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  • 1
    Electronic Resource
    Electronic Resource
    ADP-Ribosylation of Highly Purified Rat Brain Mitochondria (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 51 (1988), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Highly purified synaptic and nonsynaptic mitochondria were prepared from rat brain, and their ADP-ribosyl transferase and NAD glycohydrolase activities were investigated. Data show that there is no significant difference in ADP-ribosyl transferase activity between these two types of subcellular preparations. However, NAD glycohydrolase activity appeared to be much higher in nonsynaptic mitochondria. The specific activity of both enzymes was investigated in the presence of the inhibitor nicotinamide or its analogue 3-aminobenzamide or other adenine nucleotides, such as ATP or ADP-ribose. The inhibitory effect of nicotinamide or 3-aminobenzamide on ADP-ribosyl transferase appears rather weak compared with their effect on NAD glycohydrolase activity. However, ADP-ribose and ATP appeared more effective in inhibiting ADP-ribosyl transferase. Our results provide evidence for the existence of ADP-ribosyl transferase activity in rat brain mitochondria. When NAD glycohydrolase was inhibited totally by nicotinamide, the transfer of ADP-ribose from NAD to mitochondrial proteins still occurred. The chain length determinations show that the linkage of ADP-ribose to mitochondrial proteins is oligomeric.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1988.tb04854.x
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of Repeated Convulsive Seizures on Brain γ-Aminobutyric Acid Metabolism in Three Sublines of Mice Differing by Their Response to Acoustic Stimulations (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 49 (1987), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The turnover rates and steady-state levels of γ-aminobutyric acid (GABA) have been determined in 15 brain areas of three sublines of inbred mice differing in their susceptibility to audiogenic seizures: Rb3, which is seizure resistant; Rb2, which develops clonic seizures; and Rbl, which develops tonic-clonic seizures. In the Rbl subline, GABA steady-state levels are lower than in the Rb3 subline in three of the 15 areas examined (cerebellum, anterior colliculus, and amygdala), whereas in the Rb2 subline, steady-state levels are either higher (posterior colliculus and hippocampus) or lower (amygdala) than in the Rb3 subline. GABA turnover rates differ in three brain areas in Rbl (amygdala, raphe, and hypothalamus) and in a single area (amygdala) in Rb2 when compared with Rb3. Only one area has similar variations of GABA turnover rate and steady-state levels in the two susceptible sublines: the amygdala. After 2 weeks of repeated auditory stimulations (two times a day, 8,000 Hz, 100 dB), additional alterations in GABA metabolism are observed: mainly large increases in GABA turnover rates (from 40% to three-to fourfold). The Rb2 subline displays a greater number of alterations (increases of turnover rates in pons, cerebellum, anterior and posterior colliculus, amygdala, olfactory bulbs and tubercles, striaturn, and frontal cortex) than the Rb1 subline (increases of turnover rates in cerebellum, posterior colliculus, olfactory tubercles, raphe, and frontal cortex and a decrease in hypothalamus). In the Rb3 subline, increases of the turnover rate in amygdala and olfactory tubercles and decreases in olfactory bulbs and hippocampus are observed. After repeated auditory stimulations, some significant changes of the GABAergic system are specific and common to the seizure-susceptible sublines: an increase of turnover rate in the cerebellum, posterior colliculus, and frontal cortex and a decrease of steady-state level in the hippocampus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1987.tb03418.x
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  • 3
    Electronic Resource
    Electronic Resource
    Brain γ-Aminobutyric Acid Turnover Rates After Spontaneous Chronic Ethanol Intake and Withdrawal in Discrete Brain Areas of C57 Mice (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 47 (1986), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The effect of 4 weeks of spontaneous chronic ethanol intake in drinking water and then ethanol withdrawal on the γ-aminobutyric acid (GABA) steady-state levels and turnover rates was investigated in 15 brain areas of C57 B1/6J alcohol-preferring mice. These mice did not display typical ethanol withdrawal convulsions. There was no statistically significant difference in the brain GABA steady-state levels among the control group, chronic ethanol-treated mice, and mice after ethanol withdrawal. In contrast, chronic ethanol treatment induced significant variations in GABA turnover rate, as measured by gabaculine-induced accumulation of GABA, in eight of 15 areas examined versus a decrease in seven brain areas [cerebellum (–29%), amygdala (–28%), olfactory tubercles (–24%), septum (–24%), striatum (–53%), frontal cortex (–21%), and hippocampus (–24%)]; an increase in turnover rate in the posterior colliculus (100%) was observed. At 26 h after ethanol withdrawal, in the seven areas in which GABA turnover rate decreased after spontaneous chronic ethanol intake, a return to the initial control value was observed; in the posterior colliculus, the turnover rate did not change, remaining higher than the control value. This persisting alteration of GABA turnover rate may be related to the absence of the ethanol withdrawal syndrome in the C57 mouse strain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1986.tb13112.x
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  • 4
    Electronic Resource
    Electronic Resource
    Age-Dependent Changes in Brain GABA Turnover Rates in Two Inbred Strains of Mice (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 45 (1985), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: γ-Aminobutyric acid (GABA) steady-state levels and turnover rates have been determined in 15 brain areas of 21-day- and 3-month-old DBA/2J (DBA) and C57B1/6J (C57) mice. These two inbred strains differ by their susceptiblity to audiogenic seizures; moreover, the involvement of GABAergic neurotransmission has been suggested in the control of this behavior. Turnover rates are generally higher at 21 days than at 3 months of age. There are few significant differences in the GABA steady-state levels between 21-day-old seizure-prone DBA mice when compared with seizure-resistant C57 mice. In the DBA mice, the steady-state level is higher in the olfactory bulbs and lower in the posterior colliculus and the olfactory tubercles than in the C57 mice. Although there are some significant differences in GABA turnover rates and steady-state levels, intra or inter strains, it is difficult to correlate directly these differences with seizure susceptibility.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1985.tb05500.x
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  • 5
    Electronic Resource
    Electronic Resource
    Cytoplasmic poly(ADP-ribose) polymerase and poly(ADP-ribose) glycohydrolase in AEV-transformed chicken erythroblasts (1988)
    Springer
    Molecular biology reports 13 (1988), S. 35-44 
    Details
    ISSN: 1573-4978
    Keywords: poly(ADP-ribose) polymerase ; poly(ADP-ribose) glycohydrolase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Poly(ADP-ribose) polymerase and poly(ADP-ribose) glycohydrolase activities were both investigated in chicken erythroblasts transformed by Avian Erythroblastosis Virus. Respectively 21% and 58% of these activities were found to be present in the post-mitochondrial supernatant (PMS). Fractionation of the PMS on sucrose gradients and poly(A+) mRNA detection by hybridization to [3H] poly(U) show that cytoplasmic poly(ADP-ribose) polymerase is exclusively localized in free mRNP. The glycohydrolase activity sedimented mostly in the 6 S region but 1/3 of the activity was in the free mRNP zone. Seven poly(ADP-ribose) protein acceptors were identified in the PMS in the Mr 21000–120000 range. The Mr 120000 protein corresponds to automodified poly(ADP-ribose) polymerase. A Mr 21000 protein acceptor is abundant in PMS and a Mr 34000 is exclusively associated with ribosomes and ribosomal subunits. The existence of both poly(ADP-ribose) polymerase and glycohydrolase activities in free mRNP argues in favour of a role of poly(ADP-ribosylation) in mRNP metabolism. A possible involvement of this post translational modification in the mechanisms of repression-derepression of mRNA is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00805637
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  • 6
    Electronic Resource
    Electronic Resource
    Ethanolamine base exchange in astrocyte primary cultures: Localization and developmental studies (1987)
    Springer
    Neurochemical research 12 (1987), S. 385-391 
    Details
    ISSN: 1573-6903
    Keywords: Astrocytes ; primary culture ; differentiation ; ethanolamine base exchange enzyme
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The enzymatic activities of ethanolamine base exchange (EBEE) and CDP-ethanolamine: 1,2-diacylglycerol ethanolamine phosphotransferase (EPT) were investigated during the growth of rat astrocyte primary cultures. From the 16th day, cells ceased to divide (2.0×106 cells per culture dish); the total phospholipid (PL) content increased 1.5 fold between the 16th and 24th day (0.20 to 0.30 μmol per mg protein) but the amount of ethanolamine phospholipid (28% of PL content) remained constant. Whereas the specific activity (pmol/ min × mg protein) of EPT reached a plateau at 16 days in culture and remained constant (400) thereafter, that of EBEE increased up to the 19th day (190) and decreased gradually to a basal level (75) at the 24th day. EBEE activity was not detected in plasma membranes isolated from 16, 19 and 24 days astrocyte cultures. Sub-cellular fractionation and determination of EBEE specific activities showed that (1) the 104×103 g fraction (P4) was 4.8 and 8.8 fold enriched at the 16th day and 24th day respectively as compared to the whole cell homogenate (50 and 75). (2) the 7×103 g (P2) and 17×103 g (P3) fractions were 8.4 and 7.0 fold enriched respectively at the 19 day in culture. The percentages of the enzymatic activity in the different subcellular fractions were 30, 57.2 and 25.7 for P2 and 39.2, 2.6 and 39.8 for P4 at 16, 19 and 24 days in culture respectively. The activity remained constant in P3 (23%) and was negligible in P1 (6%). Ultrastructual studies revealed that P2 and P3 were enriched in mitochondria while P4 contained essentially microsomes. P4 was enriched in glucose-6-phosphatase activity (G-6-P microsomal marker) and P2 and P3, in monoaminooxidase (MAO) and succinate dehydrogenase (SDH) (mitochondrial markers); G-6-P, MAO and SDH in the different subcellular fractions remained constant from the 16th to the 24th day. These data indicate (1) that the rate and profile of EPT and EBEE activities differed during the differentiation of astrocyte culture; (2) that EBEE activity, except at the 19th day in culture, was mainly localized in a microsomal subcellular fraction; (3) that at the 19th day the optimal EBEE activity observed in whole cell homogenate correlates with an enrichment of this activity in an enriched mitochondrial subcellular fraction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00993249
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  • 7
    Electronic Resource
    Electronic Resource
    Chick brain glutamine synthetase and Mn2+−Mg2+ interactions (1987)
    Springer
    Neurochemical research 12 (1987), S. 1041-1047 
    Details
    ISSN: 1573-6903
    Keywords: Chick brain ; glutamine synthetase ; enzyme purification ; physico-chemical characteristics ; cation effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Glutamine synthetase (GS) from the chick brain was purified to apparent homogeneity by ammonium sulfate fractionation followed by affinity chromatography, electrofocusing and Sephadex G-150 chromatography. The purified enzyme showed a single band on sodium dodecyl sulfate analysis in polyacrylamide gel. By sedimentation equilibrium analysis and gel electrophoresis analysis, it was shown that the enzyme has a subunit molecular weight of 45,000 and a native molecular weight of 364,000, which is consistent with an octameric structure. Sedimentation analysis in the presence of Mg2+ revealed three different forms of macromolecules corresponding respectively to a monomer, a tetramer and an octamer. Among eight cations tested (Ca2+, Co2+, Fe2+, Li+, Mg2+, Mn2+, Ni2+, Zn2+) only Co2+, Mg2+ and Mn2+ supported GS activity; the order of activatory ability was Mg2+〉Co2+〉Mn2+. The maximum activating effect of Mn2+ occurs only within a very narrow range of concentration: with an excess of cation causing strong inhibition of GS activity. For each cation, maximal GS activity occurs at a defined cation/ATP ratio. A regulatory system in which Mn2+, modulates the Mg2+ dependent GS activity, is proposed; such cation interactions may be of significance in the intracellular control of glutamine synthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00970934
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  • 8
    Electronic Resource
    Electronic Resource
    Glutamine synthetase and energy metabolism enzymes in cultured chick glial cells: Modulation by dibutyryl cyclic AMP, hydrocortisone, and trypsinization (1985)
    Springer
    Neurochemical research 10 (1985), S. 191-200 
    Details
    ISSN: 1573-6903
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Modifications induced by dibutyryl cyclic AMP (diBcAMP) and hydrocortisone in the energy metabolism of chick astroblasts in culture have been investigated. DiBcAMP does not modify the levels of enolase, malate dehydrogenase (MDH), total lactate dehydrogenase (LDH) and glutamine synthetase (GS) activities in these cultured glial cells. However, these cells can be sensitized to the nucleotide analog by trypsinization before seeding. The phenomenon affects specifically GS activity and the synthesis, with an inhibitory effect, of the H subunit of LDH. Addition of hydrocortisone to the culture medium stimulates MDH and GS activities of the cells; trypsinization accentuates the stimulatory effect on GS. This hormone also modifies the synthesis of H and M subunits of LDH in a positive and negative way respectively. The phenomenon is increased by trypsin treatment. The present studies indicate clearly that hydrocortisone generates in cultured chick glial cells metabolic modifications qualitatively different from those obtained by diBcAMP. It is suggested that trypsin treatment, by altering some protein constituents of the cell surface, modifies the adhesiveness of different cell types present in the cell suspension after dissociation of the brain and thus leads to select, in culture, a specific astroglial subpopulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00964567
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  • 9
    Electronic Resource
    Electronic Resource
    Concentrations of physiologically important metal ions in glial cells cultured from chick cerebral cortex (1988)
    Springer
    Neurochemical research 13 (1988), S. 45-50 
    Details
    ISSN: 1573-6903
    Keywords: Manganese ; magnesium ; metal ions ; glial cells ; glutamine synthetase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Energy dispersive x-ray fluorescence and atomic absorption spectroscopy were used to determine the concentrations of Mg, Ca, Mn, Fe, Zn, and Cu in primary cultures of astroglial cells from chick embryo cortex in chemically defined serum-free growth medium. The intracellular volume of cultured glia was determined to be 8.34 μl/mg protein. Intracellular Mn, Fe, Zn, and Cu in these cells were ca. 10–200 μM, or 20–200 times the concentrations in the growth medium. Mg2+ was 7 mM in glial cells, only four-fold higher than in growth medium. Glutamine synthetase (GS), compartmentalized in glia, catalyzes a key step in the metabolism of neurotransmitterl-glutamate as part of the glutamate/glutamine cycle between neurons and glia. Hormones (insulin, hydrocortisone, and cAMP) added to growth medium differentially altered the activity of GS and the intracellular level of Mn(II), but not Mg(II). These findings suggest the possibility that glutamine synthetase activity could be regulated in brain by the intracellular levels of Mn(II) or the ratio of Mn(II)/Mg(II), which may in turn be controlled indirectly by means of transport processes that respond to hormones or secondary metabolic signals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00971853
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  • 10
    Electronic Resource
    Electronic Resource
    γ-Hydroxybutyrate uptake by rat brain striatal slices (1985)
    Springer
    Neurochemical research 10 (1985), S. 387-396 
    Details
    ISSN: 1573-6903
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract γ-Hydroxybutyrate uptake by rat brain striatal slices was studied. The uptake was saturable with aK m of 702±107.10−6M. γ-Hydroxybutyrate uptake was sodium dependent and inhibited by the omission of potassium. In addition, the effect of ouabain suggests that the transport is dependent on a cation gradient. Several analogues of γ-hydroxybutyrate inhibit the transport system. GABA has no significant effect. This energy and cation dependent transport system is in favor of a transmitter or modulator role of γ-hydroxybutyrate in the rat brain striatum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00964607
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