cDNA microarray analyses on the gene expression in the pituitary glands under the physiological and experimental conditions.

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The pituitary gland is situated in the center of hypothalamic-pituitray-gonadal axis that cooperatively regulates the reproductive functions. Pituitary gonadotropes regulate the gonadal function by secreting two gonadotropins, LH and FSH, and in turn, their functional states are influenced by the hypothalamic and gonadal factors. To describe the molecular basis of these influences on the pituitary gland, we analyzed simultaneously the expression levels of 11,505 genes in the rat pituitary and adrenal glands under the physiological and experimental conditions by using a cDNA microarray.First, we found significant sex-related differences in the expression levels of 112 genes in the pituitary and 87 genes in the adrenal glands. Interestingly, only 4 genes of the 112 genes identified above in the pituitary exhibited simultaneously a significant sex-related difference in the expression in the adrenal, suggesting that the molecular basis for the sex-related differences varies depending on th … More e tissues/cells. These sex-related differences in the gene expression are significantly reduced after castration (orchiectomy for male, and ovariectomy for female rats), indicating that the gonadal factors play a pivotal role in the establishment of sex-related differeneces in these two organs. However, the gene expression of these two endocrine organs were differently regulated by androgens and estrogens ; the expression levels of about three fourths of the 112 genes identified above in the pituitary were significantly fluctuated by estradiol treatment after castration in correspondence with the sex-related difference observed, while those of four fifths of the 87 genes identified above in the adrenal were significantly fluctuated by testosterone treatment.These analyses first clarified the molecular basis of sex-related differences in the two representative organs, pituitary and adrenal glands. Based on these findings, the gene products that have not been classified so far could be identified as a molecule with a significant function in the hypothalamic-pituitary-gonadal axis. Less