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  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Increasing evidence suggests that enhanced production of reactive oxygen species (ROS) activates the MAP kinases, c-Jun N-terminal protein kinase (JNK) and mitogen-activated protein kinase MAPK (p38). These phosphorylated intermediates at the stress-activated pathway induce expression of matrix metalloproteinases (MMPs), leading to inflammatory responses and pathological damages involved in the etiology of multiple sclerosis (MS). Here we report that N-acetylcysteine amide (AD4) crosses the blood–brain barrier (BBB), chelates Cu2+, which catalyzes free radical formation, and prevents ROS-induced activation of JNK, p38 and MMP-9. In the myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE), a mouse model of MS, oral administration of AD4 drastically reduced the clinical signs, inflammation, MMP-9 activity, and protected axons from demylination damages. In agreement with the in vitro studies, we propose that ROS scavenging by AD4 in MOG-treated animals prevented MMP's induction and subsequent damages through inhibition of MAPK pathway. The low toxicity of AD4 coupled with BBB penetration makes this compound an excellent potential candidate for the therapy of MS and other neurodegenerative disorders.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The etiology of Parkinson's disease is still unknown, though current investigations support the notion of the pivotal involvement of oxidative stress in the process of neurodegeneration in the substantia nigra (SN). In the present study, we investigated the molecular mechanisms underlying cellular response to a challenge by dopamine, one of the local oxidative stressors in the SN. Based on studies showing that nuclear factor kappa B (NF-κB) is activated by oxidative stress, we studied the involvement of NF-κB in the toxicity of PC12 cells following dopamine exposure. We found that dopamine (0.1–0.5 m m) treatment increased the phosphorylation of the IκB protein, the inhibitory subunit of NF-κB in the cytoplasm. Immunoblot analysis demonstrated the presence of NF-κB-p65 protein in the nuclear fraction and its disappearance from the cytoplasmic fraction after 2 h of dopamine exposure. Dopamine-induced NF-κB activation was also evidenced by electromobility shift assay using radioactive labeled NF-κB consensus DNA sequence. Cell-permeable NF-κB inhibitor SN-50 rescued the cells from dopamine-induced apoptosis and showed the importance of NF-κB activation to the induction of apoptosis. Furthermore, flow cytometry assay demonstrated a higher level of translocated NF-κB-p65 in the apoptotic nuclei than in the unaffected nuclei. In conclusion, our findings suggest that NF-κB activation is essential to dopamine-induced apoptosis in PC12 cells and it may be involved in nigral neurodegeneration in patients with Parkinson's disease.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Bcl-2 is an antiapoptotic protein located in the outer mitochondrial membrane. Cellular perturbations associated with programmed cell death may be the consequence of disrupted mitochondrial function as well as excessive production of reactive oxygen species (ROS). Numerous studies indicate that Bcl-2 is involved in opposing cell death induced by oxidative stimuli, but its mode of action is uncertain. We reexamined the role of Bcl-2 by using a loss-of-function model, Bcl-2 knockout mice. Brains from Bcl-2-deficient mice had a 43% higher content of oxidized proteins and 27% lower number of cells in the cerebellum relative to wild-type mice. Incubation of cerebellar neurons from Bcl-2 +/+ brains with 0.5 mM dopamine caused 25% cell death, whereas in Bcl-2-deficient cells, it resulted in 52% death; glial cells provided protection in both cultures. Splenocytes from Bcl-2-deficient mice were also killed more effectively by dopamine as well as paraquat. Bcl-2-deficient mice did not survive intraperitoneal injection of MPTP, which caused a decrease in dopamine level in the striatum of Bcl-2 +/− brains, which was more significant than in wild-type mice. When compared with Bcl-2 +/+ brains, brains of 8-day-old Bcl-2-deficient mice had higher activities of the antioxidant enzymes GSH reductase (192%) and GSH transferase (142%), whereas at the age of 30 days, GSH peroxidase was significantly lower (66%). Activities of GSH transferase and GSH reductase increased significantly (158 and 262%, respectively) from day 8 to day 30 in Bcl-2 +/+ mice, whereas GSH peroxidase decreased (31%) significantly in Bcl-2−/− animals. In summary, our results demonstrated enhanced oxidative stress and susceptibility to oxidants as well as altered levels of antioxidant enzymes in brains of Bcl-2-deficient mice. It is concluded that Bcl-2 affects cellular levels of ROS, which may be due to an effect either on their production or on antioxidant pathways.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: It is believed that oxidative stress (OS) plays an important role in the loss of dopaminergic nigrostriatal neurons in Parkinson's disease (PD) and that treatment with antioxidants might be neuroprotective. However, most currently available antioxidants cannot readily penetrate the blood brain barrier after systemic administration. We now report that AD4, the novel low molecular weight thiol antioxidant and the N-acytel cysteine (NAC) related compound, is capable of penetrating the brain and protects neurons in general and especially dopaminergic cells against various OS-generating neurotoxins in tissue cultures. Moreover, we found that treatment with AD4 markedly decreased the damage of dopaminergic neurons in three experimental models of PD. AD4 suppressed amphetamine-induced rotational behaviour in rats with unilateral 6-OHDA-induced nigral lesion. It attenuated the reduction in striatal dopamine levels in mice treated with 1-methyl-4-phenyl-1,2,3,6,-tetrahydropyridine (MPTP). It also reduced the dopaminergic neuronal loss following chronic intrajugular administration of rotenone in rats. Our findings suggest that AD4 is a novel potential new neuroprotective drug that might be effective at slowing down nigral neuronal degeneration and illness progression in patients with PD.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular neurobiology 17 (1997), S. 101-118 
    ISSN: 1573-6830
    Keywords: monoamines ; neuronal cell death ; apoptosis ; Parkinson's disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 1. The monoamines dopamine (DA), norepinephrine (NE), epinephrine (E), and serotonin (5-HT) serve as endogenous neurotransmitters in the nervous system. We recently reported that the neurotransmitter DA can trigger apoptosis (programmed cell death; PCD) in cultured, postmitotic chick embryo sympatheticneurons, suggesting a role for apoptosis in degenerative processes such as Parkinson's disease (PD). However, PD is also associated with involvement of other monoaminergic (MA) neuronal systems (noradrenergic and serotoninergic), though to a lesser extent. 2. We therefore tested the apoptosis-triggering potential of NE, E, and 5-HT in comparison to the DA effect, in cultured postmitotic nerve growth factor (NGF)-dependent chick embryo sympathetic neurons and mouse cerebellar granule cells. 3. In both model systems MA induced neuronal attrition characteristic of apoptosis. MA caused marked morphological alterations: severe neuronal soma shrinkage, membrane blebbing, nuclear condensation and fragmentation, and axonal disintegration. Flow-cytometric analysis of propidium iodide-stained cell nuclei revealed characteristic apoptotic nuclear fragmentation. MA-induced apoptosis could be blocked by SH-group containing antioxidants but not by inhibitors of transcription and translation. 4. Comparison between the two model systems revealed that the cerebellar granule neurons were distinctly more sensitive to the neurotoxic potential of the MA than sympathetic neuronal cells. Significant differences in the dose dependencies and time course of the apoptotic effect were observed among the examined MA, graded as DA〉NE≈E〉5-HT. 5. We conclude that the apoptosis triggering potential, probably mediated by oxidative metabolites, is shared by all MA tested, but with differential time course and dose dependencies. A correlation can be drawn between the effects of DA vs NE vs 5-HT and the relative involvement of dopaminergic/noradrenergic/serotoninergic pathways in PD, which may suggest a common multisystem underlying abnormality in neuronal apoptosis-control mechanisms.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-6830
    Keywords: Parkinson's disease ; catecholamines ; oxidative metabolites ; phosphorylation ; DNA damage ; apoptosis ; p53
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 1. The pathogenesis of the selective degeneration of the dopaminergic neurons in Parkinson's disease is still enigmatic. Recently we have shown that dopamine can induce apoptosis in postmitotic neuronal cells, as well as in other cellular systems, thus suggesting a role for this endogenous neurotransmitter and associated oxidative stress in the neuronal death process. 2. Dopamine has been shown to be capable of inducing DNA damage through its oxidative metabolites. p53 is a transcription factor that has a major role in determining cell fate in response to DNA damage. We therefore examined the possible correlation between dopamine-triggered apoptosis, DNA damage and levels of total phosphorylated p53 protein in cultured mouse cerebellar granule neurons. 3. Marked DNA damage and apoptotic nuclear condensation and fragmentation were detected within several hours of exposure to dopamine. An associated marked threefold increase in p53 phosphorylation was observed within this time window. Using a temperature-sensitive p53 activation system in leukemia LTR6 cells, were found that p53 inactivation dramatically attenuated dopamine toxicity. 4. We therefore conclude that DNA damage and p53 activation may have a role in mediating dopamine-induced apoptosis. Modulation of the p53 system may therefore have a protective role against the toxicity of this endogenous neurotransmitter and associated oxidative stress.
    Type of Medium: Electronic Resource
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