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  • 1
    Electronic Resource
    Electronic Resource
    Effect of EGF on DNA Labeling in Rat Cerebellar Immature Astrocytes Maintained Under Different Culture Conditions (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 633 (1991), 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.1749-6632.1991.tb15653.x
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  • 2
    Electronic Resource
    Electronic Resource
    Excitatory Amino Acids Stimulate Inositol Phospholipid Hydrolysis and Reduce Proliferation in Cultured Astrocytes (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 54 (1990), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Excitatory amino acids stimulated inositol phospholipid hydrolysis in primary cultures of astrocytes, as reflected by an increased formation of [3H]inositol monophosphate ([3H]InsP) in the presence of 10 mM Li+. Quisqualate was the most potent activator of inositol phospholipid hydrolysis, followed by glutamate and ibotenate. Kainate exhibited low activity, whereas N-methyl-D-aspartate (NMDA) and α-amino-3-hydroxy-5-methylisoxazolepropionate (AMPA) were inactive. The increase in [3H]InsP formation induced by glutamate was potentiated after 12-h exposure to the proliferative agent epidermal growth factor (EGF), suggesting that activation of the mitotic cycle leads to an enhanced coupling of glutamate recognition sites with phospholipase C. To study how glutamate receptors are involved in regulating cell proliferation, we have measured [methyl-3H]thymidine incorporation in cultured astrocytes. Excitatory amino acids reduced thymidine incorporation with a pharmacological profile similar to that observed for the stimulation of inositol phospholipid hydrolysis. Quisqualate acted as a potent antiproliferative agent, both under basal conditions and in cells stimulated to proliferate by addition of EGF or phorbol 12-tetradecanoate 13-acetate. Glutamate and ibotenate reduced [methyl-3H]-thymidine incorporation at high concentrations, whereas kainate, AMPA, and NMDA were virtually inactive. The action of quisqualate on both inositol phospholipid hydrolysis and thymidine incorporation was attenuated by 2-amino-4-phosphonobutyrate, which acted as a weak agonist/competitive antagonist. Other excitatory amino acid receptor antagonists were not effective. Inhibition of [methyl-3H]thymidine incorporation by quisqualate required a lag time of about 4 h and, in cells synchronized to proliferate, occurred when the drug was added during the transition between G0 and G1, but not during the S phase of the mitotic cycle. This suggests that an inducible factor may be involved in the antiproliferative effect of excitatory amino acids. Accordingly, activation of quisqualate receptors led to a rapid and transient increase in mRNA levels of the early inducible gene, c-fos. These results suggest that activation of a specific class of “quisqualate-preferring”excitatory amino acid receptors reduces proliferation of astrocytes in primary cultures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1990.tb02317.x
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  • 3
    Electronic Resource
    Electronic Resource
    Acetylation and Phosphorylation of Histones and Nonhistone Chromosomal Proteins in Neuronal and Glial Nuclei Purified from Cerebral Hemispheres of Developing Rat Brain (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 46 (1986), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The processes of acetylation and phosphorylation of histones and nonhistone proteins (NHPs) in neuronal and glial nuclei purified from cerebral hemispheres of rats at 1, 10, and 30 days of age were investigated. Purified neuronal and glial nuclei were incubated in the presence of [3H]acetyl-CoA and of [γ-32P]ATP. Histones and NHPs were extracted and fractionated by gel electrophoresis. Densitometric and radioactive patterns were obtained. The results showed an increase of acetylation and phosphorylation from 1 to 10 and 30 days of age in both neuronal and glial nuclei in almost all histone and NHP fractions. Among the histones, the H3 fraction was always more labeled than the other fractions and showed the most remarkable differences during postnatal development. In the NHP fractions, the increase in acetylation from 1 to 10 and 30 days of age was more evident in the low-molecular-weight region of neuronal nuclei than in the corresponding fraction of glial nuclei. The appearance of highly phosphorylated proteins (70,000–90,000 daltons)—absent at 1 day, appearing at 10 days, and more evident at 30 days of age—was observed in both neuronal and glial nuclei.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1986.tb08508.x
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  • 4
    Electronic Resource
    Electronic Resource
    Methylation of Chromosomal Proteins in Neuronal and Glial Nuclei Purified from Cerebral Hemispheres of Rat During Postnatal Development (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 44 (1985), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The process of methylation of chromosomal proteins [histones and nonhistone proteins (NHP)] in neuronal and glial cell nuclei obtained from cerebral hemispheres of rats at 1, 10, and 30 days of age was investigated. Purified neuronal and glial nuclei were incubated in the presence of S-adensyl[methyl-3H]methi-onine. Histone and NHPs were extracted and fractionated by polyacrylamide gel electrophoresis. The results obtained indicate remarkable differences in the process of methylation of histones and NHPs between neuronal and glial nuclei, especially during the first period of postnatal development. In both nuclear populations the histone fraction H3 was labeled to a greater degree than the other fractions and showed the major changes during postnatal development. The densitometric and radioactive patterns of NHPs show considerable changes in the two nuclear populations at the various ages examined. The main difference between neuronal and glial nuclei consists in the intense methylation of proteins with a molecular weight of approximately 100,000, which are present in neuronal nuclei and virtually absent in glial ones. The results obtained may be correlated with the different chromatin structures of neuronal and glial nuclei and with the patterns of maturation and differentiation of neuronal and glial cells during postnatal development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1985.tb07168.x
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  • 5
    Electronic Resource
    Electronic Resource
    Transglutaminase increases during astrocyte differentiation by interplay of growth factors and steroids (2003)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 85 (2003), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Development of primary cultured astrocytes can be influenced by interplay of steroids and growth factors (GFs). These mytogenic polypetides regulated the expression of cytoskeletal proteins depending on pretreatment with either dexamethasone (DEX) or estradiol (E2). We evaluated the contribution of each of these treatments to the expression of tissue transglutaminase (tTG), that is involved in cell differentiation. Treatment for 12 h with E2 and EGF as well as DEX and IGF-I significantly increased tTG expression in 15 DIV astrocyte cultures. A proliferative marker, such as cyclinD1 decreased as consequence of treatment increasing tTG expression. Taken together, these results indicate that steroid-GFs cross-talk plays a crucial role during astroglial cell maturation, and tTG may be indicated as mediator of the proliferative/differentiative response of primary cultured astrocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.85.s2.22_7.x
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  • 6
    Electronic Resource
    Electronic Resource
    Basic Fibroblast Growth Factor Priming Increases the Responsiveness of Immortalized Hypothalamic Luteinizing Hormone Releasing Hormone Neurones to Neurotrophic Factors (2000)
    Oxford, UK : Blackwell Science Ltd
    Journal of neuroendocrinology 12 (2000), S. 0 
    Details
    ISSN: 1365-2826
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The participation of growth factors (GFs) in the regulation of luteinizing hormone releasing hormone (LHRH) neuronal function has recently been proposed, but little is known about the role played by GFs during early LHRH neurone differentiation. In the present study, we have used combined biochemical and morphological approaches to study the ability of a number of GFs normally expressed during brain development, including basic fibroblast growth factor (bFGF), epidermal growth factor (EGF), insulin and insulin-like growth factor I (IGF-I) to induce survival, differentiation, proliferation, and phenotypic expression of immortalized (GT1-1) LHRH neurones in vitro, at early (3-days in vitro, 3-DIV) and late (8-DIV) stages of neuronal differentiation. Comparison of GF-treated vs untreated neurones grown in serum-deprived (SD) medium demonstrated bFGF to be the most potent, and insulin the least active in promoting neuronal differentiation. Thus, at both 3-DIV and 8-DIV, but especially at 8-DIV, bFGF induced the greatest increase in the total length and number of LHRH processes/cell and in growth cone surface area. bFGF was also the most active at 3-DIV, and IGF-I at 8-DIV, in counteracting SD-induced cell death, whereas EGF was the most potent in increasing [3H]thymidine incorporation. All GFs studied decreased the spontaneous release of LHRH from GT1-1 cells when applied at 3-DIV or 8-DIV, except for insulin which was inactive at both time-points and bFGF which was inactive at 8-DIV. Pre-treatment of GT1-1 cells with a suboptimal (‘priming’) dose of bFGF for 12 h followed by application of the different GFs induced a sharp potentiation of the neurotrophic and proliferative effects of the latter and particularly of those of IGF-I. Moreover, bFGF priming counteracted EGF-induced decrease in LHRH release and significantly stimulated LHRH secretion following IGF-I or insulin application, suggesting that bFGF may sensitize LHRH neurones to differentiating effects of specific GFs during development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2826.2000.00554.x
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  • 7
    Electronic Resource
    Electronic Resource
    Effect of Growth Factors on Macromolecular Synthesis in Primary Rat Astroglial Cell Cultures (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 692 (1993), 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.1749-6632.1993.tb26217.x
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  • 8
    Electronic Resource
    Electronic Resource
    Age-dependent changes of nucleic acid labeling in different rat brain regions (1989)
    Springer
    Neurochemical research 14 (1989), S. 701-706 
    Details
    ISSN: 1573-6903
    Keywords: Aging ; DNA ; ribosomal RNA ; poly(A)+ RNA ; CDP-choline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of aging on in vivo DNA and RNA labeling and on RNA content in various brain regions of 4-, 12-, and 24-month-old rats were investigated. No difference in [methyl-14C]thymidine incorporation into DNA of cerebral cortex and cerebelllum during aging was observed. The ratio of RNA/DNA content significantly decreased from 4 to 24 months of age in cerebral cortex, cerebellum and striatum. RNA labeling decreased by 15% in cerebral cortex of 24-month-old animals while in the other brain areas examined (cerebellum, hippocampus, hypothalamus, brainstem, striatum) did not change during aging. In the cerebral cortex, the ratio of the specific radioactivity of microsomal RNA to that of nuclear RNA, determined by in vivo experiments, was not affected by the aging process. A significant decrease of total, poly(A)+ RNA and poly(A)- RNA content was observed in the same brain area of 24-month-old rats compared to 4-month-old ones. Moreover, densitometric and radioactivity patterns obtained by gel electrophoresis of labeled RNA after in vitro experiments (tissue slices of cerebral cortex) showed a different ribosomal RNA processing during aging. In vivo chronic treatment with CDP-choline was able to increase RNA labeling in corpus striatum of 24-month-old animals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00964882
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of hypothyroidism on the labeling of the various RNA species in developing rat brain (1985)
    Springer
    Neurochemical research 10 (1985), S. 33-47 
    Details
    ISSN: 1573-6903
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of hypothyroidism on the in vitro incorporation of [3H]uridine into different RNA species in tissue slices of rat cerebral hemispheres at 5, 10, 15, and 21 days of age has been investigated. Gel electrophoresis analysis of total, nuclear and microsomal RNA was also accomplished. The results obtained indicate that RNA labeling is differently influenced by hypothyroidism at the various ages examined. RNA labeling is not significantly affected at 5 days of age while at later ages and especially at 21 days it is higher in hypothyroid rats compared to the controls. Moreover distinct differences at the various ages in the transport of newly synthesized RNA from the nucleus to the cytoplasm in the two groups of animals were found. These results are in agreement with the hypothesis that thyroid hormone deficiency causes a delay of the processes of cell proliferation and differentiation in developing rat brain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00964770
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  • 10
    Electronic Resource
    Electronic Resource
    DNA polymerase and thymidine kinase activities in different regions of rat brain during postnatal development: Effect of undernutrition (1982)
    Springer
    Neurochemical research 7 (1982), S. 943-951 
    Details
    ISSN: 1573-6903
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of undernutrition on the activity of two key enzymes for DNA synthesis, namely DNA polymerase and thymidine kinase, in developing rat brain has been investigated. Both enzymatic activities in cerebral hemispheres and in brain stem are lower in undernourished animals than in controls at the 5th day after birth; succesively, from 5 to 30 days, they decrease in both groups of animals, however the decrease is less drastic in undernourished rats than in controls. At 30 days of age the specific activity of both enzymes is quite similar in the two groups of animals. In the cerebellum, DNA polymerase and thymidine kinase activities increase after 5 days of age showing a peak at around 9 days in controls and at about 13 days in undernourished animals, decreasing thereafter in both groups, although less drastically in undernourished animals, and reaching quite similar values at 30 days. The results obtained show that both enzymatic activities are impaired at 5 days and delayed thereafter, in agreement with the changes of DNA synthesis previously observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00965134
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