Glucocorticoids modulate the cellular disposition of lipocortin 1 in the rat brain in vivo and in vitro.

The role of glucocorticoids in the regulation of lipocortin 1 (LC1) mRNA/protein expression in the brain is uncertain. This study has examined the influence of dexamethasone on the disposition of LC1 protein in various central and peripheral tissues in the rat. LC1 was readily detectable in all tissues studied by Western blot analysis. Exposure to dexamethasone in vitro (0.1 microM, 3 h) or in vivo (20 micrograms/100 g i.p., 24 h before autopsy) had no discernible effects on intracellular LC1 levels but increased the amount of LC1 attached to the outer surface of cells (pericellular LC1) in cortex, hippocampus, hypothalamus, pituitary gland and peritoneal macrophages (in vitro only). The results suggest that in central tissues, as in the periphery, glucocorticoids promote the translocation of LC1 from intracellular to pericellular sites.