title: Dexamethasone induces an increase in intracellular and membrane-associated lipocortin-1 (annexin-1) in rat astrocyte primary cultures.
abstract: 1. The antiinflammatory actions of glucocorticoid steroids are thought to occur through induction of the protein lipocortin-1 (LC-1; annexin-1). The purpose of the current study was to investigate whether astrocytic LC-1 content was increased in the presence of a synthetic glucocorticoid, dexamethasone. 2. Steroid-induced changes in cellular levels of LC-1 in astrocytes were determined by electrotransfer and immunoblotting techniques. Separate cell fractions were investigated to study the influence of dexamethasone on astroglial LC-1 content. The effect of culture state on LC-1 expression was also examined. 3. Intracellular LC-1 content was found to decrease after initiation of culture, with a substantial rise in both cell proliferation and LC-1 expression occurring after the replenishment of medium containing steroid-free serum. A further increase in intracellular LC-1 occurred upon incubation with dexamethasone. The glucocorticoid-induced change in intracellular LC-1 was a time-dependent event and coincided with an increase in membrane-associated LC-1. 4. The findings in this study indicate that astrocytic LC-1 content is influenced by cell culture conditions and, in the presence of glucocorticoid steroids, the cellular localization of LC-1 is altered. This may indicate that LC-1 has functions at more than one cellular locality.
authors.affiliation: Department of Pharmacology, School of Pharmacy and Pharmacology, University of Bath, Claverton Down, England.
authors.forename: J D
authors.initials: JD
authors.lastname: McLeod
authors.forename: C
authors.initials: C
authors.lastname: Bolton
mesh_terms: D000818:Animals; D017305:Annexin A1 / Q000032:analysis / Q000096:biosynthesis*; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D003907:Dexamethasone / Q000494:pharmacology*; D005260:Female; D007150:Immunohistochemistry; D007700:Kinetics; D051381:Rats; D017208:Rats, Wistar
chemical_list: D017305:Annexin A1; D000894:Anti-Inflammatory Agents, Non-Steroidal; D003907:Dexamethasone