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TIME-DEPENDENT EFFECTS ON GENE EXPRESSION IN RAT SEMINAL VESICLE DEVELOPMENTALLY ALTERED BY IN UTERO EXPOSURE TO TCDD
Citation:
Richardson, V. M., J. T. Hamm, AND L S. Birnbaum. TIME-DEPENDENT EFFECTS ON GENE EXPRESSION IN RAT SEMINAL VESICLE DEVELOPMENTALLY ALTERED BY IN UTERO EXPOSURE TO TCDD. Presented at SOT, San Francisco, CA, March 25 - 29, 2001.
Description:
TIME-DEPENDENT EFFECTS ON GENE EXPRESSION IN RAT SEMINAL VESICLE DEVELOPMENTALLY ALTERED BY IN UTERO EXPOSURE TO TCDD. V M Richardson', J T Hamm2, and L S Birnbaum1. 'USEPA, ORD/NHEERL/ETD, Research Triangle Park, NC, USA, 'Curriculum in Toxicology, University of North Carolina, Chapel Hill, NC, USA.
A gestational exposure to 2,3.7.8-tetrachlorodibenzo-p-dioxin (TCDD) has been shown to alter male reproductive development in rats (Mably et al., 1992a; Gray et al., 1995). In utero and lactational exposure to TCDD resulted in alterations in the budding of the fetal prostate as well as postnatal epithelial differentiation and smooth muscle thickness (Roman et al., 1998). In postnatal day (PND) 32 rat pups, TCDD-induced decreases in seminal vesicle weight appear to result from altered epithelial development (Harnm et al., 2000). This study examines the effects of TCDD on the expression of Ah receptor, Arnt and CYPIAI in exposed rat pups using real-time PCR. Time-pregnant Long Evans rats were treated orally with 1.0 ug TCDD /kg of body weight on gestational day 15. Male pups were sacrificed on PNDs 4, 10, 25, and 32 and whole body and paired seminal vesicle weights were recorded. Tissues were collected and stored at -80?C until analyzed. Seminal vesicle weights were not significantly different between control and exposed animals at PNDs 4,10, and 25, but by PND 32 exposed animals had lower seminal vesicle weights (59.6? 11.1 versus 36.7? 9.4 rng) in comparison to control animals. A time-dependent increase in TCDD-induced CYPIAI mRNA expression reached a maximum at PND 10 in seminal vesicle as compared to controls followed by a time-dependent decrease. While there were no significant differences in AhR and Arnt mRNA expression between control and treated animals, a slight decrease at PND 32 was observed in Ahr and Arnt mRNA expression for both control and TCDD exposed seminal vesicles. This study demonstrates that in utero and lactational exposures to TCDD results in an induction in cytochrome P450 IAI and a significant decrease in seminal vesicle weights while not effecting the pattern of AhR and Arnt expression. (This is an abstract of a proposed presentation and does not necessarily reflect EPA policy).