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POSTNATAL DISPOSITION OF TCDD IN LONG EVANS RATS FOLLOWING GESTATIONAL EXPOSURE
Citation:
Diliberto, J J., F. McQuaid, J. T. Hamm, AND L S. Birnbaum. POSTNATAL DISPOSITION OF TCDD IN LONG EVANS RATS FOLLOWING GESTATIONAL EXPOSURE. Presented at SOT, San Francisco, CA, March 25 - 29, 2001.
Description:
POSTNATAL DISPOSITION OF TCDD IN LONG EVANS RATS FOLLOWING GESTATIONAL EXPOSURE.
J J Diliberto', J T Hamm'.2, F McQuaid', and L S Birnbaum'. 'US EPA, ORD/NHEERL/ETD, RTP, NC; 2Curriculum in Toxicology, University of North Carolina, Chapel Hill, NC.
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) causes a wide range of adverse effects including alterations in reproductive development. In utero and lactational exposure to TCDD in rats have demonstrated perturbations in male sex accessory glands, female genitalia, and the immunue system. Previous studies have shown association of tissue concentrations and incidence of certain reproductive/developmental alterations in embryo/fetal tissues. The objective of the present study was to determine postnatal TCDD disposition in pups after in utero and lactational exposure. Pregnant Long Evans dams were dosed po on GD 15 with 0.78 g [3H]TCDD/kg. At various postnatal days (PNDs), dams and pups were euthanized. At necropsy, tissues were collected to determine dosimetry. Also, whole male pups were collected at various PNDs for determination of total ng TCDD per pup. Maternal liver to fat (L/F) ratio on PND1 was >1; by PND7, L/F was <1. Following PND1, concentration of TCDD decreased rapidly in all maternal tissues except adipose, which remained steady until PND4 and decreased slowly thereafter. In the pups, whole body tissue concentrations peaked at --PND4 and remained relatively constant to PNDI 5 and then rapidly decreased. In contrast, total ng TCDD in pups continued to rise until weaning. Between PND15 to 25, total ng TCDD in pups showed a slight increase but the rapid rise in body wt resulted in substantial decreases in tissue concentrations. The lactational transfer appeared to be highest on PND 1 and decreased thereafter. Whole pup concentration on PND 1 was - 3 times greater than in whole fetus on GD21 in the maternal rat. Data from this study define tissue concentrations of TCDD within dam and offspring during a critical period of development and help to further establish TCDD tissue concentrations associated with developmental alterations. (This abstract does not necessarily reflect EPA policy.)