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Dexamethasone Up-Regulates a Constitutive Nitric Oxide Synthase in Cerebellar Astrocytes but Not in Granule Cells in Culture

Authors

  • Maria Antonia Baltrons,

    1. Instituto de Biología Fundamental “V. Villar Palasí” and Departamento de Bioquímica y Biología Molecular, Universidad Autónoma de Barcelona, Bellaterra, Spain
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  • Luis Agulló,

    1. Instituto de Biología Fundamental “V. Villar Palasí” and Departamento de Bioquímica y Biología Molecular, Universidad Autónoma de Barcelona, Bellaterra, Spain
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  • Agustina García

    Corresponding author
    1. Instituto de Biología Fundamental “V. Villar Palasí” and Departamento de Bioquímica y Biología Molecular, Universidad Autónoma de Barcelona, Bellaterra, Spain
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Address correspondence and reprint requests to Dr. A. García at Instituto de Biología Fundamental “V. Villar Palasí,” Universidad Autónoma de Barcelona, 08193 Bellaterra, Spain.

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 nM). 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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