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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Neurochemical research 14 (1989), S. 1195-1201 
    ISSN: 1573-6903
    Keywords: Naftidrofuryl ; neuronal cultures ; survival ; glucose transport lactate production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The direct influence of Naftidrofuryl, a drug widely used for the treatment of cerebrovascular diseases, on the metabolism and survival of neurons was investigated in 8-day-old chick embryo forebrain cultures. Interaction of Naftidrofuryl with neurons resulted in the increase of the intracellular cyclic AMP levels. Naftidrofuryl stimulated deoxyglucose uptake and lactate production in a time- and dose-dependent fashion. These effects were observed after a few minutes following the beginning of the treatment with Naftidrofuryl. In parallel to the action on the metabolic activities, Naftidrofuryl was able to increase the survival rate of a significant proportion of the neuronal population. These data support the notion that Naftidrofuryl may act as a neuroprotective agent.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-6903
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Superoxide dismutase (EC 1.15.1.1) activity was investigated in several types of neural cells cultivated in the presence of 100 mM ethanol. Superoxide dismutase was inhibited by acute treatment with ethanol. Chronic treatment with ethanol specifically inhibited superoxide dismutase in glial cells. In all instances withdrawal of ethanol produced a quick return to control values. Inhibition of superoxide dismutase by ethanol may increase toxic oxygen radicals in nervous tissue.
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  • 3
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The influence of ACTH and some of its N-terminal related peptides was investigated on the uptake of (3H)-2-deoxy-D-glucose in pure cultures of neurons from chick embryo cerebral hemispheres. ACTH influences deoxyglucose uptake in a time and dose-dependent fashion. The stimulation of deoxyglucose uptake is observed after a delay of 6-8 h and requires active protein synthesis. ACTH does not affect deoxyglucose in non-neuronal cells (astroglial cells, hepatocytes, myoblasts, fibroblasts). The effect of various peptide hormones, neuropeptides and growth factors, active in the central nervous system or other tissues, has also been examined. None of these were able to stimulate deoxyglucose uptake, suggesting that the regulation of hexose uptake in neurons is specific for the ACTH-related peptides.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Glial cell line-derived neurotrophic factor (GDNF) is a potent survival factor for midbrain dopaminergic neurons. To begin to understand the intracellular signaling pathways used by GDNF, we investigated the role of phosphatidylinositol 3-kinase activity in GDNF-stimulated cellular function and differentiation of dopaminergic neurons. We found that treatment of dopaminergic neuron cultures with 10 ng/ml GDNF induced maximal levels of Ret phosphorylation and produced a profound increase in phosphatidylinositol 3-kinase activity, as measured by western blot analysis and lipid kinase assays. Treatment with 1 µM 2-(4-morpholinyl)-8-phenylchromone (LY294002) or 100 nM wortmannin, two distinct and potent inhibitors of phosphatidylinositol 3-kinase activity, completely inhibited GDNF-induced phosphatidylinositol 3-kinase activation, but did not affect Ret phosphorylation. Furthermore, we examined specific biological functions of dopaminergic neurons: dopamine uptake activity and morphological differentiation of tyrosine hydroxylase-immunoreactive neurons. GDNF significantly increased dopamine uptake activity and promoted robust morphological differentiation. Treatment with LY294002 completely abolished the GDNF-induced increases of dopamine uptake and morphological differentiation of tyrosine hydroxylase-immunoreactive neurons. Our findings show that GDNF-induced differentiation of dopaminergic neurons requires phosphatidylinositol 3-kinase activation.
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  • 5
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Here we report the generation and characterization of two distinct monoclonal antibodies, G-90 and B-1531, specific to glial cell line-derived neurotrophic factor (GDNF). ELISA results confirmed that G-90 and B-1531 both recognize GDNF. Western blots showed that G-90 recognized only the GDNF dimer, whereas B-1531 recognized both the monomer and dimer. Peptide competition ELISA (PCE) and BIAcore data suggested that G-90 and B-1531 recognize different epitopes: PCE confirmed that B-1531 binds to NH2-terminal peptides between amino acids 18 and 37, whereas G-90 does not; BIAcore data showed that B-1531 binds to the NH2 terminus of GDNF, whereas G-90 does not. G-90, in a concentration-dependent manner, completely neutralized the GDNF-induced increases of choline acetyltransferase in cultured motoneuron and of dopamine uptake and morphological differentiation in dopaminergic neuron cultures. B-1531 had no neutralizing effects. GDNF-induced Ret autophosphorylation in NGR-38 cells was completely neutralized by G-90, whereas B-1531 had a moderate effect. These data show that G-90 and B-1531 are specific antibodies to GDNF. The data also suggest that the NH2 terminus of GDNF is not critical for activity. Partial inhibition of Ret phosphorylation is insufficient to downregulate GDNF-induced biological activity.
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  • 6
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The c-ret protooncogene encodes Ret, the functional tyrosine kinase receptor for glial cell line-derived neurotrophic factor (GDNF). K-252b, a known protein tyrosine kinase inhibitor, has been shown earlier to inhibit the trophic activity of brain-derived neurotrophic factor on dopaminergic (DAergic) neurons and nerve growth factor on basal forebrain cholinergic neurons while potentiating neurotrophin-3 activity on central cholinergic and peripheral sensory neurons and PC12 cells. We tested whether K-252b would modulate GDNF-induced differentiation in DAergic neuron cultures. Exposure to 1 ng/ml GDNF increased dopamine (DA) uptake 80% above control, whereas treatment with 5 µM K-252b decreased the efficacy of GDNF by 60%. Concentrations of GDNF of 〈100 pg/ml were completely inhibited, whereas concentrations of 〉100 pg/ml were moderately active, between 10 and 20% above control. In addition, K-252b shifted the ED50 from 20 to 200 pg/ml. GDNF treatment increased soma size and neurite outgrowth in tyrosine hydroxylase-immunoreactive neurons. K-252b inhibited differentiation of these morphological parameters induced by GDNF. Furthermore, GDNF stimulated Ret autophosphorylation at maximal levels, whereas the inhibition of DA uptake and morphological differentiation by K-252b correlated with a significantly decreased level of Ret autophosphorylation. Therefore, K-252b is able to inhibit intracellular activities induced by GDNF on mesencephalic DAergic neurons.
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  • 7
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Complete obstruction of the maternal blood flow to fetal rats at 20 days of gestation for a period of 10 min causes a significant shift of ∼22% in protein kinase C (PKC) activity from a cytosolic to a membrane-bound form in the fetal brain. This translocation can be entirely reversed without losses in activity by a single intraperitoneal injection into the gravid rat of either a mixture of disialo- and trisialoganglioside [polysialoganglioside (PSG)] or by GM1 (50 mg/kg of body weight) given 3 h before onset of the ischemic episode. Cessation of blood flow for 15 min followed by a reperfusion period of 24 h results in a 47% loss in total PKC activity. This down-regulation can be almost entirely prevented upon intraperitoneal administration of GM1 3 h before, but also during and even 90 min after the onset of ischemia. The PSG mixture is also effective, particularly when given 3 h before the insult. Down-regulation of PKC is accompanied by an increase in a Ca2+-phosphatidylserinc-indepcndent kinase [protein kinase M (PKM)] activity, which rises from 30 pmol/min/mg of protein in control animals to a maximal value of 83.1 pmol/min/mg of protein after 15 min of ischemia and 6 h of reperfusion. By 24 h, PKM activity is 46.8 pmol/min/mg of protein. Administration of GM1 blocks completely the appearance of PKM, a result suggesting that PKC down-regulation and PKM activity elevation are intimately associated events and that both are regulated by GM1 ganglioside.
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  • 8
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Recent evidence suggests that protein kinase C (PKC) is involved in the pathophysiology of neurodegenerative diseases. We examined the effect of basic fibroblast growth factor (bFGF) on the survival of cultured rat hippocampal neurons exposed to conditions in which PKC is likely to play a role. bFGF reduced neuron damage caused by the PKC-activating phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA), glutamate and ischaemia-like culture conditions. bFGF was able to counteract the excessive activation of PKC caused by these treatments. Moreover, bFGF prevented the loss of PKC occurring after prolonged exposure to TPA or ischaemia-like conditions. These results indicate that both the overactivation and the abnormal degradation of PKC can lead to neuron degeneration, and that the neurotrophic competence of bFGF may reside in its ability to regulate and normalize the PKC phosphorylating system.
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