Sex-related differences in gene expression in neonatal rat hypothalamus assessed by cDNA microarray analysis.

Sexual differentiation of the rodent brain is recognized to involve transcriptional activation of multiple genes induced by gonadal steroids at developmental stages. To identify the genes differing in expression level between sexes, we analyzed gene expression in male and female rat hypothalami at postnatal day 5 by means of a cDNA microarray consisting of 2352 genes. By comparing the expression pattern between sexes, we identified 12 male-enriched genes and 20 female-enriched genes. Among them, the expression pattern of 1 male-enriched gene, jagged homolog 1, and those of 2 female-enriched genes, p27Kip1 and p130, were confirmed to be consistent with microarray data by RT-PCR. Investigation of these genes should help to elucidate the molecular and cellular mechanisms underlying sexual differentiation of the rodent central nervous system.