guanylyl-imidodiphosphate and Brain-Neoplasms

guanylyl-imidodiphosphate has been researched along with Brain-Neoplasms* in 3 studies

Other Studies

3 other study(ies) available for guanylyl-imidodiphosphate and Brain-Neoplasms

ArticleYear
Characterization of metabotropic glutamate receptors in rat C6 glioma cells.
    European journal of pharmacology, 1997, May-12, Volume: 326, Issue:1

    Metabotropic glutamate receptors in rat C6 glioma cells have been characterized by pharmacological and kinetic binding experiments, using both L-[3H]glutamate and [3H(+/-)-1-aminocyclopentane-trans-1,3-dicarboxylic acid ([3H](+/-)-trans-ACPD) radioligands. Saturation experiments revealed a single binding site with a Kd = 1250 +/- 101 nM and Bmax = 12.1 +/- 1.8 pmol/mg protein when the assays were performed with L-[3H]glutamate as radioligand in the presence of AMPA, kainate, NMDA and DL-threo-beta-hydroxyaspartic acid. When [3H](+/-)-trans-ACPD was used as radioligand, the kinetic parameters obtained were Kd = 2605 +/- 1042 nM and Bmax = 13.66 +/- 5.01 pmol/mg protein. Pharmacological characterization indicated that specific binding of L-[3H]glutamate was sensitive to different agonists of mGlu receptors, showing a rank order of affinity L-glutamate > L-quisqualic acid > (+/-)-1-aminocyclopentane-trans-1,3-dicarboxylic acid (trans-ACPD) > ibotenic acid >>> (2S, 'S,2'S)-2-(carboxycyclopropyl)glycine (L-CCG-I). Specific binding of L-[3H]glutamate to mGlu receptors is regulated by guanine nucleotides. Guanylyl imidodiphosphate (Gpp(NH)p) causes an affinity shift on the L-glutamate dose-response curve, increasing the IC50 value. These results support the evidence that metabotropic glutamate receptors are present in rat C6 glioma cells and they are coupled to a G-protein.

    Topics: Animals; Brain Neoplasms; Cell Membrane; Cycloleucine; Excitatory Amino Acid Agonists; Excitatory Amino Acid Antagonists; Glioma; Glutamic Acid; Guanylyl Imidodiphosphate; Kinetics; Neuroprotective Agents; Radioligand Assay; Rats; Receptors, Metabotropic Glutamate; Tumor Cells, Cultured

1997
G protein modulation of omega-conotoxin binding sites in neuroblastoma x glioma NG 108-15 hybrid cells.
    Journal of neurochemistry, 1992, Volume: 59, Issue:2

    Electrophysiological evidence shows that voltage-dependent calcium channel (VDCC) activity can be regulated by a large number of neurotransmitters. In particular, guanine nucleotide binding regulatory protein (G protein)-mediated inhibitory modulation of the channel activity has been deduced from evidence that GTP analogues and purified G proteins are able to mimic this effect. The G proteins involved are pertussis toxin (PTx) sensitive. The purpose of the present study was to investigate, using biochemical techniques, whether G protein activation modulates the recognition site for omega-conotoxin GVIA (CgTx), a peptide neurotoxin that selectively labels a population of high-threshold VDCC. Undifferentiated and differentiated (1 mM dibutyryl cyclic AMP, 4 days) NG 108-15 cells were used. In both crude cellular extracts specific binding of 125I-CgTx was characterized. Differentiation induced a sixfold increase in the number of binding sites and doubled the KD value. The in vitro addition of guanylylimidodiphosphate (GMP-PNP; a nonhydrolyzable analogue of GTP) to extracts prepared from differentiated cells reduced the 125I-CgTx binding by 48%. This effect, observed in undifferentiated cells as well, was also caused by other triphosphate guanine nucleotides, such as GTP, but not by guanosine 5'-O-(2-thiodiphosphate) or adenine nucleotides. Treatment of the cells with PTx prevented the GMP-PNP effect. Moreover, the results obtained after preincubation with specific antisera raised against the alpha subunits of Gi1-2 and Go suggest that Go is the G protein responsible for the observed effect.

    Topics: Animals; Binding Sites; Brain Neoplasms; Calcium Channels; Glioma; GTP-Binding Proteins; Guanylyl Imidodiphosphate; Hybrid Cells; Immunoblotting; Iodine Radioisotopes; Neuroblastoma; omega-Conotoxin GVIA; Peptides, Cyclic; Pertussis Toxin; Precipitin Tests; Protein Binding; Receptors, Neurotransmitter; Tumor Cells, Cultured; Virulence Factors, Bordetella

1992
The beta-adrenoceptor-coupled adenylate cyclase system in rat C6 glioma cells. Deamplification by isoproterenol and oxaprotiline.
    Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology, 1992, Volume: 7, Issue:2

    The beta-adrenoceptor-coupled adenylate cyclase system in rat C6 glioma cells displays many characteristics observed in brain tissue: using nonlinear regression analysis of agonist competition binding curves, we demonstrated that the bulk of beta-adrenoceptors show high nanomolar affinity for isoproterenol; like in brain tissue, Gpp(NH)p does not shift agonist competition binding curves to the right; and the agonist isoproterenol rapidly downregulates the number of beta-adrenoceptors and deamplifies the norepinephrine signal. However, unlike in brain tissue, where (-)-oxaprotiline fails to decrease the number of beta-adrenoceptors and to desensitize the cyclic adenosine monophosphate generating system, it desensitizes the beta-adrenoceptor-coupled adenylate cyclase system in C6 glioma cells. Determination of the relative steady-state levels of beta-adrenoceptor messenger ribonucleic acid (mRNA) by Northern blot analysis showed a twofold increase in the steady-state levels of the mRNA at 30 minutes following exposure to (-)-isoproterenol or (-)-oxaprotiline. At 48 hours, basal values of mRNA were observed at a time when beta-adrenoceptors were maximally decreased. Further experiments on transcriptional activation, and mRNA stability and translation will be required to unravel the complexity of agonist-dependent and agonist-independent regulation of beta-adrenoceptor density and function.

    Topics: Adenylyl Cyclases; Animals; Antidepressive Agents; Autoradiography; Blotting, Northern; Brain Neoplasms; Cells, Cultured; DNA Probes; Glioma; Guanylyl Imidodiphosphate; Isoproterenol; Maprotiline; Rats; Receptors, Adrenergic, beta; Regression Analysis; RNA; Tumor Cells, Cultured

1992
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