RESUMEN
Two experiments were conducted to determine effects of Juzen-taiho-to on endometrial carcinogenesis in mice. In the first experiment, Juzen-taiho-to treatment (2 weeks) decreased the levels of estradiol-17 β (E<sub>2</sub>)-stimulated expression of c-fos/jun mRNA and their oncoproteins, determined by reverse transcription-polymerase chain reaction and Southern blot analysis, and immunohistochemical method, in the uteri of ovarectomized mice. For the second experiment, 93 female ICR mice were given N-methyl-N-nitrsourea (MNU) solution (1mg/100g body wt.) and normal saline (as controls) into their left and right uterine corpora, respectively, and were divided into four groups. Group 1 was given 0.2% Juzen-taiho-to and 5 ppm E<sub>2</sub>-containing diet. Group 2 was given 5ppm E<sub>2</sub>-containing diet alone. Group 3 was exposed to 0.2% Juzen-taiho-to containing diet alone. Group 4 was kept on the basal diet alone and treated as a control. Juzen-taiho-to treatment significantly decreased incidences of the uterine endometrial atypical (P<0.01), complex (P<0.05) and simple hyperplasias (P<0.01), under estrogenic stimulation. It is suggested that Juzen-taiho-to has an inhibitory effect on E<sub>2</sub>-related endometrial carcinogenesis in mice, relevantly through suppression of estrogeninduced c-fos/jun-expression.