Neurogenesis and synaptic plasticity in the hippocampus of rats submitted to the maternal separation and enriched environment

Abstract

The maternal separation, considered for many researchs as a model of depression and postnatal stress, promotes several behavioral and brain changes. Animals submitted to the maternal separation have, during adulthood, incresead responses of the HPA axis to stress stimuli, reduction of the hippocampal neurogenesis and reduction of the desinty of dentritic spines in several brain structures. The enriched environment increases the neurogenesis in the dentate gyrus of the hippocampus, with beneficial effects in behavioral disorders. The present project will be conducted to test the hypothesis that the enriched environment can attenuate some cerebral changes promoted by maternal separation. Pregnant rats will be accompanied daily and the pups will be isolated from their mothers 3 h per day from the 1º to 14º postnatal day. After weaning (day 21), the pups will be submitted to the enriched environment, one environment where the animals will have more opportunities to social interaction, physical exercise and more opportunities for learning. The hippocampus of adolescent and adult animals (submitted or not to the maternal separation and to the enriched environment) will be removed for the analysis of the neurogenesis and apoptosis in the hippocampal neuronal cells. In addition, the number and morphology of dendritic spines as well as the expression of protein and mRNA for glucocorticoid receptors will be analyzed in the dorsal and ventral hippocampus of the animals from all experimental groups. (AU)