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  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We have previously demonstrated that dopaminergic neurons in midbrain–striatum slice co-cultures are more resistant to NMDA cytotoxicity than the same neuronal population in single midbrain slice cultures. Here, we show that dopaminergic neurons in midbrain–striatum co-cultures also exhibit resistance to the cytotoxicity of nitric oxide donors, 2,2′-(hydroxynitrosohydrazono)bis-ethanamine (NOC-18) and 3-morpholinosydnonimine (SIN-1). The cytotoxicity of NMDA (30 µm) in single cultures was significantly attenuated by the nitric oxide synthase (NOS) inhibitor Nω-nitro-l-arginine (100 µm), whereas the toxicity in co-cultures was not. The levels of tyrosine residue nitration of tyrosine hydroxylase, a hallmark of the occurence of peroxynitrite anion in dopaminergic neurons, were lower in co-cultures than those in single cultures. Single cultures and co-cultures did not show appreciable differences in the number or distribution of NOS-containing neurons as assessed by NADPH diaphorase histochemistry. On the other hand, midbrain slices cultured with striatal slices showed higher levels of superoxide dismutase (SOD) activity as well as increased protein levels of Cu,Zn-SOD, than midbrain slices cultured alone. These results suggested that the generation of NO is involved in NMDA cytotoxicity on dopaminergic neurons, and that increased activity of SOD in co-cultures renders dopaminergic neurons resistant to NMDA cytotoxicity by preventing the formation of peroxynitrite.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract : Using primary neuronal cultures, we investigated the effects of GSH depletion on the cytotoxic effects of glutamate and NO in dopaminergic neurons. Intracellular GSH was depleted by 24-h exposure to L-buthionine-[S,R]-sulfoximine (BSO), an irreversible inhibitor of GSH synthase. BSO exposure caused concentration-dependent reduction of the viability of both dopaminergic and nondopaminergic neurons. In contrast, 24-h exposure of cultures to glutamate or NOC18, an NO-releasing agent, significantly reduced the viability of non-dopaminergic neurons without affecting that of dopaminergic neurons. Pretreatment with N-acetyl-L-cysteine for 24 h ameliorated the NOC18-induced toxicity in nondopaminergic neurons. In dopaminergic neurons, sublethal concentrations of BSO reduced intracellular GSH content and markedly potentiated glutamate- and NOC-18-induced toxicity. These results suggested that glutamate toxicity was enhanced in dopaminergic neurons by suppression of defense mechanisms against NO toxicity under conditions of GSH depletion. Under such conditions, free iron plays an important role because BSO-enhanced NO toxicity was ameliorated by the iron-chelating agent, deferoxamine. These results suggest that GSH plays an important role in the expression of NO-mediated glutamate cytotoxicity in dopaminergic neurons. Free iron may be related to enhanced NO cytotoxicity under GSH depletion.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: 3-Hydroxykynurenine (3-HK) is a potential endogenous neurotoxin whose increased levels have been described in several neurodegenerative disorders. Here, we characterized in vitro neurotoxicity of 3-HK. Of the tested kynurenine pathway metabolites, only 3-HK, and to a lesser extent 3-hydroxyanthranilic acid, were toxic to primary cultured striatal neurons. 3-HK toxicity was inhibited by various antioxidants, indicating that the generation of reactive oxygen species is essential to the toxicity. 3-HK-induced neuronal cell death showed several features of apoptosis, as determined by the blockade by macromolecule synthesis inhibitors, and by the observation of cell body shrinkage with nuclear chromatin condensation and fragmentation. In addition, 3-HK toxicity was dependent on its cellular uptake via transporters for large neutral amino acids, because uptake inhibition blocked the toxicity. Cortical and striatal neurons were much more vulnerable to 3-HK toxicity than cerebellar neurons, which may be attributable to the differences in transporter activities of these neurons. These results indicate that 3-HK, depending on transporter-mediated cellular uptake and on intracellular generation of oxidative stress, induces neuronal cell death with brain region selectivity and with apoptotic features, which may be relevant to pathology of neurodegenerative disorders.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Glial cell activation associated with inflammatory reaction may contribute to pathogenic processes of neurodegenerative disorders, through production of several cytotoxic molecules. We investigated the consequences of glial activation by interferon-γ (IFN-γ)/lipopolysaccharide (LPS) in rat midbrain slice cultures. Application of IFN-γ followed by LPS caused dopaminergic cell death and accompanying increases in nitrite production and lactate dehydrogenase release. Aminoguanidine, an inhibitor of inducible nitric oxide synthase (iNOS), or SB203580, an inhibitor of p38 mitogen-activated protein kinase, prevented dopaminergic cell loss as well as nitrite production. SB203580 also suppressed expression of iNOS and cyclooxygenase-2 (COX-2) induced by IFN-γ/LPS. A COX inhibitor indomethacin protected dopaminergic neurons from IFN-γ/LPS-induced injury, whereas selective COX-2 inhibitors such as NS-398 and nimesulide did not. Notably, indomethacin was able to attenuate neurotoxicity of a nitric oxide (NO) donor. Neutralizing antibodies against tumour necrosis factor-α and interleukin-1β did not inhibit dopaminergic cell death caused by IFN-γ/LPS, although combined application of these antibodies blocked lactate dehydrogenase release and decrease in the number of non-dopaminergic neurons. These results indicate that iNOS-derived NO plays a crucial role in IFN-γ/LPS-induced dopaminergic cell death, and that indomethacin exerts protective effect by mechanisms probably related to NO neurotoxicity rather than through COX inhibition.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 21 (2005), S. 0 
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Neuroactive steroids can modulate brain excitability by interaction with several neurotransmitter receptor-associated channels. These compounds may thus exert profound influences on excitotoxic injury, i.e. neuronal cell death triggered by over-activation of glutamate receptors. It has been reported that pregnenolone sulphate (PS) and pregnenolone hemisuccinate (PHS) augment N-methyl-d-aspartate (NMDA) neurotoxicity in rat cultured neurons. Here we show that the effects of neuroactive steroids on AMPA cytotoxicity display features distinct from those on NMDA cytotoxicity. Concomitant application of PS (30–300 µm) attenuated, rather than augmented, AMPA neurotoxicity in cortical slice cultures in a concentration-dependent manner, whereas various other steroids including pregnenolone and PHS had no effect. Inhibition of steroid sulphatase by estrone-3-O-sulphamate led to a shift of the minimum effective concentration of PS against AMPA cytotoxicity from 30 to 10 µm. The protective action of PS was not affected by inhibition of protein synthesis or by blockade of glucocorticoid receptors, GABAA receptors or σ-receptors. In dissociated cortical neurons, PS attenuated AMPA-induced inward currents whereas pregnenolone and PHS exhibited no significant effect. Thus, with strict structural specificity, PS but not pregnenolone or PHS attenuates AMPA cytotoxicity, probably by inhibiting activities of AMPA receptor-associated channels.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-6903
    Keywords: Garlic ; thioallyl group ; rat hippocampus ; neuronal survival ; axonal branching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Several organosulfur compounds found in garlic extract promoted the survival of rat hippocampal neurons in vitro. From the analysis of structure-activity relationship, thioallyl group in these compounds is essential for the manifestation of neurotrophic activity. S-Allyl-L-cysteine (SAC), one of the organosulfur compounds having thioallyl group in garlic extract, also promoted the axonal branching of cultured neurons. These results suggest that thioallyl compounds make a unique group of neurotrophic factors.
    Type of Medium: Electronic Resource
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