2002 Progress Report: Effects of an Endocrine Disruptor on Prostate Development and GrowthEPA Grant Number: R827403
Title: Effects of an Endocrine Disruptor on Prostate Development and Growth
Investigators: Timms, Barry G.
Institution: University of South Dakota
EPA Project Officer: Hahn, Intaek
Project Period: July 1, 1999 through June 30, 2002
Project Period Covered by this Report: July 1, 2001 through June 30, 2002
Project Amount: $432,452
RFA: Endocrine Disruptors (1999) RFA Text | Recipients Lists
Research Category: Economics and Decision Sciences , Endocrine Disruptors , Health , Safer Chemicals
The overall objective of this research project is to determine the consequences of exposure to endocrine disruptors during fetal prostate development, particularly environmental estrogens. The goal of the study is to understand the mechanisms associated with our initial finding of dose-dependent effects on prostate growth as a result of fetal exposure to environmental chemicals. The specific objective of this research project is to examine regional growth effects in the urogenital sinus (UGS) following exposure of mouse fetuses to a low, physiologically relevant dose of the pesticide, methoxychlor (MXC). By comparison, the effects of a high dose of MXC will be examined and compared to diethylstilbestrol (DES) treatment as a positive control.
The initial 6-month period of the project was used to prepare the laboratory environment for the program of study, establish protocols, and hire personnel.
The plan for Year 1 of the project was to study the effects of prenatal exposure to environmental estrogens on ductal budding patterns and morphometry in the developing prostate of male mice. Control and DES positive control-treated groups have been analyzed, and the preliminary findings are summarized below.
Pregnant female CD-1 mice were fed oil (control) or oil plus DES (0.1 µg/kg) on gestation days 14-18. Caesarian delivery was performed on day 19. To preclude intrauterine position effects, one male per litter was used for the studies. A total of five animals were taken for each group. The urogenital complex was fixed in situ according to previously published protocols. Serial sections were prepared on coded samples. Morphometric analysis was performed to provide data on the number of buds and three-dimensional reconstruction for the control and positive control (DES)-treated animals (see Figure 1).
Using Reconstruction Image Data, the Budding Pattern Differences Are Observed Clearly, and the Low Dose Effects of a Positive Estrogen Control (DES) Suggest Growth Increases in the Dorsolateral and Ventral Regions of the Prostate (see Figure 2).
A. Surface-Rendered Reconstruction of Control, 19-Day Male Fetus (One Male - Dorsolateral View).
B. Surface-Rendered Reconstruction of DES-Treated (0.1 µg/kg), 19-day Male Fetus (One Male - Dorsolateral View). Urethra (red), dorsocranial gland (dark blue), dorsal prostate (green), lateral prostate (yellow), and ventral prostate (pale blue).
Although the budding data have not typically shown highly significant differences, our experience with another positive control (ethinyl estradiol) and an endocrine disruptor (bisphenol A) indicate that the mean cross-sectional area measurement (an indicator of volume) is correlated with a more significant growth effect (vom Saal, et al., 2000; Kaiser, 2000).
The reconstruction data for the high-dose DES-positive control indicate that this dose range results in abnormal UGS development in some animals. In these instances, where portions of the Müllerian system are retained, there is an inhibition of dorsal prostate budding, although lateral and ventral buds are observed. In all cases examined thus far, the effects of higher physiological doses of estrogen result in an overall decrease in the number of prostatic outgrowths, except for the ventral region.
The preliminary data suggest that these morphological growth parameters should provide useful information about prostate development when we examine the effects of MXC treatment during fetal development. Based on published and current preliminary data, it is postulated that low, physiologically relevant disruption (i.e., endocrine disruption) during critical periods of reproductive development in the male fetus will likely cause alterations of growth parameters.
Kaiser J. Endocrine disrupters: panel cautiously confirms low-dose effects. Science 2000;290:695-697.
We plan to complete the fetal treatment groups for the reconstruction analyses during the subsequent grant period. Additional animals will be treated and examined after puberty and maturation to study the long-term consequences on prostate growth and development of fetal exposure to endocrine disrupters.
Supplemental Keywords: health effects, dose-response, mammalian, cellular, chemicals, histology, prostate development, methoxychlor, MXC, urogenital sinus, UGS, diethylstilbestrol, DES, morphometric analysis, fetal prostate development, dose-dependent effects, pesticides, endocrine disruption, morphological growth parameters.