Icam5 expression exhibits sex differences in the neonatal pituitary and is regulated by estradiol and bisphenol A

Endocrine-disrupting chemicals are prevalent in the environment and can impair reproductive success by affecting the hypothalamic-pituitary-gonadal axis. The developing pituitary gland is sensitive to exposure to endocrine-disrupting chemicals, such as bisphenolA(BPA), and sex-specific effects can occur. However, effects on the critical window of neonatal pituitary gland development in mice have not been explored. Therefore, this study determined baseline gene expression in male and female pituitaries and consequences of environmental exposure to 17β-estradiol (E2) and BPA on transcription of genes exhibiting sex differences during the neonatal period. Through microarray and quantitative RT-PCR analysis of pituitaries at postnatal day (PND)1, 3 genes were differentially expressed between males and females: Lhb, Fshb, and intracellular adhesion molecule-5 (Icam5). To see whether E2 and BPA exposure regulates these genes, pituitaries were cultured at PND1 with 10^-8ME₂ or 4.4 × 10^-6MBPA. E2 decreased expression of Lhb, Fshb, and Icam5 mRNA in females but only significantly decreased expression of Icam5 in males. BPA decreased expression of Icam5 similarly to E2, but it did not affect Lhb or Fshb. Importantly, in vivo exposure to 50-μg/ kg · d E2 from PND0 to PND7 decreased expression of Lhb, Fshb, and Icam5 mRNA in both males and females, whereas 50-mg/kg · dBPA exposure during the same time frame decreased expression of Icam5 in females only. Overall, we have uncovered that genes differentially expressed between the sexes can be regulated in part by hormonal and chemical signals in vivo and directly at the pituitary and can be regulated in a sex-specific manner.