NOGUCHI Junko National Institute of Agrobiological Resources, Devision of Agrobiological Resources II, Scientist, 農業生物資源研究所, 研究員
SHIROTA Mariko Hatano Research Institute, Food and Drug Safety Center, Scientist, 秦野研究所, 研究員
|Budget Amount *help
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2000: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1999: ¥2,000,000 (Direct Cost: ¥2,000,000)
The present study investigated the effects of a xenobiotic estrogen, Bisphenol A(BPA)and Octylphenol(OP)on reproductive functions using male and female rats. Results indicated that BPA and OP directly inhibit testicular functions. The testis is probably a more sensitive site for BPA and OP actions than the hypothalamus-pituitary axis. On the other hand, the exposure of neonatal female rats to higher doses of OP disrupts the cyclic release of LH, FSH and prolactin, and interferes with the display of sexual receptive behavior in adulthood.
The Hatano high- and low-avoidance animals(HAAs and LAAs), selectively bred from Sprague-Dawley rats, are characterized as an intra-strain dissociation in avoidance learning, locomotor activity, puberty, estrous cycles, sperm motility, hypothalamo-pituitary-adrenal(HPA)axis and immune response. The present study was therefore designed to compare the effects of lactational exposure to genistein, a phytoestrogen, on those functions between HAAs and LAAs.
To this aim, litters from both strains were fostered onto Sprague-Dawley rats, which were administered from gestational day 17 to postnatal day 21. In LAAs, puberty was significantly delayed in the both sexes of offspring reared by genistein-treated dams compared with those by vehicle-treated dams, whereas no significant effects of genistein on puberty were observed in HAAs. Open field activity was significantly increased in male HAAs that reared by genistein-treated dams. The number of lymphocytes and antibody production response to sheep red blood cells were significantly decreased in HAAs reared by genistein-treated dams. No genistein-related but strain-related differences were detected in estrous cycling, learning behavior, sperm motility and weight of reproductive organs. These results demonstrated that genistein has endocrine disrupting effects on behavior, reproduction and immune response of rats when exposures during lactation. These results also indicated that there are clear differences of endocrine disrupting effects in two genetically selected strain rats. Less