN: 0741-0581
    Keywords: Antibody ; GABA ; Glycine ; Acetylcholine ; Auditory system ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Over the last several years our knowledge of neurotransmitter receptors has increased dramatically as receptor types and subtypes have been identified through the development of selective antagonists, neuropharmacological studies, and radioactive ligand binding studies. At the same time major advances were made in the immunocytochemical localization of neurotransmitters and their related enzymes. However, only recently has immunocytochemistry been used to localize neurotransmitter receptors, and these studies have been limited. Four receptors have been localized in the CNS with immunocytochemistry: the nicotinic acetylcholine receptor, the beta-adrenergic receptor, the GABA/benzodiazepine receptor, and the glycine receptor. Of these the glycine receptor has been the most thoroughly characterized. Glycine receptor immunoreactivity is highly concentrated at postsynaptic sites, and the distribution of immunoreactivity appears to correlate closely with glycinergic neurons. However, immunocytochemical studies done on other receptors suggest such a distribution may not always be the case. Some receptors may not be concentrated at postsynaptic sites, and receptor distribution may not always closely fit the distribution of the respective neurotransmitter. Work is rapidly progressing on the purification of other receptors and on the production of selective antibodies which will allow immunocytochemical studies which address these and other questions.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1060150108
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