|Budget Amount *help
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2002: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2001: ¥2,100,000 (Direct Cost: ¥2,100,000)
In this study, we introduced estrogen and bisphenol as an endocrine disruptor and vitamin A as an inhibitor of the effect of such endocrine disrupters on the developing reproductive system in female and male mice. The results also suggested that, to a certain extent, the replenishment of vitamin A-rich food is important for relieving the effect of endocrine disruption in babies, caused by exogenous estrogenic substances, since the effect of such substances on the developing reproductive tracts should exert via vitamin A deficiency. On the other hand, unusual mRNA expression of a cellular retinol binding protein 2, which regulates the metabolism of vitamin A, was found in the reproductive tracts after neonatal exposure to estrogen. Therefore, it could be proposed that the neonatal effects of both estrogen and bisphenol A on the vaginal differentiation and spermatogenesis are exerts through the suppression of vitamin A action. Although the interaction of vitamin A with estrogenic substances during a critical period was not clarified, a possible explanation is conceivable : 1) at first, neonatal treatment with estrogenic substances leads to the disruption of vitamin A metabolism and/or transportation in the reproductive tracts ; 2) the direction of normal differentiation of the reproductive tracts is changed by a lack of appropriate vitamin A action ; 3) the reproductive tracts, of which the direction of normal differentiation is changed, receive the continuing estrogenic stimulation as a proliferation signal ; and 4) the reproductive tracts differentiate to an abnormal direction.