Prefrontal cortex and hippocampus of young adults rats subjected to maternal separation and environmental enrichment: recovery of postnatal stress?

Abstract

Maternal separation is an animal model to neonatal stress. It is of great interest the study of brain changes promoted by maternal separation, and whether they can be reversed or attenuated by environmental enrichment. Decrease of the prefrontal cortex or hippocampus volumes observed in schizophrenic or chronically depressed patients may be partly due to a reduction in neurogenesis and/or increased apoptosis. Studies from our laboratory showed reduction of the neurogenesis in the hippocampus of young rats subjected to maternal separation. Because the prefrontal cortex is not considered a neurogenic region in adults, a possible decrease of its volume in these animals could be caused by reduction in number of neurons and/or glial cells in this region, possibly by increased apoptosis. Furthermore, since calcium binding proteins have essential role in the processes of neurogenesis and programmed cell death, it would be important to study changes in these proteins in the hippocampus and prefrontal cortex of animals subjected to maternal separation followed by environmental enrichment. Synaptic changes, seeing in hippocampi of animals subjected to those procedures might be extended to the prefrontal cortex. The absence of changes in the areas immunopositive for GFAP in the hippocampus of animals subjected to both procedures did not rule out the role of astrocytes in the processes of neural plasticity and excitotoxicity. Thus, it would be important to study the molecular changes in glial and neuronal levels of glutamate transporters in the hippocampus of these animals. (AU)