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Query: UMLS:C0017638 (glioma)
 30,880 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The C6 glioma cell line contains nerve growth factor (NGF) which can be released into the medium. Treatment of the cells with beta-adrenoceptor agonists resulted in increased content of NGF in both the cells and the medium within a few hours, whereas alpha-adrenoceptor agonists were ineffective. The response was blocked by beta- but not alpha-adrenoceptor antagonists. The increase of the NGF content of glioma cells appeared to be mediated by an elevation of cyclic AMP or GMP. The addition to the cell cultures of other putative neurotransmitters failed to change the content of either NGF or cyclic AMP. These results are discussed with respect to a model for adrenergic neuron-glial interactions.
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PMID:Regulation of nerve growth factor content in C6 glioma cells by beta-adrenergic receptor stimulation. 2 24

Two novel beta-adrenergic myocardial stimulants of general structure: Formula: (see text), where R is a phenyl or benzyl group were investigated for their ability to stimulate and desensitize the cyclic AMP response of C6 glioma cells. Compound ICI 89, 963 (R:phenyl) which elicited less than 1% of the maximum increase in cAMP produced by isoproterenol, was strikingly effective as a desensitizer of the isoproterenol response. This desensitization was markedly reduced by propranolol. Compound ICI 119,033 (R: benzyl) which was a more effective stimulant of cAMP synthesis than ICI 89,963, was also a more effective desensitizer of the isoproterenol response of C6 cells. The kinetics of the desensitization by ICI 89,963 were comparable with those for isoproterenol reaching a maximum in 2 to 3 hours. The data indicate that beta-adrenergic agonists are more potent as desensitizers of the cyclic AMP response than as stimulants of that response.
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PMID:Desensitization of beta receptor mediated cyclic AMP response of cultured fibroblasts by partial agonists. 3 55

The aminobenzyl analog of propranolol, 1- (p-amino-alpha,alpha-dimethylphenethylamino)-3-(1-naphthoxy)-2- propanol, was synthesized and found to be a potent beta-adrenergic blocking agent. The beta-adrenergic receptors of cultured rat C6 glioma cells (2B clone) as assessed by [(125)I]iodohydroxybenzylpindolol binding were decreased 50 and >95% after pretreatment with 8 nM and 1 muM aminobenzylpropranolol, respectively. Unlike propranolol, aminobenzylpropranolol displayed a prolonged blockade of receptors that was maintained during several hours of washing. [(125)I]Iodohydroxybenzylpindolol saturation binding experiments in cells exposed to aminobenzylpropranolol and subsequently washed indicated that the compound effectively diminished receptor number with no change in the affinity of the remaining receptors for iodohydroxybenzylpindolol. Aminobenzylpropranolol inhibited catecholamine-stimulated intracellular cyclic AMP accumulation; with increasing blockade, isoproterenol dose-response curves became progressively shifted to the right but the maximal response was unaltered. Aminobenzylpropranolol inhibited the beta-adrenergic contractile response in atria isolated from rats and guinea pigs. Treatment with 0.1 and 10 muM aminobenzylpropranolol produced decreases of 0.5 and 2 orders of magnitude in the contractile potency of isoproterenol. As in glioma cells, aminobenzylpropranolol failed to decrease the maximal response to isoproterenol. The effects of aminobenzylpropranolol persisted during extensive washing of atria (up to 17 hr). Repeated exposures to isoproterenol at concentrations sufficient to produce maximal tension development also failed to alleviate the blockade. The inotropic potency of histamine in guinea pig atria was not affected by aminobenzylpropranolol. These data suggest that catecholamines are capable of eliciting full biological responses in glioma cells and isolated atria even though the great majority of beta-adrenergic receptors are persistently blocked.
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PMID:Quantitative relationship between beta-adrenergic receptor number and physiologic responses as studied with a long-lasting beta-adrenergic antagonist. 4 15

Nutrient transport rates and cyclic AMP levels have been implicated in the regulation of cell proliferation. In the present study, however, changes in intracellular cyclic AMP level in several lines of cultured cells (normal 3T3 and SV40 and polyomavirus-transformed 3T3 cells; 3T6, C6 GLIOMA, MOUSE L, and Novikoff rat hepatoma cells) by treatment with papaverine, prostaglandine E1 or isoproterenol did not correlate with the inhibition of the uridine, hypoxanthine or deoxyglucose transport rates by these chemicals. Transport inhibitions by above chemicals or Persantin or Cytochalasin B occurred in most cell lines in the absence of any measurable change in intracellular cyclic AMP concentration. Furthermore, treatment of several cell lines with 1 mM dibutyryl cyclic AMP had no immediate effect on the transport of uridine, thymidine or deoxyglucose, although the transport capacity of the cells for uridine and thymidine, but not that for deoxyglucose, decreased progressively with time of treatment. We also observed that the uridine transport system of all cell lines derived from 3T3 cells and the hypoxanthine transport system of L cells exhibited high degrees of resistance to inhibition by the various chemicals. On the other hand, deoxyglucose transport was inhibited to about the same extent by these chemicals in all the cell lines investigated.
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PMID:Cyclic AMP, membrane transport and cell division. I. Effects of various chemicals on cyclic AMP levels and rate of transport of neucleosides, hypoxanthine and deoxyglucose in several lines of cultured cells. 16 72

Rat glioma cells grown in culture secrete cyclic adenosine 3':5'-monophosphate (cyclic AMP) into the culture medium following stimulation by beta-agonistic catecholamines. Agents which reduced cellular ATP levels such as valinomycin, oligomycin, and uncouplers of oxidative phosphorylation, inhibited cyclic AMP efflux. Secretion of cyclic AMP was also prevented by prostaglandin A-1 and pharmacological agents including probenecid and papaverine. Of the latter agents, only papaverine reduced ATP levels. These results suggest that the transport of cyclic AMP across animal cell membranes is energy-dependent and subject to regulation.
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PMID:Regulation of adenosine 3' :5'-monophosphate efflux from rat glioma cells in culture*. 16

Six biochemically differentiated clonal lines have been established from a transplantable glioma (tg26) of the C57BL/6 inbred mouse strain. Antibodies have been previously raised against G26 tumor cells, which define a cell surface component(s), NS-1 (nervous system antigen-1), found exclusively in the nervous system. NS-1 concentrations approximate the levels of the original G26 tumor when the clonal lines are grown as clonal tumors in vivo, but are reduced when the cells are grown in vitro. NS-1 concentrations are further reduced in vitro upon incubation of the cells with 1 mM dibutyryl 3:5-cyclic AMP. H-2 histocompatibility antigen concentration, in contrast, is unaffected by dibutyryl cAMP. In addition to expressing NS-1, the neuroectodermal origin of these cell lines is further confirmed by their synthesis of the nervous system specific acidic protein S-100 and by the high specific activity of the enzyme 2:3-cyclic nucleotide 3-phosphohydrolase. In addition, they respond to catecholamines by the elevation of intracellular 3:5-cyclic AMP levels. Whereas expression of S-100 protein is high under in vitro conditions but negligible after one passage in vivo, 2:3-cyclic nucleotide 3-phosphohydrolase is not detectable in vitro but becomes detectable again in vivo. The two membrane-bound constituents, NS-1 and 2:3-cyclic nucleotide 3-phosphohydrolase, therefore seem to be subjected to different regulatory mechanisms from that of the soluble, intracellular S-100 protein.
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PMID:Biochemically differentiated mouse glial lines carrying a nervous system specific cell surface antigen (NS-1). 16 83

Literatures showed that cyclic AMP of cultured neoplastic cells of any kind was very low in concentration and also the effect of cyclic AMP and its derivatives on the malignant cells, especially on the malignant glioma, was already reported in vivo or in vitro from several neurosurgical units. The intrinsic content of cyclic AMP of the human cerebrum and the human brain tumors was first reported by authors in 1971. In this presentation the authors intended to confirm that the lower concentration of the cyclic AMP the more histologically malignant cerebral neoplasm, as well as in the cerebrospinal fluid, was observed. Concentration of cyclic AMP in the subcortical white matter, glioma, meningioma and medullobalstoma was much lower than in the gray matter tissue, however, it was not clear that the difference of the cyclic AMP concentration be possibly related to the malignancy of the human brain tumor. Furthermore, the cyclic AMP content of the cerebrospinal fluid of the patients with various brain tumor was not clearly different. The activity of adenyl cyclase was reported the highest in the synaptosome-containing fraction of the rat brain homogenate and this fact was significantly consistent with the finding that the highest concentration of the cyclic AMP was found in the human grey matter tissue. With the human brain gray matter authors determined successfully the activity of the human cerebral phosphodiesterase, which was probably localized in the post-synaptic membrane and was 158 nmole/mg protein/min. Its apparent Km was 0.9 x 10(-4) M. The results reported above have suggested the important participation of the cyclic AMP to cerebral synaptic transmission of nerve impulses, which was studied by light and electron-microscopic autoradiography utilizing the pulse labeling method with 3H-adenine. According to our study the majority of the adenyl cyclase of the human cerebrum was located synaptic structure and the finding obtained was quite compatible, as the first morphological study, with previously reported biochemical analyses. It was indicated that the cyclic AMP in the human brain was concerned to the cerebral synaptic transmission of nerve impulses and this should be very interesting and important to the clinical application for recovering cerebral function of neurosurgical patients.
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PMID:[Studies on cyclic 3', 5'-AMP system in human brain and its clinical application in Neurosurgical practice (author's transl)]. 17 18

Six clones from methylnitrosourea (MNU) or ethylnitrosourea (ENU) induced tumours obtained in the nervous system of the rat were cultured in serum-free medium or treated with dibutyryl cyclic AMP (db cAMP) in vitro. All clones originated from longterm cultures. Three clones forming sarcomas after syngeneic transplantation showed only very slight changes following treatment, whereas the three glioma clones showed striking alterations. They formed long processes or showed rounding of their perikarya. In serum-free medium the cellular shape is intermediate between that seen in normal conditions and the seen in db cAMP treated cultures. The altered cultures resemble the primary cultures of the respective tumours. The relationship of these alterations to tumour types are discussed.
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PMID:Differential morphological reaction of experimental CNS tumour clones in vitro to dibutyryl cyclic AMP or serum-free medium, resp. 17 29

Rat glioma cells in culture (subclone C6-SK71) respond to 0.1 mM noradrenaline by a 100 fold elevation of the intracellular cyclic AMP concentration, and by a subsequent change in morphology. The glioma cells extend multiple processes to resemble the morphology of normal astrocytes in brain tissue. Evidence is presented that the responses are mediated by way of a beta-adrenergic receptor. Both the biochemical and the morphological responses to noradrenaline are visible within minutes, but the cells revert to the untreated condition within 8 hours. Addition of fresh noradrenaline does not alter the sequence of events. A refractory period in which neither effect could be evoked by a subsequent exposure to noradrenaline was observed to last about 50 hours and was not correlated with a change in the rate of cell growth.
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PMID:Noradrenaline-refractoriness in cultured glioma cells. 18 16

Catecholamines cause an elevation of both cyclic GMP and cyclic AMP levels in the rat C-6 glioma cell line. The response is mediated by a beta-receptor, with a Ka for stimulation of cyclic GMP of 2.6 X 10(-7)M. Maximum levels of cyclic GMP are reached by 5 min. whereas cyclic AMP levels are maximal by 10 min. Removal of calcium decreases the cyclic GMP elevation by 60%. Refractoriness to a second treatment with catecholamine develops for both responses. Catecholamine sensitivity of the cyclic GMP-generating system appears in the cells only as they start to contact and enter the stationary growth phase. In contrast to the effects of catecholamines, cholinergic agonists have no effect on either cyclic GMP or cyclic AMP levels.
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PMID:Catecholamine-mediated elevation of cyclic GMP in the rat C-6 glioma cell line. 18 27


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