Characterization of 14C-acetate uptake in cultured rat astrocytes

Gliomas are complex and heterogeneous tumors that originate from the glial cells of the brain. The malignant cells undergo deep modifications of their metabolism, and acquire the capacity to invade the brain parenchyma and to induce epigenetic modifications in the other brain cell types. In spite of the efforts made to define the pathology at the molecular level, and to set novel approaches to reach the infiltrating cells, gliomas are still fatal. In order to gain a better knowledge of the cellular events that accompany astrocyte transformation, we developed three increasingly transformed astrocyte cell lines, starting from primary rat cortical astrocytes, and analyzed them at the cytogenetic and epigenetic level. In parallel, we also studied the expression of the differentiation-related H1.0 linker histone variant to evaluate its possible modification in relation with transformation. We found that the most modified astrocytes (A-FC6) have epigenetic and chromosomal alterations typical of cancer, and that the other two clones (A-GS1 and A-VV5) have intermediate properties. Surprisingly, the differentiation-specific somatic histone H1.0 steadily increases from the normal astrocytes to the most transformed ones. As a whole, our results suggest that these three cell lines, together with the starting primary cells, constitute a potential model for studying glioma development.

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Characterization of an Intracellular Alkaline Shift in Rat Astrocytes Triggered by Metabotropic Glutamate Receptors

Journal of Neurophysiology ◽

10.1152/jn.1998.79.2.695 ◽

1998 ◽

Vol 79 (2) ◽

pp. 695-703 ◽

Cited By ~ 14

Author(s):

Brian J. Amos ◽

Mitchell Chesler

Keyword(s):

Sodium Bicarbonate ◽

Glutamate Receptors ◽

Metabotropic Glutamate Receptors ◽

Disulfonic Acid ◽

Metabotropic Glutamate ◽

Alkaline Shift ◽

Atpase Inhibitors ◽

Rat Astrocytes ◽

Ethanesulfonic Acid

Amos, Brian J. and Mitchell Chesler. Characterization of an intracellular alkaline shift in rat astrocytes triggered by metabotropic glutamate receptors. J. Neurophysiol. 79: 695–703, 1998. The modulation of intracellular pH by activation of metabotropic glutamate receptors was investigated in cultured and acutely dissociated rat astrocytes. One minute superfusion of 100 μM (1S,3R)-1-aminocyclopentane-1,3-dicarboxcylic acid (ACPD) evoked an alkaline shift of 0.13 ± 0.013 (mean ± SE) and 0.16 ± 0.03 pH units in cultured (cortical or cerebellar) and acutely dissociated cortical astrocytes, respectively. Alkalinizations were elicited by concentrations of ACPD as low as 1 μM. The ACPD response was mimicked by S-3-hydroxyphenylglycine (3-HPG) and by (s)-4-carboxy-3-hydroxyphenylglycine (4C-3HPG) but was not blocked by α-methyl-4-carboxyphenylglycine (MCPG) or (RS)-1-aminoindan-1,5-dicarboxcylic acid (AIDA), features consistent with an mGluR5 receptor–mediated mechanism. The ACPD-evoked alkaline shift was insensitive to amiloride, 4,4′-diisothiocyanostilbene-2,2′-disulfonic acid (DIDS), and the v-type ATPase inhibitors 7-chloro-4-nitrobenz-2-oxa-1,3-diazol (NBD-Cl), bafilomycin, and concanamycin. The alkaline response persisted in Na+- or Cl−-free saline, but was reversibly blocked in bicarbonate-free, N-2-hydroxyethylpiperazine- N′-2-ethanesulfonic acid (HEPES)-buffered solutions. A bicarbonate-dependent and Na+-independent alkaline shift could also be elicited by either 3 mM caffeine or 1 μM ionomycin. These data suggest that a rise in cytosolic Ca2+ activity is instrumental in triggering the alkalinizing mechanism and that this response is independent of the classic depolarization-induced alkalinization mediated by electrogenic sodium-bicarbonate cotransport.

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