THYROID-HORMONE ACTION ON ASTROGLIAL CELLS FROM DISTINCT BRAIN-REGIONS DURING DEVELOPMENT

Astrocytes are target to triiodothyronine (T3) hormone action during r at brain development. In this work, we show that astrocytes from disti nct developing brain regions are differently responsive to thyroid hor mone. Distinctly from embryonic or newborn cerebral hemisphere and mes encephalic astrocytes, newborn cerebellar and embryonic hippocampal as trocytes do not change their morphology in response to hormone treatme nt. We also analysed protein synthesis and secretion from these T3-tre ated astrocytes. The results showed a significant increase in protein synthesis in astrocytes from older brain regions. Maximum effect, howe ver, was observed in cerebral hemisphere astrocytes from newborn rats. The protein secretion effect was also more evident in the cerebral he misphere as well as in cerebellar astrocytes from newborn rats. In add ition, we examined T3 effects on GFAP/vimentin expression by culturing 6-day old cerebellar astrocytes. In this case T3 seems to induce GFAP expression which might be occurring as a first step to astrocyte diff erentiation. (C) 1998 ISDN. Published by Elsevier Science Ltd.