Differential Expression Patterns of Wnt and b-Catenin/TCF Target Genes in the Uterus of Immature Female Rats Exposed to 17a-Ethynyl Estradiol

To characterize the effects of an estrogen receptor (ER) agonist on the gene expressions in the uterus, immature female rats were administered once orally with 17a-ethynyl estradiol (EE, 3 mg/ kg), a potent ER agonist. We focused on four categories of sex steroid hormone receptor genes: well-known estrogen target genes, Wnt genes, and b-catenin/T-cell factor (TCF) target genes. ER, ER, progesterone receptor, and androgen receptor mRNAs were all downregulated at 24 and/or 48 h after EE administration. Complement C3 and insulin-like growth factor 1 mRNAs were markedly induced after EE administration. Although the time courses of Wnt4, Wnt5a, and Wnt7a mRNA status varied until 12 h after EE administration, all of them were simultaneously downregulated at 24 and 48 h. The remarkable downregulation of Wnt7a mRNA in response to EE was considered to be important to understand the various uterine phenomena affected by E