Response of carp central nervous system to hyperammonemic conditions: animmunocytochemical study of glutamine synthetase (GS), glial fibrillaryacidic protein (GFAP) and 70 kDa heat-shock protein (HSP70)

摘要

Glutamine synthetase (GS), glial fibrillary acidic protein (GFAP) and 70 kDa heat-shock protein (HSP70) expression were studied in neural tissue of adult carp subjected to hyperammonemic conditions using immunocytochemical methods (immunoblotting, dot blotting, ELISA and immunocytochemistry). Carps were subjected to 1, 2 and 4 mM ammonium acetate for 7, 15, 30 and 60 days since the mortality rate was 100% at 8 mM within 2 days. The mortality rate was 27% at 4 mM. A significant dose-dependent induction of GS was observed in hyperammonemic brains. GS immunoreactivity was located in radial astrocytes and some ependymal cells. Significant increments of GFAP were observed at 30 days for 1 mM, at 15 and 30 days for 2 mM, and at 30 and 60 days for 4 mM; a heterogeneous response to hyperammonemia was observed in different brain regions. Significant increments in HSP70 were observed in hyperammonemic brain (30 days, 4 mM). The neuronal pattern of HSP70 immunoreactivity under control conditions changed to an ependymal pattern under hyperammonemic conditions. These results suggest that the main effect of hyperammonemia was GS induction in neural tissue. GFAP induction could be an effect of astroglial activation and HSP70 induction could be related with de novo protein synthesis. (C) 1999 Elsevier Science B.V. All rights reserved. [References: 61]