NEUROACTIVE STEROIDS REGULATE ASTROGLIA MORPHOLOGY IN HIPPOCAMPAL CULTURES FROM ADULT-RATS

Recent evidence indicates that astroglia may be involved in the synthe sis of endogenous neurosteroids. The extension of glial fibrillary aci dic protein (GFAP)-immunoreactive astroglial cell processes was assess ed in hippocampal slice cultures from adult gonadectomized male rats u nder the influence of the neurosteroids dehydroepiandrosterone, dehydr oepiandrosterone sulfate, dehydroepiandrosterone estereate, pregnenolo ne, pregnenolone sulfate, and pregnenolone oleate. The effects of neur osteroids were compared to those induced by the gonadal steroids testo sterone, 17 beta-estradiol and progesterone. Astrocytes in hippocampal slice cultures had a morphology that was indistinguishable from that observed in the hippocampus fixed in situ. Castration of adult male ra ts resulted in a significant decrease in the extension of GFAP-immunor eactive processes, both in tissues fixed in situ and in slice cultures . In contrast, incubation of slice cultures from gonadectomized animal s with pregnenolone, pregnenolone sulfate, 17 beta-estradiol, and test osterone enhanced the extension of GFAP-immunoreactive processes. Whil e other steroids tested did not affect this parameter, dehydroepiandro sterone and its sulfate and estereate derivatives induced the transfor mation of astroglial cells into hypertrophic and highly GFAP immunorea ctive cells with the morphological characteristics of reactive astrogl ia. We conclude that neurosteroids regulate the morphology and/or GFAP distribution of astrocytes in hippocampal slice cultures from adult r ats. (C) 1995 Wiley-Liss, Inc.