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M Colasanti

Publications and source records attributed to M Colasanti.

46 records · Page 3Linked to original sources
PubMed1995

NMDA-dependent prostaglandin E2 release by human cultured astroglial cells is driven by nitric oxide.

The role of the L-arginine-NO pathway on the formation of PGE2 by human cultured astroglial cells incubated with NMDA has been investigated. Preincubation of T 67 astroglial cell line with NMDA (10-600 microM) produced a significant dose-dependent increase of both nitrite (the breakdown product of NO), PGE2 and cGMP levels in cell supernatant. This effect was inhibited by coincubation of cells with L-NAME (20-300 microM), an inhibitor of NO synthase showing that the release of PGE2 subsequent to NMDA receptor stimulation was driven by NO. The release of PGE2 but not elevation of nitrite and cGMP levels was affected by indomethacin (10 microM), an inhibitor of cyclooxygenase. The inhibitory effect of L-NAME on PGE2 release by NMDA-pretreated astroglial cells was reverted by arachidonic acid, showing that the effect of NO on PGE2 release occurred at the cyclo-oxygenase level. Thus, the present experiments demonstrate that the release of PGE2 by astroglial cells pretreated with NMDA is driven by activation of the L-arginine-NO pathway, and this may be relevant in the pathophysiological mechanisms where glutamatergic neurotransmission is involved.

Arachidonic Acid↗
PubMed1995

Inhibition of inducible nitric oxide synthase mRNA expression by basic fibroblast growth factor in human microglial cells.

The effect of basic fibroblast growth factor (bFGF) on inducible nitric oxide synthase (iNOS) mRNA expression in human cultured ramified microglial cells was investigated. Using RT-PCR and Southern blot analysis, we found that bFGF prevented the iNOS gene expression as induced by LPS/TNF alpha. Also, bFGF dose-dependently inhibited nitrite levels in treated cell supernatants. That the early presence of bFGF during LPS/TNF alpha induction was essential indicates that iNOS gene expression can be transcriptionally regulated.

Blotting, Southern↗
PubMed1994

NMDA-dependent NGF mRNA expression by human astrocytoma cells is mediated by nitric oxide.

The aim of this study was to investigate the role of NO-cGMP pathway in NMDA-induced NGF mRNA expression by T67 astrocytoma cells. Levels of nitrite, a breakdown product of NO, in supernatants of NMDA-treated astrocytoma cells were significantly higher compared with control cells, this effect being reversed by the specific NO synthase inhibitor L-NAME. Furthermore, NGF mRNA expression was induced by NMDA treatment, this effect being inhibited by pretreating cells with L-NAME. Moreover, methylene blue, an inhibitor of NO biological activity at guanylate cyclase level, inhibited NMDA-induced NGF mRNA expression and this effect was reversed by dbt2-cGMP. These findings suggest that NO-cGMP pathway mediates the synthesis of NGF mRNA.

Astrocytoma↗
PubMed1994

HIV coating gp 120 glycoprotein-dependent prostaglandin E2 release by human cultured astrocytoma cells is regulated by nitric oxide formation.

The role of the L-arginine-NO pathway on the formation of PGE2 by cultured astroglial cells incubated with the HIV coating glycoprotein gp120 was investigated. Preincubation of human cultured T 67 astrocytoma cells with gp 120 (100-500 nM) produced a significant increase of nitrite (the breakdown product of NO) and PGE2 in cell supernatants. The effect of gp 120 on both nitrite and PGE2 production was antagonized by inhibition of NO synthase by L-NAME (20-300 microM). The inhibition of gp120-induced PGE2 production by L-NAME was reverted by addition of arachidonic acid (30 microM), an effect antagonized by the cyclo-oxygenase inhibitor indomethacin (10 microM). Methylen bleu, an inhibitor of the biological activity of NO acting at the guanylate cyclase level failed to affect gp 120-mediated PGE2 release showing that the increase of cGMP subsequent to NO production was not involved in the modulatory activity of NO on arachidonic acid cascade. On the basis of present experiments we conclude that gp-120-induced release of PGE2 by astroglial cells is driven by NO, thereby contributing in the involvement of glial cells in HIV-related cerebral disorders.

Amino Acid Oxidoreductases↗
PubMed1994

Interferon gamma up-regulates alpha 2 macroglobulin expression in human astrocytoma cells.

An established human astrocytoma cell line (T67) was shown to constitutively produce the proteinase inhibitor alpha 2 macroglobulin (alpha 2M). Interferon gamma (IFN gamma), a potent immunoregulatory lymphokine, was able to increase the synthesis of alpha 2M by these cells, as measured by ELISA on cell supernatants. The alpha 2M induction was also observed in other human glioma cell lines (T70 and ADF) and in human fetal astrocyte cultures following IFN gamma treatment. In T67 cells this effect was dose-dependent and the maximum (2.7-fold increase) was obtained with 2000 U/ml of IFN gamma. A corresponding enhanced alpha 2M mRNA accumulation was demonstrated by PCR and Northern blot techniques. Our results suggest an important role of alpha 2M during inflammatory and immune processes in the CNS. An increased release of alpha 2M following IFN gamma stimulation may allow the removal of the bulk of proteases released at the site of inflammation, strengthening at the same time the antigen presentation processes.

Astrocytoma↗
PubMed1993

HIV gp120 glycoprotein stimulates the inducible isoform of no synthase in human cultured astrocytoma cells.

The effect of the HIV coating glycoprotein gp 120 on the generation of NO by human cultured T67 astrocytoma cells was investigated. Preincubation of astrocytoma cells with gp 120 (10 pM, 100 and 500 nM) produced a significant, dose-dependent increase of nitrite levels in supernatant of pretreated cells which was higher when compared to untreated cells. This effect was prevented by coincubation of cells with monoclonal antibodies directed against gp 120, or by pretreatment of cells with the selective NO synthase inhibitor L-NAME (100 microM). The rise of nitrite following pretreatment of astrocytoma cells with gp 120 was accompanied by an increase in NO synthase activity which was mainly Ca(++)-independent. Also this effect was inhibited by antibodies against gp 120, showing the specificity of the activation of the L-Arg-NO pathway subsequent to incubation of astrocytoma cells with the HIV coating protein. In conclusion, the present results are consistent with an activation of the inducible, Ca(++)-independent isoform of NO synthase in cultured astrocytoma cells following coincubation with gp 120. This may contribute to explain some of the neuropathological changes accompanying HIV-related cognitive disorders.

Amino Acid Oxidoreductases↗
PubMed1993

Cytokine-induced nitric oxide generation by cultured astrocytoma cells involves Ca(++)-calmodulin-independent NO-synthase.

The effect of several cytokines (IL1 beta and TNF alpha) on the inducible biosynthesis and release of NO by cultured astrocytoma cells was investigated and compared to that observed following pretreatment of cells with LPS. Preincubation for 4, 12, 24 and 48 h of astrocytoma cells with IL1 beta (10 ng ml-1), TNF alpha (500 U ml-1) and LPS (0.5 micrograms ml-1) enhanced their ability to inhibit thrombin-induced platelet aggregation through the release of an NO-like factor and increased nitrite levels in supernatants of stirred cells. The enhancement of NO production induced by cytokines as well as LPS was mediated by a time-dependent increase of NO-synthase activity in cell homogenates being mainly Ca(++)-calmodulin-independent. However, LPS activated earlier than cytokines the inducible NO-synthase and its effect was, at least in part, related to the release of IL1 beta by astrocytoma cells. In conclusion, the present data show, for the first time, that astrocytoma cells possess a cytokine-inducible Ca(++)-calmodulin-independent NO-synthase, whose activation seems to occur with a mechanism different from that described for LPS.

Amino Acid Oxidoreductases↗
PubMed1993

The generation of nitric oxide participates in gamma IFN-induced MHC class II antigen expression by cultured astrocytoma cells.

The effects of interferon gamma (gamma IFN) on the MHCII antigen expression by human cultured astrocytoma cells were investigated. The co-incubation of gamma IFN with T67 astrocytoma cells produced a dose-dependent increase of MHCII antigen expression as evaluated by flow cytometric (FACS) analysis and confocal laser microscopy analysis. The number of MHCII molecules expressed by gamma IFN-pretreated astrocytoma cells was reduced by co-incubation with N omega-nitro-L-arginine methyl ester (L-NAME), a selective inhibitor of the nitric oxide (NO)-synthesizing enzyme. In addition, methylene blue, which inhibits the biological activity of NO acting at the guanylate cyclase level, strongly antagonized the MHCII antigen expression on astrocytoma cells induced by gamma IFN. Furthermore, gamma IFN increased the activity of the inducible isoform of NO-synthase as well as the concentration of nitrite, one of the breakdown products of NO and the antiplatelet activity of astrocytoma cells. In conclusion, the present data show that gamma IFN increases the synthesis and release of NO by cultured astrocytoma cells and this could co-participate in the MHCII antigen expression by this cell type. Therefore, the generation of NO by cultured astrocytoma cells may represent an important step in the development of the immunocompetent activity of astrocytes.

Amino Acid Oxidoreductases↗
PubMed1991

Different in vitro response to rIL-1 beta of newborn and adult rat astroglia.

In recent literature, lymphokines have been reported to be able to promote both proliferation and maturation of some glial populations. In this paper, we compare the effect of rIL-1 on newborn and adult rat astroglial cells in vitro. In newborn, but not in adult astrocytes, 100 U/ml of rIL-1 beta increase [3H]thymidine incorporation with a maximal response by 3 days as compared to the control untreated culture. In contrast, rIL-1 beta induces an increase of GFAP immunoreactivity both in newborn and in adult astrocytes, as compared to the control untreated cells. These data indicate that, while both newborn and adult astroglial cells are capable of responding to rIL-1 beta, only newborn astrocytes can respond to this lymphokine with proliferation. Thus, it appears likely that different factors, other than rIL-1 beta, are needed by adult astrocytes to proliferate.

Aging↗