Status epilepticus induces long lasting increase in S100A6 expression in astrocytes

In the present work we examined expression and localization of the S100A6 protein in rat brain in a model of epilepsy induced by Status Epilepticus evoked by amygdala stimulation. We demonstrate, through the use of the reverse transcriptase-polymerase chain reaction technique, that mRNA level of S100A6 was increased in cortex while, as found by immunoblotting, the level of the S100A6 protein was significantly higher in the cortex and in the CA1 area of the hippocampus at day 14 after stimulation. Immunohistochemical studies performed on rat brain slices indicated that S100A6 immunoreactivity was elevated in GFAP-positive astrocytes in the hippocampus and cortex starting from day 1, and further increased at day 4 and 14 after stimulation. Interestingly, in a subpopulation of astrocytes, up-regulation of S100A6 was associated with an increased level of β-catenin, a protein involved in regulation of S100A6 expression. Altogether, our data show a widespread and prolonged up-regulation of S100A6 in the epileptic brain and indicate that an increase in S100A6 immunoreactivity is related to astrogliosis.