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  • 1
    Digitale Medien
    Digitale Medien
    Changes of Activity and Isozyme Pattern of Phosphofructokinase in the Brains of Patients with Alzheimer's Disease (1996)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 67 (1996), S. 0 
    Details
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract: A severe reduction of the in vivo cerebral glucose consumption rate is generally found in patients with Alzheimer's disease. In postmortem studies changes in the activities of key regulatory glycolytic enzymes, including 6-phosphofructokinase (PFK), have been reported in Alzheimer's disease brains, but the results obtained so far are inconsistent and controversial. We reevaluated the activity of PFK in brain tissue from clinically and neuropathologically confirmed cases of Alzheimer's disease using optimized tissue disintegration and assay methods and determined the PFK isozyme pattern. PFK activity in brains from patients with Alzheimer's disease was significantly increased in frontal and temporal cortex and unchanged in the other brain areas studied when compared with control brains. All three PFK isozymes were detected in each of the brain areas studied. In brains of Alzheimer's disease patients the level of the C-type PFK was slightly reduced at the expense of the M- and L-type subunits. The data presented do not support the results of other groups, which reported up to a 90% reduction of PFK activity in Alzheimer's disease. In contrast, the data presented clearly rule out the suggestion that changes of PFK activity might be one of the causes for the reduced glucose consumption in Alzheimer's disease brains.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1471-4159.1996.67031164.x
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  • 2
    Digitale Medien
    Digitale Medien
    The Effect of Visual Deprivation on β-Adrenergic Receptors in the Visual Centres of the Rat Brain (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 38 (1982), S. 0 
    Details
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract: The levels of binding of [3H]dihydroalprenolol to β-adrenergic receptors in the visual centres and frontal cortex from brains of control, dark-reared and monocularly deprived rats were compared. Receptor binding is changed in monocularly deprived rats in the lateral geniculate nuclei and superior colliculi of both sides. Scatchard analyses indicated that the changes in the [3H]dihydroalprenolol binding in the lateral geniculate nuclei were due to alterations in both receptor affinity and receptor number. No effect of dark-rearing could be detected.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1471-4159.1982.tb05345.x
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  • 3
    Digitale Medien
    Digitale Medien
    Subcellular localization suggests novel functions for prolyl endopeptidase in protein secretion (2005)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 94 (2005), S. 0 
    Details
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: For a long time, prolyl endopeptidase (PEP) was believed to inactivate neuropeptides in the extracellular space. However, reports on the intracellular activity of PEP suggest additional, as yet unidentified, physiological functions for this enzyme. Here, we demonstrate using biochemical methods of subcellular fractionation, immunocytochemical double-labelling procedures and localization of PEP–enhanced green fluorescent protein fusion proteins that PEP is mainly localized to the perinuclear space, and is associated with the microtubulin cytoskeleton in human neuroblastoma and glioma cell lines. Disassembly of the microtubules by nocodazole treatment disrupts both the fibrillar tubulin and PEP labelling. Furthermore, in a two-hybrid screen, PEP was identified as binding partner of tubulin. These findings indicate novel functions for PEP in axonal transport and/or protein secretion. Indeed, a metabolic labelling approach revealed that both PEP inhibition and PEP antisense mRNA expression result in enhanced peptide/protein secretion from human U-343 glioma cells. Because disturbances in intracellular transport and protein secretion mechanisms are associated with a number of ageing-associated neurodegenerative diseases, cell-permeable PEP inhibitors may be useful for the application in a variety of related clinical conditions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1471-4159.2005.03237.x
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  • 4
    Digitale Medien
    Digitale Medien
    Cholinergic Control of Nerve Growth Factor in Adult Rats: Evidence from Cortical Cholinergic Deafferentation and Chronic Drug Treatment (1997)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 69 (1997), S. 0 
    Details
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract: It is well documented that nerve growth factor (NGF) plays an important role in maintaining functions of cholinergic basal forebrain neurons. In the present study, we tested the hypothesis that cholinergic activity controls NGF levels in cholinoceptive neurons of the cerebral cortex and hippocampus. To address that question, we used both cholinergic deafferentation of cerebral cortex and hippocampus by cholinergic immunolesion with 192IgG-saporin and chronic pharmacological treatment of sham-treated and immunolesioned rats with the cholinergic agonist pilocarpine and the cholinergic antagonist scopolamine. We observed an increase in NGF protein levels in the cortex and hippocampus after cholinergic immunolesions and also after muscarinic receptor blockade by chronic intracerebroventricular scopolamine infusion in sham-treated rats after 2 weeks. There was no further increase in the accumulation of NGF after scopolamine treatment of immunolesioned rats. Chronic infusion of pilocarpine had no effect on cortical and hippocampal NGF protein levels in sham-treated rats. In rats with cholinergic immunolesions, however, pilocarpine did prevent the lesion-induced accumulation of NGF. There was no effect of cholinergic lesion and drug treatment on cortical or hippocampal NGF mRNA levels, consistent with the importance of NGF retrograde transport as opposed to its de novo synthesis. This study provides strong evidence for the hypothesis that there is cholinergic control of cortical and hippocampal NGF protein but not mRNA levels in adult rats.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1471-4159.1997.69030947.x
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  • 5
    Digitale Medien
    Digitale Medien
    Constitutive overactivation of protein kinase C in guinea pig brain increases α-secretory APP processing without decreasing β-amyloid generation (2000)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 12 (2000), S. 0 
    Details
    ISSN: 1460-9568
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Whilst it is generally accepted that the activation of protein kinase C (PKC) increases amyloid precursor protein (APP) secretion in vitro, the role of PKC in the regulation of APP processing and β-amyloid generation in vivo is still not well understood. In order to address this question, we established the animal model of neocortical microencephalopathy in guinea pigs caused by in utero treatment with methylazoxymethanol acetate, a DNA-methylating substance that eliminates proliferating cells of neuroepithelial origin. The induction of this neocortical malformation is accompanied by constitutive overactivation of PKC in the neocortex of the offspring. In the cortical and hippocampal tissues of juvenile microencephalic guinea pigs (postnatal day 30), we observed significant increases in basal (by 58% and 74%, respectively,) and phorbol ester-stimulated PKC enzyme activity (by 47% and 71%) as compared to age-matched control animals. In the same cortical/hippocampal preparations of methylazoxymethanol-treated animals, there was increased α-secretion of APP by 35% and 30% as measured by Western blot analysis using the antibody 6E10, whilst total APP secretion as well as APP mRNA expression remained unaltered. This upregulation of APP α-secretion was limited to brain areas that displayed elevated PKC activity. However, constitutive overactivation of neocortical PKC did not affect the generation of β-amyloid peptides 1–40 or 1–42 as measured by ELISA, suggesting that only the α-secretase pathway of APP processing is affected by chronic PKC overactivation in vivo.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1460-9568.2000.00211.x
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  • 6
    Digitale Medien
    Digitale Medien
    In Vivo Regulation of Amyloid Precursor Protein Secretion in Rat Neocortex by Cholinergic Activity (1997)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 9 (1997), S. 0 
    Details
    ISSN: 1460-9568
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: The proteolytic cleavage of the amyloid precursor protein (APP) has been shown to be modulated through specific muscarinic receptor activation in vitro in both transfected cell lines and native brain slices, whereas a demonstration of receptor-mediated control of APP processing under in vivo conditions is still lacking. To simulate alterations in muscarinic receptor stimulation in vivo, we have (i) specifically reduced the cortical cholinergic innervation in rats using partial immunolesions with 192lgG–saporin, and (ii) restored cholinergic function in lesioned rats by transplantation of nerve growth factor producing fibroblasts. While total APP levels in cortical homogenates were unaffected by cholinergic deafferentation, we observed a significant reduction in the abundance of secreted APP and a concomitant increase in membrane-bound APP. These changes were reversed in immunolesioned rats with nerve growth factor-producing fibroblasts. There was a strong positive correlation between the ratio of secreted APP to membrane-bound APP and the activity of choline acetyltransferase and M1 muscarinic acetylcholine receptor density (measured by [3H]pirenzepine binding) in experimental groups. Additionally, we observed a transient decrease in the ratio of cortical APP transcripts containing the Kunitz protease inhibitor domain (APP 770 and APP 751) versus APP 695 in rats with cholinergic hypoactivity. The data presented suggest that cortical APP processing is under basal forebrain cholinergic control, presumably mediated through M1 muscarinic acetylcholine receptors on cholinoceptive cortical target cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1460-9568.1997.tb01379.x
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  • 7
    Digitale Medien
    Digitale Medien
    Effect of Monocular Deprivation on Uptake and Binding of [3H]Glutamate in the Visual System of Rat Brain (1984)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 43 (1984), S. 0 
    Details
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract: [3H]Glutamate uptake and binding studies were performed in the visual cortices, lateral geniculate nuclei (LGN), and superior colliculi of 3-month-old rats with one eyelid surgically closed from postnatal day 10 (monocular deprivation). Uptake and binding were highest in the lateral geniculate nucleus followed by the visual cortex (69% and 15%, respectively compared to LGN values) and the superior colliculus (32% and 59% of LGN values). Monocular deprivation did not affect [3H]glutamate uptake in any of the visual regions examined. However, a 46% decrease in [3H]glutamate binding in the lateral geniculate nucleus ipsilateral to the sutured eye was detected. Binding levels in other regions were not affected.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1471-4159.1984.tb05414.x
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  • 8
    Digitale Medien
    Digitale Medien
    Changes in activity and expression of phosphofructokinase in different rat brain regions after basal forebrain cholinergic lesion (2002)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 83 (2002), S. 0 
    Details
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Selective lesion of rat basal forebrain by the cholinergic immunotoxin 192IgG-saporin was used as an animal model to address the question of whether the changes in cortical glucose metabolism observed in patients with Alzheimer's disease may be related to impaired cholinergic transmission. At different times after creating the immunolesion, the isoenzyme pattern and steady-state mRNA levels of the key glycolytic enzyme phosphofructokinase were determined in cortex, hippocampus, basal forebrain and nucleus caudatus. The loss of cholinergic input was accompanied by a persistent decrease in choline acetytransferase and acetylcholine esterase activities in the cortical target areas similar to the cholinergic malfunction seen in Alzheimer's dementia. The basal forebrain lesion induced by the immunotoxin resulted in a transient increase in phosphofructokinase activity peaking on day 7 after inducing the lesion in cortical areas. In parallel, an increased steady-state level of phosphofructokinase mRNA was determined by RT/real-time PCR and in situ hybridization. In contrast, analysis by western blotting and quantitative PCR revealed no changes in the phosphofructokinase isoenzyme pattern after immunolesion. It is concluded that common metabolic mechanisms may underlie the degenerative and repair processes in denervated rat brain and in the diseased Alzheimer's brain.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1471-4159.2002.01127.x
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  • 9
    Digitale Medien
    Digitale Medien
    Digoxigenylated primary antibodies for sensitive dual-peroxidase labelling of neural markers (1995)
    Springer
    Histochemistry and cell biology 104 (1995), S. 467-472 
    Details
    ISSN: 1432-119X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract This study extends the application of the digoxigenin-anti-digoxigenin (DIG) technique to immunocytochemistry by using digoxigenin-tagged primary antibodies. Certain features of this technique when applied to non-radioactive in situ hybridization, such as the absence of endogeneous digoxigenin immunoreactivity in animal tissues, seem to be advantageous also for its application to immunocytochemistry. Thus, the present work is focused on dual-peroxidase staining experiments based on digoxigenylated antibodies directed against glial fibrillary acidic protein, parvalbumin, and calbindin, in a straightforward combination with conventional cytochemical methods. The protocols include the concomitant detection of two antigens, for which only primary antibodies from one animal species are available, with differently haptenized antibodies (e.g., biotinylated anticalbindin and digoxigenylated anti-parvalbumin). The versatility of the DIG technique is exemplified by the combination of lectin and immunocytochemical procedures for the detection of astrocytes and microglia, and the simultaneous visualization of perineuronal nets and parvalbumin-containing neurons in the rat brain.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01464337
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  • 10
    Digitale Medien
    Digitale Medien
    Potentiating and depressant effects of metabotropic glutamate receptor agonists on high-voltage-activated calcium currents in cultured retinal ganglion neurons from postnatal mice (1994)
    Springer
    Pflügers Archiv 426 (1994), S. 161-170 
    Details
    ISSN: 1432-2013
    Schlagwort(e): Retinal ganglion neurons ; Patch clamp ; Ca2+ channels ; mGluR agonists ; ACPD ; Fura-2 ; Cytosolic Ca2+
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract This study was aimed at clarifying the role of metabotropic glutamate receptors (mGluRs) in the regulation of intracellular Ca2+ concentration ([Ca2+]i) in postnatal mouse retinal ganglion neurons (RGNs). RGNs were maintained for 1–2 weeks in vitro by adding brain-derived neurotrophic factor (BDNF) and basic fibroblast growth factor (bFGF) to the culture medium. In order to select these cells for electrophysiological measurements, RGNs were vitally labelled with an antibody against Thy-1.2. Voltage-activated Ca2+ currents [I Ca(V)] were recorded with patch electrodes in the wholecell configuration. It was found that racemic ±-1-aminocyclopentane-trans-1, 3-dicarboxylic acid (t-ACPD) or its active enantiomer 1S,3R-ACPD rapidly and reversibly either enhanced or depressed I Ca(V). Quisqualate (QA), l-2-amino-4-phosphonobutyrate (l-AP4) and the endogenous transmitter glutamate induced similar effects when ionotropic glutamate receptors were blocked with d-2-amino-5-phosphonovalerate (d-APV) and 6,7-dinitroquinoxaline-2, 3-dione (DNQX). ω- Conotoxin GVIA (ω-CgTx GVIA), but not nifedipine prevented modulation of I Ca(V) by mGluR agonists. The depression of I Ca(V) by t-ACPD was irreversible when cells were dialysed with guanosine-5′-O-(3-thiotriphosphate) (GTP[γ-S]). Ratio measurements of fura-2 fluorescence in Thy-1+ cells showed that neither t-ACPD, QA nor l-AP4 affected [Ca2+]i by liberation of Ca2+ from intracellular stores. Our results suggest that cultured RGNs express mGluRs. These receptors cannot induce Ca2+ release from intracellular stores but regulate [Ca2+]i by a fast and reversible, G-protein-mediated action on a subpopulation of voltage-activated Ca2+ channels.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00374684
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