Androgen rather than estrogen up-regulates brain-type cytochrome P450 aromatase (cyp19a1b) gene via tissue-specific promoters in the hermaphrodite teleost ricefield eel Monopterus albus

► The expression of cyp19a1b in the hypothalamus and pituitary of ricefield eel is not responsive to estrogens. ► The expression of cyp19a1b of ricefield eel in the pituitary is up-regulated by androgens. ► The expression of cyp19a1b in the brain and pituitary of ricefield eel is driven by alternative tissue-specific promoters. ► The brain-specific promoter of cyp19a1b contains a non-consensus ERE, thus does not respond to estrogen stimulation. ► The pituitary-specific promoter of cyp19a1b contains an ARE, which mediates the up-regulation by androgens.