Dexamethasone Up-Regulates a Constitutive Nitric Oxide Synthase in Cerebellar Astrocytes but Not in Granule Cells in Culture |
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Authors: | Maria Antonia Baltrons Luis Agulló Agustina García |
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Institution: | Instituto de Biología Fundamental "V. Villar Palasí" and Departamento de Bioquímica y Biología Molecular, Universidad Autónoma de Barcelona, Bellaterra, Spain |
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Abstract: | Abstract: Treatment of rat cerebellar astrocyte-enriched primary cultures with dexamethasone enhances the nitric oxide-dependent cyclic GMP formation induced by noradrenaline in a time-(>6 h) and concentration-dependent manner (half-maximal effect at 1 n M ). Stimulation of cyclic GMP formation by the calcium ionophore A23187 is similarly enhanced. In contrast, cyclic GMP accumulation in cells treated with lipopolysaccharide is inhibited by dexamethasone. The potentiating effect of dexamethasone is prevented by the protein synthesis inhibitor cycloheximide and is not due to increased soluble guanylate cyclase activity. Agonist stimulation of 3H]arginine to 3H]citrulline conversion is enhanced by dexamethasone in astrocytes but not in cerebellar granule cells. These results indicate that glucocorticoids may up-regulate astroglial calcium-dependent nitric oxide synthase while preventing expression of inducible nitric oxide synthase and are the first report of a differential long-term regulation of the expression of neuronal and astroglial constitutive nitric oxide synthase activities. |
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Keywords: | Astrocytes Neurons Cerebellum Nitric oxide Cyclic GMP Noradrenaline |
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