Expression of c-fos, p53, Transforming Growth Factor-beta1 and Glial Fibrillary Acidic Protein in Hippocampus Following Transient Forebrain Ischemia in Mongolian Gerbil

Lee, Jae Hwa; Hur, Bang

Abstract

BACKGROUND: Recent studies have shown that delayed neuronal death is closely associated with early gene (c-fos or c-jun)-related apoptosis in addition to hypoxia-induced energy deficiency in the hippocampus.
METHODS
To elucidate the role of c-fos, p53, TGF-1 and glial fibrillary acidic protein (GFAP) and their interactions, cellular expression with immunohistochemistry was examined during the time period of 10-minute hypoxia with variable reperfusion intervals in the mongolian gerbil hippocampus.
RESULTS
Hippocampal CA1 shows progressive and delayed neuronal damage beginning from the 24-hour reperfusion, while CA2-3 reveals non-progressive, eosinophilic inclusion body within the neuron throughout the time period. CA1 neurons show short-term expressions of c-fos prior to significant cellular damage. However, CA2-3 neurons show persistent expressions by 3-day reperfusion. In both CA1 and CA2-3, p53 is expressed for the short-term period of the early time points. However, its intensity and duration are much less in CA2-3 than in CA1. While TGF-1 is transiently expressed at 24-hour reperfusion in CA1, its expression in CA2-3 is persistent in late time points. Early expression of GFAP is observed in the pyramidal layer of CA1 prior to neuronal damage and progressively increased in the late time points.
CONCLUSION
These results suggest that c-fos and TGF-1 may play a role in neuronal viability in the early- and late time points. Astrocytes may also be responsible for the active protective mechanism to neuronal death, as well as reactive gliosis. The hypoxia-induced neuronal damage is, in part, a p53-dependent process in the CA1 neurons.