Different cortical and subcortical astroglial responsiveness in rats with acute liver failure

Hepatic encephalopathy (HE) is a neuropsychiatric complication of liver failure. Previous studies described astroglia alterations in HE, but regional changes have not been well investigated. This study addresses regional astroglial response by exploring glial fibrillary acidic protein (GFAP) immunoreactivity in cortical structures including somatosensory (S1Tr and S1BF), piriform (Pir), and perirhinal (PRh) cortices, and subcortical regions including corpus callosum (CC), ventromedial thalamus (VMT), mammillothalamic tract (MTT), and dorsomedial hypothalamic nucleus (DHN) in rats with acute liver failure (ALF) sacrificed at coma stage. Our data showed decreased numbers of astrocytes in S1Tr, Pir, and CC in ALF rats. GFAP-immunoreactive cells were increased within other regions including PRh, VMT, MTT, and DHN. Cell morphometric analysis showed significant increase in GFAP-immunoreactive astrocyte processes and cell bodies in cortical and subcortical regions but not in CC and DHN. However, astrocyte perimeters were increased, particularly in S1Tr and VMT. Our study demonstrates regional specificity including (1) regions with astrocyte activation associated with an increase of GFAP-immunostaining and astrocyte cell counts, together with (2) unaltered GFAP components, and (3) regions characterized by presumably inactive astrocyte with a reduced GFAP-immunostaining. These findings may reflect either different regional alterations in HE, or stages of an alteration progressing differently in different regions.