Electroconvulsive seizure treatment increases cell proliferation in rat frontal cortex

Recent studies have demonstrated increased neurogenesis in adult hippocampus in response to electroconvulsive seizure (ECS) or antidepressant drug treatment. Adult neurogenesis in the subgranular zone of the hippocampus and the subventricular zone is well established, whereas neuronal proliferation outside of these areas under unstimulated conditions is not observed. Since mood disorders are likely to involve brain regions in addition to hippocampus, particularly the frontal cortex, it is likely that antidepressant treatments produce cellular changes in these brain regions as well. In this study, we have investigated the effect of repeated ECS administration on the proliferation of cells in the frontal cortex, and we have examined the phenotype of these cells 4 weeks after labeling with a cell division marker. We found that ECS treatment increases the number of newly divided cells in the frontal cortex and that these new cells express markers of either endothelial cells or oligodendrocytes, but not neurons. It is possible that increased proliferation of these cell types in the frontal cortex could reverse the loss of glial cell number and the reduced volume that has been reported in the frontal cortex of depressed patients.