GLUCOCORTICOID REGULATION OF IN-VITRO ASTROCYTE PHAGOCYTOSIS

Astrocytes participate in central nervous system injury, degenerative diseases and also perform macrophagic functions. The present work inve stigates: 1) the effect of the physiological glucocorticoid corticoste rone (CORT) and the synthetic agonist dexamethasone (DEX) on latex bea ds phagocytosis by neonatal rat cortical astrocytes in culture, and 2) tile expression of immunoreactive glucocorticoid receptors (GR) in as trocytes cultured in different media with or without a pulse applicati on of CORT. The results indicated that glucocorticoids reduced astrocy te phagocytic activity, as occurred with macrophages, independently of the culturing conditions employed. The extent of phagocytosis was inv ersely related to nuclear immunostaining for GR in cultures in fetal c alf serum, which contained endogenous glucocorticoid. However, no corr elation was found between nuclear GR and phagocytosis for cultures in glucocorticoid-free medium or in medium containing CORT. It is suggest ed that additional factors, besides the GR, may be involved in glucoco rticoid modulation of astrocyte phagocytosis.