Effect of transient cerebral ischemia on the expression of receptor for advanced glycation end products (RAGE) in the gerbil hippocampus proper

The receptor for advanced glycation end products (RAGE) is a multi-ligand receptor of the immunoglobulin superfamily that has been implicated in multiple neuronal and inflammatory stress processes. In this study, we examined changes in RAGE immunoreactivity and its protein levels in the gerbil hippocampus (CA1-3 regions) after 5 min of transient global cerebral ischemia. The ischemic hippocampus was stained with cresyl violet, neuronal nuclei (a neuron-specific soluble nuclear antigen) antibody and Fluoro-Jade B (a marker for neuronal degeneration). 5 days after ischemia-reperfusion, delayed neuronal death occurred in the stratum pyramidale of the CA1 region. RAGE immunoreactivity was not detected in any regions of the CA1-3 regions of the sham-group; the immunoreactivity was markedly increased only in the CA1 region from 3 days after ischemia-reperfusion. On the other hand, RAGE immunoreactivity was newly expressed in astrocytes, not in microglia. Western blot analysis showed that RAGE protein level was highest at 5 days post-ischemia. In brief, both the RAGE immunoreactivity and protein level were distinctively increased in astrocytes in the ischemic CA1 region from 3 days after transient cerebral ischemia. These results indicate that the increase of RAGE expression in astrocytes after ischemia-reperfusion may be related to the ischemia-caused activation of astrocytes in the ischemic CA1 region.