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  • 1
    Online Resource
    Online Resource
    New York, NY :Springer,
    Keywords: Parkinson's disease-Pathophysiology-Congresses. ; Electronic books.
    Type of Medium: Online Resource
    Pages: 1 online resource (225 pages)
    Edition: 1st ed.
    ISBN: 9781461307594
    DDC: 616.833
    Language: English
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  • 2
    Online Resource
    Online Resource
    Berlin, Heidelberg :Springer Berlin / Heidelberg,
    Keywords: Nerve growth factor. ; Electronic books.
    Type of Medium: Online Resource
    Pages: 1 online resource (259 pages)
    Edition: 1st ed.
    ISBN: 9783642467226
    Series Statement: Research and Perspectives in Alzheimer's Disease Series
    DDC: 612.81
    Language: English
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  • 3
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The present study compares the effects of chronic administration of basic fibroblast growth factor (bFGF) and nerve growth factor (NGF) on various hippocampal cholinergic parameters in rats with partial unilateral fimbrial transections. Lesions resulted in marked reductions of several presynaptic cholinergic parameters: choline acetyltransferase (ChAT) activity (by 50%), [3H]-acetylcholine ([3H]ACh) synthesis (by 59%), basal and ve-ratridine (1 μM)-evoked [3H]ACh release (by 44 and 57%, respectively), and [3H]vesamicol binding site densities (by 35%). In addition, [3H]AF-DX 116/muscarinic M2 binding site densities were also modestly decreased (by 23%). In contrast, [3H]pirenzepine/muscarinic M1 and [3H]AF-DX 384/muscarinic M2/M4 binding site densities were not altered by the lesions, nor were they affected by any of the treatments. Intracerebroventricular administration of bFGF (10 ng, every other day, for 21 days) partially prevented the lesion-induced deficit in hippocampal ChAT activity, an effect that was not markedly different from that measured in the NGF-treated (1 μg intracerebroventricularly, every other day, for 21 days) rats. In rats treated with a combination of bFGF and NGF, ChAT activity was not different from that in rats treated with the individual factors alone. In contrast, the lesion-induced deficits in the other cholinergic parameters were not attenuated by bFGF treatment, although they were at least partially prevented by NGF administration. To determine whether higher concentrations of bFGF are necessary to affect cholinergic parameters other than hippocampal ChAT activity, rats were treated with 1 μg (every other day, 21 days) of the growth factor. In this group of rats, detrimental effects of bFGF, manifested by an increased death rate (46%), and marked reductions in body weight of the survivors, were observed. In addition, this concentration of bFGF appeared to exacerbate the lesion-induced reduction in [3H]ACh synthesis by hippocampal slices; [3H]ACh synthesis in lesioned hippocampi represented 36 and 52% of that in contralateral unlesioned hippocampi for the bFGF-treated and control groups, respectively. In conclusion, although bFGF administration attenuates the deficit in hippocampal ChAT activity induced by partial fimbrial transections, this does not appear to translate into enhanced functional capacity of the cholinergic terminals. This is clearly in contrast to NGF, which enhances not only hippocampal ChAT activity, but also other parameters indicative of increased function in the cholinergic terminals.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: To enable us to study expression of tyrosine hydroxylase [TH; tyrosine 3-monooxygenase; L-tyrosine tetrahydropteridine: oxygen oxidoreductase (3-hydroxylating); EC 1.14.16.2] as a measure of dopaminergic neuron function in future experiments, methods were developed to quantify TH mRNA levels in cultures of dopaminergic mesencephalic cells. The model of selective dopaminergic toxicity of 1-methyl-4-phenylpyridinium (MPP+) was used to verify the specificity of our methods. Fetal (embryonic day 15) rat ventral mesencephalic cell cultures were treated with 15 μMMPP+ for 48 h, conditions previously shown to reduce the number of TH-immunoreactive neurons, TH activity, and dopamine uptake to 5–10% of control values. This treatment decreased the number of neurons labeled by TH in situ hybridization to 9% of untreated controls and caused a strong reduction of the abundance of TH mRNA in Northern blots. Our findings establish TH mRNA expression as a parameter for future studies of toxic and trophic effects on cultured dopaminergic neurons, and they support the view that MPP+ destroys dopaminergic neurons.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Phospholipase Cγ1 (PLC-γ1) is involved at an early step in signal transduction of many hormones and growth factors and catalyzes the hydrolysis of phosphatidylinositol (PI) 4,5-bisphosphate to diacylglycerol and inositol trisphosphate, two potent intracellular second messenger molecules. The transformation of PC12 cells into neuron-like cells induced by nerve growth factor is preceded by a rapid stimulation of PLC-γ1 phosphorylation and PI hydrolysis. The present study analyzed the effects of brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) on phosphorylation of PLC-γ1 in primary cultures of embryonic rat brain cells. BDNF and NT-3 stimulated the phosphorylation of PLC-γ1, followed by hydrolysis of PI. The stimulation of PLC-γ1 phosphorylation occurred within 20 s after addition of BDNF or NT-3 and lasted up to 30 min, with a peak after 4 min. ED50 values were similar for BDNF and NT-3, with τ25 ng/ml. Phosphorylation of PLC-γ1 by BDNF and NT-3 was found in cultures from all major brain areas. K-252b, a compound known to inhibit selectively neurotrophin actions by interfering with the phosphorylation of trk-type neurotrophin receptors, prevented the BDNF- and NT-3-stimulated phosphorylation of PLC-γ1. Receptors of the trk type were coprecipitated with anti-PLC-γ1 antibodies. The presence of trkB mRNA in the cultures was substantiated by northern blot analysis. The action of BDNF and NT-3 seems to be neuron specific because no phosphorylation of PLC-γ1 was observed in cultures of nonneuronal brain cells. The results provide evidence that developing neurons of the cerebral cortex and other brain areas are responsive to BDNF and NT-3, and they indicate that the transduction mechanism of BDNF and NT-3 in the brain involves rapid phosphorylation of PLC-γ1 followed by PI hydrolysis.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Phosphatidylinositol (PI) breakdown represents a powerful system participating in the transduction mechanism of some neurotransmitters and growth factors and producing two second messengers, diacylglycerol and inositol trisphosphate. The transformation of PC12 neuroblastoma cells into neuron-like cells induced by nerve growth factor (NGF) is preceded by a rapid stimulation of PI breakdown; however, it was not known whether PI breakdown mediates actions of other members of the neurotrophin family. The present study analyzed the effects of NGF, brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3) on PI breakdown in primary cultures of embryonic rat brain cells. Cultures were grown for 7 days; PI was then labeled by incubating cultures with myo-[3H]inositol, which then were exposed acutely to growth factors. BDNF and NT-3, but not NGF, elevated the levels of labeled inositol phosphates within 10–15 min after addition to the cultures in a dose-dependent manner. ED50 values for BDNF and NT-3 were 12.4 and 64.5 ng/ml, respectively. Comparable effects were found in cultures of cortical, striatal, and septal cells. The actions of BDNF and NT-3 probably reflect actions on neurons, because no effects were seen in cultures of nonneuronal cells. In contrast, basic fibroblast growth factor induced a marked stimulation of PI breakdown in cultures of nonneuronal cells. K252b, which selectively blocks neurotrophin actions by inhibiting trk-type receptor proteins, prevented the PI breakdown mediated by BDNF and NT-3. The findings suggest that rapid and specific induction of PI breakdown is involved in the signal transduction of BDNF and NT-3, and they provide evidence that cortical neurons are functionally responsive to BDNF and NT-3 during development.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 57 (1991), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: K-252b is a kinase inhibitor structurally related to K-252a, which is known to abolish selectively the effects of nerve growth factor (NGF) on PC12 cells and PNS neurons. We tested whether K-252b, K-252a, and staurosporine, another related compound, are effective and selective inhibitors of NGF actions on CNS neurons. All three compounds, at appropriate concentrations, completely and selectively prevented the NGF-mediated activity increase of the cholinergic marker enzyme choline acetyltransferase in cultures of rat basal forebrain cells. The stimulatory effects of basic fibroblast growth factor and insulin on choline acetyltransferase in these cultures and on dopamine uptake in cultures of dissociated ventral mesencephalon were not affected. No signs of toxicity were observed in cultures treated with K-252b. In contrast, K-252a and staurosporine, at concentrations required to block the NGF actions on cholinergic cells, were cytotoxic and produced cell loss. In addition, K-252a, at higher concentrations and in the absence of growth factors, increased cell numbers. Our study suggests that K-252b is a selective and nontoxic inhibitor of NGF actions in the brain and may become a useful tool to study these actions in vivo.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Dopaminergic neurons in cultures of dissociated cells from fetal rat mesencephalon were exposed to the principal metabolite of the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), 1-methyl-4-phenyl-pyridinium ion (MPP+), and several of its structural analogues. At concentrations between 0.01 and 0.1 μM, MPP+ inhibited catecholamine accumulation as visualized by cytofluorescence. Between 0.1 and 10.0 μM, MPP+ resulted in disappearance of tyrosine hydroxylase immunoreactivity without affecting other cells in the cultures. At concentrations higher than 10 μM, MPP+ was toxic to all cells present in the cultures. The effect of low concentrations of MPP+ on catecholamine cytofluorescence of the dopaminergic neurons was partially reversible. The intermediate concentrations produced irreversible structural changes of tyrosine hydroxylase-positive cells, resulting in complete disappearance of these neurons. The morphological changes were specific to the dopaminergic neurons and were not evident in other cells viewed with phase contrast microscopy. Of the structural analogues tested, the 1-ethyl analogue of MPP+ was effective in selectively destroying dopaminergic neurons in our culture system. The antioxidants l-acetylcarnitine, β-carotene, and α-tocopherol failed to protect against MPP+ neurotoxicity when co-incubated with the toxin.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 59 (1992), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 63 (1994), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The protein kinase inhibitors K-252a and K-252b have been shown earlier to block the actions of nerve growth factor and other neurotrophins and, at lower concentrations, to selectively potentiate neurotrophin-3 actions. In the present study we show that K-252a, but not K-252b, enhances epidermal growth factor (EGF)- and basic fibroblast growth factor (bFGF)-induced neurite outgrowth of PC12 cells at higher concentrations than required for neurotrophin inhibition. In parallel, tyrosine phosphorylation of extracellular signal-regulated kinases (Erks) elicited by EGF or bFGF was also increased in the presence of K-252a, and this signal was prolonged for 6 h. EGF- and bFGF-induced phosphorylation of phospholipase C-γ1 were not changed. The effect of K-252a on Erks was resistant to chronic treatment with phorbol ester, indicating that protein kinase C is not involved in this potentiation. In partial contrast to the actions of K-252a, the neurotrophin-3-potentiating effect of K-252b was accompanied by an increase in tyrosine phosphorylation of the Erks and of phospholipase C-γ1. Finally, although K-252a alone did not induce neurite outgrowth or tyrosine phosphorylation of Erks or phospholipase C-γ1, this compound alone stimulated phosphatidylinositol hydrolysis. Our findings identify activities of K-252a besides the direct interaction with neurotrophin receptors and suggest that a K-252a-sensitive protein kinase or phosphatase might be involved in signal transduction for EGF and bFGF. Our results are further compatible with the hypothesis that sustained activation of Erks may be important in PC12 differentiation.
    Type of Medium: Electronic Resource
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