LAUSR

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), commonly referred to simply as "dioxin", is a persistent environmental pollutant. Because of its high environmental persistence and biological accumulation, humans and animals are often exposed to TCDD. Therefore, the harmful effects on humans and animals is a major concern. Although studies have elucidated the adverse estrogenic and anti-estrogenic effects of TCDD, it is unclear in which tissues TCDD exerts these effects in vivo. To investigate the estrogen-related effects of TCDD in various tissues, we generated an improved estrogen-responsive reporter transgenic mouse in which the luciferase gene luc2 is expressed in response to estrogenic signals. Using these mice, we clarified that TCDD inhibits estrogenic signaling in liver and kidney but enhances estrogenic signaling in the pituitary gland in the same individual. Expression of aryl hydrocarbon receptor, aryl hydrocarbon receptor nuclear translocator, and estrogen receptor alpha mRNA was detected in liver, kidney, and pituitary gland, suggesting that the effects of TCDD on estrogenic signaling in these organs is independent of the expression pattern of these receptors. Thus, our results indicate that TCDD exerts both estrogenic and anti-estrogenic tissue-specific effects within the same individual.