Studies on GSK 3 ¥ â expression in the kainate induced excitototoxic hippocampal injury model of mice

Studies on GSK3¥â expression in the kainate induced excitototoxic hippocampal injury model of mice Jung Hoon Lee Department of Anatomy Graduate School Seoul National University Glycogen synthase kinase 3¥â (GSK3¥â) is believed to play important roles in the regulation of synaptic plasticity, cell survival and circadian rhythms in the mature CNS. However, although several studies have been focused on the GSK3¥â, little is known about GSK3¥â expression in glial cells under neuropathological conditions. In this study, we evaluated the expressions of molecules associated with the GSK3¥â signaling pathway, following the induction of an excitotoxic lesion in mouse brain by kainic acid (KA) injection, which caused pyramidal cell degeneration in the hippocampal CA3 region. In injured hippocampi, Ser47-Akt (protein kinase B, PKB) phosphorylation increased from 4 h until 1 day post-injection (PI). Ser9-GSK3¥â and Ser133-cAMP responsive elementbinding protein (CREB) phosphorylations showed similar spatiotemporal patterns in hippocampi at 1 day until 3 days PI. Double immunohistochemistry also showed that these phosphorylated forms of Akt, GSK3¥â and CREB were expressed in astrocytes. For the first time, our data demonstrate the injury-induced astrocytic expressions of phospho-Akt, -GSK3¥â and -CREB in vivo, which reflect mechanisms of glial cells protection or adaptive response to damage. We consider that these expressions may be of importance during the evolution of glial response and in psychiatric disorders.