Abstract
Estrogen influences on many basic molecular and cellular events in the brain of rats. Exposure of the developing brain to estrogen during the critical periods results in profound changes in morphology. In order to examine key factors, which are regulated by estrogen and induce sexual dimorphism in the brain, we focused on the expression of genes in the sexually dimorphic nucleus (SDN) and the anteroventral periventricular nucleus (AVPvN) of the preoptic area. Female rats injected with 100 μg 17β-estradiol on the day of birth or without injection were sacrificed 2 or 5 days later. Total RNA from SDN or AVPvN was subjected to analysis using a focused microarray (EstrArray), which consists of 173 estrogen-responsive rat genes. Microarray analysis was carried out three times to evaluate its accuracy and reproducibility, and revealed that 28 genes showed significant differences in the gene expression profiles between the tissues and the postnatal days. The major functional categories analyzed here included apoptosis, migration, nervous system development, cell growth and metabolism. The set of apoptosis-related genes showed significant correlations between the tissues and the postnatal days. These genes were also examined by real-time RT-PCR analysis. Among the apoptosis-related genes, Yars, c-Jun, Nckap1, and Prkcd were up-regulated in AVPvN more than SDN. These results suggest that the regulation of apoptosis-related genes by estrogen is a cue to induce the sexual differentiation of the rat brain during the critical periods. [J Physiol Sci. 2007;57 Suppl:S174]
