Effects of 17β-estradiol on estrogen receptor α and β mRNA expression in tissues of the olive flounder (Paralichthys olivaceus)

This study examined the effects of an injection of 17 beta-estradiol (E-2) on the expression of estrogen receptor (ER) alpha and beta subtypes in the olive flounder (Paralichthys olivaceus). Time- and dose-related effects of E-2 on ER alpha and ER beta mRNA expression were determined by RT-PCR. In the liver of males, the two ER transcripts were up-regulated at 24 h. In the liver of females, ER alpha and ER beta were up-regulated at 36 h with the highest dose. After E-2 treatment, increases in ER alpha and ER beta expression were observed in the testis and ovary at 36 h; RT-PCR analysis showed that this increase was dose-dependent. After E-2 treatment, the brain tissue of males showed lower levels of ER alpha and ER beta compared with the untreated control group, whereas the brain tissue of females showed no significant difference compared with controls. The results confirm the hypothesis that ER regulation is tissue-specific and may be involved in E-2-mediated regulation of reproduction in the olive flounder.