Neurogenesis and synaptic plasticity in the hippocampus of rats submitted to maternal separation and environmental enrichment

Author(s)

Suélen Merlo

• Document type: Doctoral Thesis
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina de Ribeirão Preto (PCARP/BC)
• Defense date: 2014-10-23

Examining board members

Jorge Eduardo Moreira; Aldo Bolten Lucion; Luiz Eugênio Araujo de Moraes Mello

• Advisor: Jorge Eduardo Moreira

Abstract

Stressful events during childhood promote persistent behavioral and brain changes, increasing the predisposition to psychiatric disorders. The maternal separation has been used as postnatal stress model. Animals subjected to maternal separation exhibit an exaggerated response of the hypothalamus-pituitary-adrenal axis to stress. Instead, studies suggest that environmental enrichment, by increasing neurogenesis in the dentate gyrus of the hippocampus, has beneficial effects on behavioral disorders. In this project, we discuss whether the environmental enrichment interferes with plastic changes promoted by maternal separation in the hippocampus of young rats. We used immunofluorescence, confocal microscopy, electron microscopy and qRT-PCR of samples collected by a laser microdissection system. The maternal separation reduced hippocampal neurogenesis, as well as the mRNA expression for the genes Nr3c1, that codify glycocorticoid receptors, and Htr1a, that codify serotonin receptors (5HT-1A). Environmental enrichment reduced the expression of Htr1a. Furthermore, increases the proportion of synapses on dendritic spines, suggesting greater synaptic plasticity. The environment enrichment of the animals subjected to maternal separation increased cell survival and the expression of Nr3c1 mRNA, but not the neuronal differentiation in the hippocampus. The changes promoted by maternal separation are persistent, however may be partially reversed by the environmental enrichment. (AU)

• FAPESP's process: 10/18446-7 - The study of neurogenesis and synaptic plasticity in rats submitted to the maternal separation and enriched environment
• Grantee: Suelen Merlo
• Support Opportunities: Scholarships in Brazil - Doctorate