PARENT SESSION
FEMALE REPRODUCTIVE TRACT - B

Wednesday, August 4, 2004
10:30 AM–12:30 PM
Buchanan Courtyard

(822) EXPOSURE TO BISPHENOL A DURING LATE PREGNANCY RESULTED IN AN INCREASE OF CALBINDIN-D9K mRNA AND PROTEIN IN MATERNAL AND POSTNATAL RAT UTERI.

Hong, Eui-Ju ¹, Choi, Kyung-Chul ², Leung, Peter C. K. ², Jeung, Eui-Bae^{1, 3}, ¹ Laboratory of Veterinary Biochemistry and Molecular Biology, Cheongju, Republic of Korea² Department of Obstetrics and Gynecology, University of British Columbia, Vancouver, BC, Canada³ Xenotransplantation Research Center, Seoul, Rebublic of Korea

ABSTRACT- The expression level of CaBP-9k mRNA is rapidly and strongly induced by environmental estrogenic compounds, possibly through a classical pathway of estrogen receptor (ERalpha), in which can be evaluated as an early gene marker for assaying an estrogenic effect of putative environmental chemicals in rat uterus. Based on the previous results, the present study was further performed to investigate the expression levels of CaBP-9k mRNA and protein in postnatal rat uterus following maternal exposures to diethylstilbestrol (DES), 17beta-estradiol (E2) and bisphenol A (BPA) during neonatal period. Thus, we investigated the effect of BPA on the expression levels of CaBP-9k mRNA and protein in the maternal and postnatal uterus on day 5 of delivery. Treatment with a high dose of BPA (600 mg/kg body weight (BW) per day) resulted in an increase of CaBP-9k mRNA (3-fold) for 3 days, and a single dose of DES (50 ug/kg BW) and E2 (40 ug/kg BW) induced an increase of CaBP-9k mRNA (5-fold and 2-fold, respectively) in maternal uterus. In parallel with maternal expression of CaBP-9k mRNA, the expression level of CaBP-9k mRNA was significantly increased when treated with BPA (4-fold, 600 mg/kg BW per day) and DES (41-fold, 50 ug/kg BW per day) in postnatal uterus. Treatment with increasing concentrations of BPA and a single dose of DES resulted in a significant increase in the expression level of CaBP-9k protein in maternal uterus. In addition, increasing doses of BPA and a single dose of DES induced a significant increase of ERalpha mRNA in postnatal uterus. In addition, treatment with BPA resulted in the induction of CaBP-9k protein in maternal uterus by immunohistochemistry. In summary, we demonstrated that maternal exposure to BPA during late pregnancy induced the expression levels of CaBP-9k mRNA and protein in maternal and postnatal uteri. These results suggest that the absorption and distribution of environmental estrogenic compounds in maternal and neonatal uteri are extremely rapid and these chemicals can easily pass though placenta during pregnancy to affect postnatal reproductive tissues. [This work was supported by Korea Research Foundation Grant (KRF 2002-041- E00238)].

KEY WORDS: Calbindin-D9k, Endocrine disruptor, Uterus, Rat