PARENT SESSION
PT2 - Endocrine Disruption
Tuesday, 19 November 2002
8:00 AM to 6:30 PM
Exhibit Hall
(P548) Adult Exposure to the Phytoestrogen Apigenin Results in Changes in Endocrine Parameters but Fails to Alter Fecundity.
Foran, Christy*,1, Peterson, Bethany2, Benson, William3, 1 West Virginia University, Morgantown, WV, USA2 University of Mississippi, University, MS, USA3 U. S. Environmental Protection Agency, Gulf Breeze, FL, USA
ABSTRACT- Plant-derived estrogens offer the opportunity to investigate the potential for weakly estrogenic compounds to influence endocrine function and reproduction. The presence of these phytoestrogens in foods, agricultural and industrial run-off has the potential to increase the total load of estrogen in exposed populations, and produce confounding estrogenic and anti-estrogenic effects in competition with endogenous estradiol. In order to determine how exposure to phytoestrogens would alter the relationship of biomarkers of estrogen exposure and reproductive output, we exposed adult Japanese medaka, Oryzias latipes, to apigenin at concentrations from 0 to 500 
g/L. Apigenin, a flavone found in several kinds of fruits and vegetables and used as an herbal medicine, is known to activate the estrogen receptor (beta > alpha). Apigenin did not affect the number of eggs produced by reproductively active pairs of medaka, the size of eggs produced or the rate of fertilization over the two-week exposure period. However, the percent of fertilized eggs that successfully hatched was more variable in groups treated with 1 and 500 g/L apigenin. Hepatic vitellogenin concentrations were increased in males and females with apigenin treatment at 50 g/L, but not in higher treatment groups. All apigenin treatments produced lower plasma estradiol concentrations in females, but male plasma estradiol was unaffected. These results are further evidence that the relationship between biomarkers and reproductive output will vary with the type of estrogen involved as well as the need to further investigate the mechanisms behind non-monotonic dose response curves.
Key words: reproduction, brain-pituitary-gonadal axis, Japanese medaka, estrogen