内分泌撹乱物質と生殖機能 : 第10回公開シンポジウム : 内分泌撹乱物質の作用機序と後世代影響 : 環境変異原研究との接点

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Endocrine disruptors are resistant to degradation and are ubiquitous environmental pollutants that become concentrated in animal tissues, climb the food chain, accumulate in adipose tissue and are excreted in breast milk in large amounts. Examination of human follicular fluid revealed the presence of polychlorinated dibenzodioxins (PCDDs) and dibenzofurans (PCDFs) at concen-trations of approximately I pg/ml (0.01 pg TEQ/ml) . To study their possible action, two-cell mouse embryos were cultured in the presence of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) , the most toxic congener, at concentrations between 0.5 and 100 pM and evaluated at 24-h intervals for their development to the eight-cell and blastocyst stages. TCDD at 1, 2, and 5 pM significantly reduced the percentage of embryos reaching the eight-cell stage. However, blastocyst formation of the surviving eight-cell embryos was accelerated, with the number of cells in the blastocysts increased in a dose-dependent manner. Findings suggest that PCDDS and PCDFS may be present in human reproductive fluid and may exert some stage-specific effects on early embryonic development. Recent limited evidence has suggested a link between TCDD exposure and en-dometriosis. We examined the presence of messenger RNAS of AhR, Arnt, CYPIBI and p62 (dok) in the endometrium and compared their amounts in cases of endometriosis versus nonen-domtriosis in order to gain insight into the possible involvement of TCDD in the pathogenesis of endometriosis, using semi-quantitative reverse transcription-polymerase chain reaction analysis (RT-PCR) . The expression of AhR and dioxin-related genes in the endometrium did not differ in women with or without endometriosis which does not provide clear cut evidence for a role of TCDD in the pathogenesis of endometriosis. In addition, we found that breast feeding does not seem to increase the potential for developing endometriosis which suggests that any dioxin that may be introduced into the body through breast feeding does not harm, at least in the en-dometrium. However, the amount of pollutants in food and milk should be closely monitored and the release or dumping of dioxin-containing waste should be minimized as much as possible. (This paper, chaired by Kazuo Fujikawa, was presented to the 10th JEMS Annual Symposium, "Endocrine Disruptor Mechanism and Posterity Effects-Concern with Environmental Mutagen Research", organized by Kiyomi Kikukawa, Tohru Shibuya, and Kazuo Fujikawa, sponsored by the Environmental Mutagen Society of Japan, and held at The Pharmaceutical Society of Japan, Nagai Memorial Hall, May 28, 1999.)
日本環境変異原学会の論文
1999-10-29

内分泌撹乱物質と生殖機能 : 第10回公開シンポジウム : 内分泌撹乱物質の作用機序と後世代影響 : 環境変異原研究との接点

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