Restraint Stress on Female Mice Diminishes the Developmental Potential of Oocytes: Roles of Chromatin Configuration and Histone Modification in Germinal Vesicle Stage Oocytes

摘要

Female mice and rats exposed to psychological restraint stress during pregnancy show impaired embryo development and reduced pregnancy rates and litter sizes. Restraint stress in female mice causes chromosome abnormalities and impairs the developmental potential of oocytes. The mechanisms underlying these effects appear to be related to changes in chromatin configuration during maturation and/or epigenetic histone modifications. Two classes of chromatin configuration occur in fully grown germinal vesicle stage oocytes: the nonsurrounded nucleolus (NSN) and the surrounded nucleolus (SN) oocytes. Histone acetylation leads to relaxation of chromatin structure and correlates with gene activation, whereas histone deacetylation leads to condensation of chromatin structure and correlates with gene repression. The relationship between oocyte growth and increased histone acetylation and methylation or that between oocyte growth and chromatin configuration and competence is unclear and can only be determined using a system where the SN configuration can be dissociated from histone modification.