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  • 1
    Electronic Resource
    Electronic Resource
    Elevated Phosphatidyl-CMP Is Not the Source of Diacylglycerol Accumulation Induced by Lithium in NG108-15 Cells (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 60 (1993), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Previous studies have shown that in the neuroblastoma X glioma hybrid cell line NG108-15 lithium is able to induce an increase in diacylglycerol levels. This effect was shown to be enhanced by the presence of bradykinin. Another striking effect of lithium was a marked gain in the level of the liponucleotide phosphatidyl-CMP. Increased phosphatidyl-CMP levels were detected in the presence of lithium alone but were considerably more pronounced in the presence of both lithium and bradykinin. These results are consistent with the inhibitory action of lithium on key enzymes of the degradation pathway of inositol phosphates, resulting in a decrease in cellular inositol content and in an elevation in levels of phosphorylated inositols. Comparison of the mass of the inositol phosphates and diacylglycerol showed that the lithium-induced diacylglycerol levels were substantially greater than would be expected from phosphoinositide hydrolysis alone. One possible reason for the increase in the level of diacylglycerol through the action of lithium is the reversal of the reaction for the formation of phosphatidyl-CMP. The resulting phosphatidic acid would then need to be further dephosphorylated to diacylglycerol. The lithium-induced elevation of phosphatidyl-CMP was prevented by addition of myo-inositol (10–30 mM), suggesting that the increase in liponucleotide level was due to depletion of cellular inositol. Under the same conditions the elevated diacylglycerol concentration remained unchanged. Consequently, phosphatidyl-CMP is not its source, and diacylglycerol may arise through an effect of lithium on the degradation of phospholipids other than phosphoinositides. The action of phospholipase C or D on phosphatidylcholine is the most likely mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1993.tb03264.x
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  • 2
    Electronic Resource
    Electronic Resource
    Stimulation of Phosphoinositide Hydrolysis by Serotonin in C6 Glioma Cells (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 48 (1987), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: 5-Hydroxytryptamine (serotonin or 5-HT) stimulated the incorporation of 32Pi into phosphatidylinositol (PI) but not into polyphosphoinositides in C6 glioma cells with an EC50 of 1.2 ± 10-7M. The phosphoinositide response was blocked by the 5-HT2 antagonists ketanserin and spiperone but inhibited only partly by methysergide and mianserin. Atropine, prazosin, and yohimbine did not block the response, whereas fluphenazine and haloperidol did so partially but also inhibited basal incorporation by ˜30%. The 5-HT1A agonist 8-hydroxy-2 (di-n-propylamino)tetralin did not cause stimulation. Incubation with 5-HT (1 μM) for 1 h increased the incorporation of [2-3H]myo-inositol into all phosphoinositides but not into inositol phosphates (IPs). Li+ alone at 10 mM increased labeling in inositol bisphosphate (IP2) and trisphosphate (IP3), whereas labeling in IP and phosphoinositides remained unaltered. Addition of 5-HT had no effect on this increase. Mn2+ at 1 mM enhanced labeling in PI, PI-4-phosphate, lyso-PI, glycerophosphoinositol, and IP, but the presence of 5-HT again did not cause further stimulation. 5-HT also stimulated the release of IPs in cells prelabeled with [2-3H]myo-inositol, incubated with LiCl (10 mM) and inositol (10 mM), and then exposed to 5-HT (1 μM). Radioactivity in IP2 and IP3 was very low, was stimulated ˜50% as early as 30 s, and remained elevated for at least 20 min. Radioactivity in IP was at least 10 times as high as in IP3 but was increased only from 3 min on with a peak at 20 min, when the elevation was ˜40 times that in IP3. The EC50 value of 1.8 ± 10-7M was comparable with that obtained from 32Pi studies measuring labeled PI. Ketanserin and spiperone inhibited 5-HT-stimulated [2-3H]IP release with IC50 values of 3.1 ± 10-9 and 1.8 ± 10, -8M, respectively. This study demonstrates that phosphoinositide hydrolysis is enhanced by 5-HT in C6 glioma cells and that this phenomenon is linked to 5-HT2-like binding sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1987.tb13156.x
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  • 3
    Electronic Resource
    Electronic Resource
    Differential Expression and Subcellular Localization of Protein Kinase C α, β, γ, δ, and ɛ Isoforms in SH-SY5Y Neuroblastoma Cells: Modifications During Differentiation (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 60 (1993), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: A decrease in protein kinase C activity caused either by treatment with inhibitors, such as staurosporine or H-7, or by prolonged exposure to phorbol diesters has been proposed to be involved in the early events of SH-SY5Y neuroblastoma cell differentiation. Because eight distinct isoforms of protein kinase C with discrete subcellular and tissue distributions have been described, we determined which isoforms are present in SH-SY5Y cells and studied their modifications during differentiation. The α, β, δ, and ɛ isoforms were present in SH-SY5Y cells, as well as in rat brain. Protein kinase C-α and -β1 were the most abundant isoforms in SH-SY5Y cells, and immunoreactive protein kinase C-δ and -ɛ were present in much smaller amounts than in rat brain. Subcellular fractionation and immunocytochemistry demonstrated that all four isoforms are distributed bimodally in the cytoplasm and the membranes. Immunocytochemical analysis showed that the α isoform is associated predominantly with the plasma membrane and the processes extended during treatment with 12-tetradecanoyl-13-acetyl-β-phorbol or staurosporine, and that protein kinase C-ɛ is predominantly membrane-bound. Its localization did not change during differentiation. Western blots of total SH-SY5Y cell extracts and of subcellular fractions probed with isoform-specific polyclonal antibodies showed that when SH-SY5Y cells acquired a morphologically differentiated phenotype, protein kinase C-α and -ɛ decreased, and protein kinase C-β1, did not change. These data suggest distinct roles for the different protein kinase C isoforms during neuronal differentiation, as well as possible involvement of protein kinase α and ɛ in neuritogenesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1993.tb05850.x
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  • 4
    Electronic Resource
    Electronic Resource
    Distinct Mechanisms of Differentiation of SH-SY5Y Neuroblastoma Cells by Protein Kinase C Activators and Inhibitors (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 58 (1992), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Certain biological actions of phorbol esters cannot be duplicated by diacylglycerol (DAG). Thus, the human neuroblastoma cell line SH-SY5Y differentiates when exposed to 12-tetradecanoyl-13-acetyl-β-phorbol (TPA) and protein kinase C (PKC) inhibitors, but not when exposed to DAG. To investigate the specific features of the phorbol diester molecule that might be responsible for these effects, we examined the extension of neurites, expression of neuron-specific enolase, and appearance and localization of phosphorylated high molecular weight neurofilament subunits (NF-H). TPA, 12-deoxy-13-tetradecanoyl-β-phorbol, and staurosporine, but not DAG or 4-O-methyl-TPA, caused neurite outgrowth. Neuron-specific enolase was expressed in cells treated with TPA and 12-deoxy-13-tetradecanoyl-β-phorbol but not with DAG, staurosporine, or 4-O-methyl-TPA. NF-H increased in the perikarya of cells treated with DAG and 4-O-methyl-TPA, in processes and to varying degrees in perikarya of TPA- and 12-deoxy-13-tetradecanoyl-β-phorbol-treated cells, but much more in the processes than in the perikarya of staurosporine-differentiated cells. These findings and additional differences between the differentiation induced by TPA (a PKC activator) and staurosporine (a PKC inhibitor), including distinct morphology of the cell body and processes and time of appearance of the morphological phenotype, suggest that activators and inhibitors of PKC induce differentiation of SH-SY5Y cells by different mechanisms, and that the five-membered/seven-membered terpene ring region present in TPA must be intact for the induction of morphological differentiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1992.tb11328.x
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  • 5
    Electronic Resource
    Electronic Resource
    Accumulation of Inositol Phosphates Induced by Chlorpromazine in C6 Glioma Cells (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 53 (1989), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Chlorpromazine, a cationic amphiphilic drug known to affect phospholipid metabolism, greatly increases the generation of inositol phosphates in C6 glioma cells. When a pulse-chase protocol with myo-[2-3H]inositol as the radioactive precursor was used, the peak increase in radioactivity of inositol phosphates was observed at 20 min. The drug decreased inositol tetrakisphosphate labeling as a percentage of inositol trisphosphate in a dose-dependent manner. It also increased the labeling of the inositol-containing phospholipids, the precursors of the inositol phosphates. The increase in radioactivity of both phospholipids and inositol phosphates was dose-dependent, but appeared also to be a function of the time of exposure of the cultures to the drug, suggesting that the concentration of chlorpromazine in the cell, and not that in the medium, is the critical factor. The optimum concentration for maximum phospholipid labeling was lower than that eliciting maximum generation of inositol phosphates. The data suggest that the mechanism probably does not involve cell-surface receptors, but rather may consist of a direct effect of chlorpromazine on phosphoinositidase C and possibly other enzymatic reactions concerned with the metabolism of inositol phosphates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1989.tb09262.x
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of Changes in Calcium Concentration on Basal and Stimulated 32P Incorporation into Phospholipids in Rat Pineal Cells (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 37 (1981), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The Ca2+ requirement for α-agonist stimulation of 32P incorporation into acidic phospholipids (the phosphatidylinositol effect) of dispersed pineal cells was evaluated by means of several different compounds that interfere with Ca2+ disposition. Simple omission of Ca2+ led to slight increases in basal and norepinephrine-stimulated phosphatidyl-CMP (CDP-diacylglycerol) and phosphatidylglycerol labeling without affecting phosphatidylinositol labeling. In the absence of Ca2+, EGTA (200 μM) or the ionophore for divalent cations A23187 (10 μM) elicited large increases in phosphatidic acid, phosphatidyl-CMP, and phosphatidylglycerol labeling while strongly inhibiting the phosphatidylinositol effect. The Ca2+ translocation inhibitor LaCI3 also reduced the magnitude of this effect. The phosphatidylinositol effect is, however, not induced by increased Ca2+ entry into the cytosol, since A23187 did not mimic the effect of norepinephrine. Under conditions where membrane Ca2+ was lowered, the addition of 1 mM-inositol greatly reduced phosphatidic acid, phosphatidylglycerol, and phosphatidyl-CMP labeling with concomitant increases in basal and norepinephrine-stimulated phosphatidylinositol labeling approaching that observed in the presence of norepinephrine and 2.5 mM-Ca2+. In the presence of 2.5 mM-Ca2+, inositol had negligible effects on phosphatidylinositol labeling. It was concluded that changes in membrane Ca2+ availability and/or disposition alter phospholipid metabolism and concurrently reduce the magnitude of the phosphatidylinositol effect, perhaps by making the pool of readily available inositol in pinealocytes rate-limiting.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1981.tb00473.x
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  • 7
    Electronic Resource
    Electronic Resource
    Evidence Against Dopaminergic and Further Support For α-Adrenergic Receptor Involvement in the Pineal Pho sphatidy lino sitol Effect (1980)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 34 (1980), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Several α-adrenergic receptor agonists and antagonists were used to strengthen the earlier findings that the stimulation by (-)-norepinephrine of 32P1 incorporation into acidic phospholipids, especially phosphatidylinositol, in the rat pineal gland is mediated through α-adrenergic receptors. Dopamine was able to induce similar stimulation, although always to a smaller extent than equimolar concentrations of norepinephrine. The dopaminergic agonists apomorphine and piribedil did not increase phosphatidylinositol labeling. A number of antagonists considered to act primarily at dopaminergic or α-adrenergic receptors respectively completely prevented dopamine from exerting its effect. Both types of antagonists also were able to inhibit in varying degree the elevation of phospholipid labeling induced by norepinephrine. Dopamine increased phosphatidylinositol turnover without first being converted to norepinephrine, inasmuch as dopamine β-hydroxylase inhibitors had no influence on dopamine activity. Dopamine and α-agonists competitively activated the receptors involved in the phospholipid effect. The conclusion drawn from the several lines of evidence is that only α-adrenergic receptors are concerned with the changes in pineal phospholipid metabolism brought about by the various agonists used and that the action of dopamine occurs through these receptors rather than through discrete dopaminergic receptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1980.tb09652.x
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  • 8
    Electronic Resource
    Electronic Resource
    Alterations of Phospholipid Metabolism in Rat Cerebral Cortex Mince Induced by Cationic Amphiphilic Drugs (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 37 (1981), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract Cationic amphiphilic drugs (CADs) of varied clinical use were screened to determine their capacity to alter the pattern of labeling with 32Pj of cerebral cortex mince phospholipids. The altered phospholipid labeling patterns were qualitatively similar, the prominent features being reduced incorporation into phosphatidylcholine and increased incorporation into phosphatidic acid. Relative potencies were: (±)-propranolol 〉 chlorpromazine = 4,4′-bis(diethylaminoethoxy) α,β-diethyldiphenylethane 〉 desipramine 〉 di-bucaine 〉 pimozide 〉 oxymetazoline = fenfluramine = haloperidol = chloroquine 〉 amphetamine = no drug added. Propranolol was used to study the action of CADs further. Its effect was time- and dose-dependent, but in contrast with pineal gland, no label appeared in phosphatidyl-CMP (CDP-diacylglycerol), nor did dialysis of the mince to reduce diffusible substrates or exogenous addition of substrates cause appearance of liponucleotide. Thus lack of diffusible precursors is not responsible for CAD effects in vitro. Pulse-chase experiments with 32P1 and [2-3H]glycerol suggested that inhibition of phosphatidate phosphohydrolase may be partly responsible for the observed alterations in phospholipid labeling in the presence of CADs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1981.tb04488.x
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  • 9
    Electronic Resource
    Electronic Resource
    INCORPORATION OF GLUCOSE CARBON INTO GANGLIOSIDES AND CEREBROSIDES BY SLICES OF DEVELOPING RAT BRAIN (1967)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 14 (1967), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1967.tb09544.x
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  • 10
    Electronic Resource
    Electronic Resource
    POLYPHOSPHOINOSITIDE BIOSYNTHESIS IN DEVELOPING RAT BRAIN HOMOGENATES (1970)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 165 (1970), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1970.tb56443.x
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