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  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Previous studies have shown that certain peptides of the secretin-glucagon family stimulate tyrosine hydroxylase activity in sympathetic neurons of the superior cervical ganglion and three of its end organs, i.e., the iris, pineal gland, and submaxillary gland. To determine whether a similar regulation occurs in other sympathetic neurons, the effects of two of these peptides, secretin and vasoactive intestinal peptide, were examined in the right cardiac ventricle of the rat, a tissue innervated primarily by the middle and inferior cervical ganglia. Both peptides stimulated tyrosine hydroxylase activity, measured in situ, in this tissue. In addition, several second messenger systems were investigated as possible mediators of this peptidergic stimulation of tyrosine hydroxylase activity in autonomic end organs. 8-Bromoadenosine 3′,5′-cyclic monophosphate and forskolin elevated tyrosine hydroxylase activity in slices of both the right ventricle and the submaxillary gland. 8-Bromoguanosine 3′,5′-cyclic monophosphate also stimulated tyrosine hydroxylase activity in both tissues, whereas nitroprusside stimulated activity only in the submaxillary slices. Furthermore, the phosphodiesterase inhibitors 3-isobutyl-1-methylxanthine and/or Ro 20–1724 potentiated the stimulation by secretin, as well as the stimulations by forskolin and nitroprusside. Phorbol 12,13-dibutyrate also stimulated tyrosine hydroxylase activity in cardiac and submaxillary slices; however, no potentiation of these effects was seen following addition of either phosphodiesterase inhibitor. These data, taken together with those of previous studies, suggest a role for a cyclic nucleotide, probably adenosine 3′,5′-cyclic monophosphate, in the peptidergic stimulation of tyrosine hydroxylase activity in sympathetic nerve terminals.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The absence of adenosine A2A receptors, or its pharmacological inhibition, has neuroprotective effects. Experimental data suggest that glial A2A receptors participate in neurodegeneration induced by A2A receptor stimulation. In this study we have investigated the effects of A2A receptor stimulation on control and activated glial cells. Mouse cortical mixed glial cultures (75% astrocytes, 25% microglia) were treated with the A2A receptor agonist CGS21680 alone or in combination with lipopolysaccharide (LPS). CGS21680 potentiated lipopolysaccharide-induced NO release and NO synthase-II expression in a time- and concentration-dependent manner. CGS21680 potentiation of lipopolysaccharide-induced NO release was suppressed by the A2A receptor antagonist ZM-241385 and did not occur on mixed glial cultures from A2A receptor-deficient mice. In mixed glial cultures treated with LPS + CGS21680, the NO synthase-II inhibitor 1400W abolished NO production, and NO synthase-II immunoreactivity was observed only in microglia. Binding experiments demonstrated the presence of A2A receptors on microglial but not on astroglial cultures. However, the presence of astrocytes was necessary for CGS21680 potentiating effect. In light of the reported neurotoxicity of microglial NO synthase-II and the neuroprotection of A2A receptor inhibition, these data suggest that attenuation of microglial NO production could contribute to the neuroprotection afforded by A2A receptor antagonists.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: This study describes the expression, purification, and characterization of a recombinant fusion toxin, DAB389TTC, composed of the catalytic and membrane translocation domains of diphtheria toxin (DAB389) linked to the receptor binding fragment of tetanus toxin (C-fragment). As determined by its ability to inhibit cellular protein synthesis in primary neuron cultures, DAB389TTC was ∼ 1,000-fold more cytotoxic than native diphtheria toxin or the previously described fusion toxin, DAB389MSH. The cytotoxic effect of DAB389TTC on cultured cells was specific toward neuronal-type cells and was blocked by coincubation of the chimeric toxin with tetanus antitoxin. The toxicity of DAB389TTC, like that of diphtheria toxin, was dependent on passage through an acidic compartment and ADP-ribosyltransferase activity of the DAB389 catalytic fragment. These results suggest that a catalytically inactive form of DAB389TTC may be useful as a nonviral vehicle to deliver exogenous proteins to the cytosolic compartment of neurons.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The cytokines leukemia inhibitory factor (LIF) and ciliary neurotrophic factor (CNTF) have been implicated in determination of neuronal phenotype as well as promotion of neuronal survival. However, the intracellular mechanisms by which their signals are transduced remain poorly understood. We have previously studied the regulation of vasoactive intestinal polypeptide gene expression by LIF and CNTF in the NBFL neuroblastoma cell line. Because these cytokines induce tyrosine phosphorylation that may lead to Ras activation, we explored a possible role for Ras in LIF- and CNTF-induced signal transduction. In NBFL cells LIF increases activated Ras in a rapid, transient, and concentration-dependent manner. CNTF and a related cytokine, oncostatin M, produce similar increases. CNTF and LIF also increase activated Ras in neuron-enriched dissociated cultures of sympathetic ganglia. Moreover, these cytokines rapidly and transiently induce specific tyrosine-phosphorylated proteins, p165 and p195. The protein kinase inhibitors K252a and staurosporine block LIF-induced increases in tyrosine phosphorylation, activated Ras, and vasoactive intestinal polypeptide mRNA in NBFL cells. These data support a possible role for Ras in the cell differentiation effects of LIF and CNTF.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Adenosine A2A receptor (A2AR) antagonism attenuates 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced dopaminergic neurodegeneration and quinolinic acid-induced excitotoxicity in the neostriatum. As A2ARs are enriched in striatum, we investigated the effect of genetic and pharmacological A2A inactivation on striatal damage produced by the mitochondrial complex II inhibitor 3-nitropriopionic acid (3-NP). 3-NP was administered to A2AR knockout (KO) and wild-type (WT) littermate mice over 5 days. Bilateral striatal lesions were analyzed from serial brain tissue sections. Whereas all of the 3-NP-treated WT mice (C57BL/6 genetic background) had bilateral striatal lesions, only one of eight of the 3-NP-treated A2AR KO mice had detectable striatal lesions. Similar attenuation of 3-NP-induced striatal damage was observed in A2AR KO mice in a 129-Steel background. In addition, the effect of pharmacological antagonism on 3-NP-induced striatal neurotoxicity was tested by pre-treatment of C57Bl/6 mice with the A2AR antagonist 8-(3-chlorostyryl) caffeine (CSC). Although bilateral striatal lesions were observed in all mice treated either with 3-NP alone or 3-NP plus vehicle, there were no demonstrable striatal lesions in mice treated with CSC (5 mg/kg) plus 3-NP and in five of six mice treated with CSC (20 mg/kg) plus 3-NP. We conclude that both genetic and pharmacological inactivation of the A2AR attenuates striatal neurotoxicity produced by 3-NP. Since the clinical and neuropathological features of 3-NP-induced striatal damage resemble those observed in Huntington's disease, the results suggest that A2AR antagonism may be a potential therapeutic strategy in Huntington's disease patients.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Stress-activated protein kinase (SAPK) and extracellular signal-regulated kinase (ERK), both members of the mitogen-activated protein kinase (MAPK) family, may in some circumstances serve opposing functions with respect to cell survival. However, SAPK and ERK can also be coordinately activated in neurons in response to glutamate stimulation of NMDA receptors. To explore the mechanisms of these MAPK activations, we compared the ionic mechanisms mediating SAPK and ERK activations by glutamate. In primary cultures of striatal neurons, glutamatergic activation of ERK and one of its transcription factor targets, CREB, showed a calcium dependence typical of NMDA receptor-mediated responses. In contrast, extracellular calcium was not required for glutamatergic, NMDA receptor-mediated activation of SAPK and phosphorylation of its substrate, c-Jun. Increasing extracellular calcium enhanced ERK activation but reversed SAPK activation, further distinguishing the calcium dependencies of these two NMDA receptor-mediated effects. Finally, reducing extracellular sodium prevented the glutamatergic activation of SAPK but only partially blocked that of ERK. These contrasting ionic dependencies suggest a mechanism by which NMDA receptor activation may, under distinct conditions, differentially regulate neuronal MAPKs and their divergent functions.
    Type of Medium: Electronic Resource
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  • 7
    Keywords: Caffeine / Health aspects ; Parkinson's disease / Epidemiology ; Parkinson's disease / Treatment ; Purines ; Caffeine / therapeutic use ; Central Nervous System Stimulants / therapeutic use ; Parkinson Disease / epidemiology ; Parkinson Disease / therapy ; Purines / metabolism ; Uric Acid / therapeutic use
    Description / Table of Contents: Contents: Purines in Parkinson's: from epidemiology of caffeine and urate to therapeutics -- Purines as PD protectants -- Purines & Parkinson’s -- Pursuing Epi clues to protection for Parkinson’s -- Coffee, tea and the risk of PD -- Caffeine consumption and a reduced risk of PD: Possible explanations for this inverse association – Caffeine, post-menopausal estrogen and risk of Parkinson’s disease -- Caffeine targets in humans -- CSC reverses MPTP neurotoxicity -- Adenosine A2A receptor KO mimics caffeine’s protective effect in the MPTP model of PD -- Potential benefits of A2AR blockade in PD -- Caffeine and A2A receptors in models of PD -- Brain distribution of adenosine receptors -- Brain distribution of adenosine receptors -- Industry A2A antagonists advancing to clinical trials for PD -- Caffeine consumption & the risk of dyskinesia in PD -- Urate oxidase mutations during primate evolution -- Advantage of higher urate? -- Epidemiology of urate and PD -- Serum urate predicts progression of Parkinson’s disease -- higher urate predicts a slower rate of PD progression -- Functional imaging can identify dopaminergic deficits of PD -- Higher serum urate at baseline predicts a slower rate of losing DA transporter binding sites in PD -- CSF and serum urate as predictors of progression of Parkinson’s disease -- Is urate a predictor of slower progression in other neurodegenerative diseases? -- Urate prevents dopaminergic neuron death in primary cultures of midbrain neurons -- Astrocytes potentiate the neuroprotective effects of inosine and urate -- Urate prevents MPP+-induced dopaminergic neuron degeneration -- SURE-PD study -- UpUrS-PD study
    Notes: Animated audio-visual presentation with synchronized narration.
    Pages: 1 online resource (1 streaming video file (62 min.) : color, sound).
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