Kainate-induced neuronal injury leads to persistent phosphorylation of cAMP response element-binding protein in glial and endothelial cells in the hippocampus

Intracerebroventricular kainate treatment in rats induces neuronal cell death, followed by proliferation and hypertrophy of glial cells in the lesioned area. To further understand the activated signal transduction pathways and to get insights into potential target gene activation, the present study aims to elucidate long-term effects on the phosphorylation state of cAMP response element-binding protein (CREB) in the hippocampal formation. One to four weeks after kainate injection, we found high levels of phosphorylated and hence activated CREB (pCREB) in glial cells of the degenerating CA fields. As shown by electron microscopy, pCREB immunoreactivity was present in reactive astrocytes, oligodendrocyte precursor cells and endothelial cells of blood vessels. It is postulated that pCREB could drive the expression of downstream genes in these cells to promote cell proliferation and survival.