Changes in glial fibrillary acidic protein immunoreactivity in response toexperimental hepatic encephalopathy in the rat hippocampus

The response of astroglial cells in the hippocampus to long-term portacaval anastomosis (PCA), an experimental model of hepatic encephalopathy, was st udied in adult male rats and compared with controls. Six months after PCA, the rat hippocampi were processed for glial fibrillary acidic protein (GFAP ). GFAP-immunopositive astroglial profiles were observed in all hippocampal layers in PCA rats, but GFAP distribution differed in PCA rats and control s. In PCA rats, cell bodies and cell processes immunostained with GFAP were observed mainly in the CA1-CA3 layers in relation to pyramidal neurons, wh ereas the number and length of the astroglial processes decreased in the re st of the hippocampal regions. In addition, decreased GFAP immunoreactivity in the perivascular processes was observed in PCA rats compared with contr ols. These results show that long-term PCA elicited different responses in GFAP expression in different hippocampal regions, which might suggest a reg ional variation in glial sensitivity.