Final Report: Contaminant-Induced Changes in Hepatic Steroid Hormone Degradation

EPA Grant Number: R824760
Title: Contaminant-Induced Changes in Hepatic Steroid Hormone Degradation
Investigators: Guillette Jr., Louis J.
Institution: University of Florida
EPA Project Officer: Hahn, Intaek
Project Period: October 1, 1995 through September 1, 1998
Project Amount: $407,679
RFA: Human Health Risk Assessment (1995) RFA Text |  Recipients Lists
Research Category: Economics and Decision Sciences , Health Effects , Human Health , Human Health Risk Assessment , Health


To develop an understanding of contaminant-induced steroid alterations in a nonmammalian vertebrate model; in particular, to examine the role of liver degradation in this system.

Summary/Accomplishments (Outputs/Outcomes):

We have shown previously that alligators living in a Central Florida lake exhibited a number of developmental defects that persisted for the first 6 months of life. These abnormalities included alterations in plasma estrogen and androgen concentrations as well as abnormalities of the testis and ovary. We also observed that juvenile alligators (ages 3?6 years) had depressed plasma testosterone concentrations, as noted in the neonates and reduced phallus size (Guillette et al., 1996). Recent studies, supported by this grant, have observed the following:

  1. A number of contaminants identified in alligator eggs and serum exhibit an affinity for estrogen (ER) and/or progesterone (PR) receptors obtained from the alligator oviduct (Vonier et al., 1996). Current studies are examining ER from the liver. These chemicals, when added together, exhibit additivity or greater than additivity when displacing radiolabeled estradiol from the alligator ER.
  2. Abnormalities of the endocrine system in alligators are observed in other Florida wetlands that are not associated with significant pesticide spills or point source contamination, for example, Lake Okeechobee (Crain et al., 1998a; Guillette et al, accepted). Abnormalities include reduced phallus size, reduced plasma androgens, and abnormal thyroxin plasma levels.
  3. Various pesticides or pesticide metabolites (p,p'-DDD; trans-Nonachlor; dicofol) cause sex reversal in alligator embryos experimentally, demonstrating that these compounds are effective estrogens. Sex reversal?male to female?occurs at concentrations as low as 100 ppt applied to the outside of the egg. In contrast, atrazine, endosulfan, and p,p-DDE are not estrogenic in this system?do not induce male to female sex reversal?in these studies (Crain, 1997; Crain et al., 1997; Guillette et al., unpubl. data).
  4. Atrazine, however, at high doses (ppm) can induce elevated testicular expression of the steroidogenic enzyme aromatase in alligator males if exposure occurs in ovo. 2,4-D does not influence aromatase activity in alligators at the treatment doses used (Crain et al., 1997). Additionally, p,p'-DDE is an effective anti-estrogen in the alligator egg (Guillette et al., unpubl. data).
  5. Mixtures of just two pesticides or pesticide metabolites induce different endpoints than the compounds alone. For example, mixtures of p,p'-DDE and trans-Nonachlor do not induce sex reversal (male to female) as occurs with trans-Nonachlor alone. These data appear to suggest a neutralizing affect of p,p'-DDE, but animals recieving both compounds exhibit abnormalities of gonadal steroidogenesis similar to those reported for animals from Lake Apopka?a population exposed to many contaminants (Guillette et al., in prep.).
  6. Experimental evidence indicates that reduced phallus size in hatchling male alligators is associated with pesticide exposure during embryonic development. Although incubation temperature can increase variation in phallus size, reductions of the magnitude seen in the field are only observed after pesticide exposure (Rooney, Tsue, and Guillette, in prep.)
  7. Serum and cytoplasmic proteins exhibit varying affinities for EDCs and natural estrogens. We have shown that o,p-DDT and octylphenol exhibit little affinity for proteins in alligator serum (Arnold et al., 1996). Likewise, DDT and its various metabolites, endosulfan and dieldrin show little affinity for alligator uterine cytosolic proteins (Crain et al., 1998b). In contrast, toxaphene will bind to these proteins but with an affinity much reduced compared to estradiol-17b (Crain et al., 1998b).
  8. We have observed that juvenile male alligators continue to exhibit depressed plasma androgen concentrations many years after hatching (Guillette et al., 1997). Moreover, this depression in androgen is not due to stress, as males and females from Lakes Apopka and Woodruff (FL) have similar plasma corticosterone concentrations before and after a 2-hour acute stress test (Guillette et al., 1997).
  9. Alligators exhibit sexual dimorphism in hepatic degradation of testosterone, with females showing elevated enzymatic activity for oxido-reduction and hydroxylation. In contrast, alligators from Lake Apopka show no sexual dimorphism?females have been masculinized and exhibit male-like activity. No differences between sexes were observed for hepatic glucuronosylation or sulfation of testosterone (LeBlanc, McLachlan and Guillette, in prep).

Journal Articles on this Report : 13 Displayed | Download in RIS Format

Other project views: All 22 publications 17 publications in selected types All 15 journal articles
Type Citation Project Document Sources
Journal Article Crain DA, Guillette LJ, Rooney AA, Pickford DB. Alterations in steroidogenesis in alligators (Alligator mississippiensis) exposed naturally and experimentally to environmental contaminants. Environmental Health Perspectives 1997;105(5):528-533. R824760 (1998)
R824760 (Final)
not available
Journal Article Crain DA, Noriega N, Vonier PM, Arnold SF, McLachlan JA, Guillette LJ Jr. Cellular bioavailability of natural hormones and environmental contaminants as a function of serum and cytosolic binding factors. Toxicol Indus Health 1998b;14:261-273. R824760 (Final)
not available
Journal Article Crain DA, Guillette LJ Jr, Pickford DB, Percival HF, Woodward AR. Sex-steroid and thyroid hormone concentrations in juvenile alligators (Alligator mississippiensis) from contaminated and reference lakes in Florida. Environ Toxicol Chem 1998a;17:446-452. R824760 (1998)
R824760 (Final)
not available
Journal Article Crain DA, Guillette Jr LJ. Endocrine-disrupting contaminants and reproduction in vertebrate wildlife. Reviews in Toxicology 1997;1:47-70. R824760 (1998)
R824760 (Final)
not available
Journal Article Folmar LC, Denslow ND, Rao V, Chow M, Crain DA, Enblom J, Marcino J, Guillette LJ Jr. Vitellogenin induction and reduced serum testosterone concentrations in feral male carp (Cyprinus carpio) captured near a major metropolitan sewage treatment plant. Environmental Health Perspectives 1996;104:1096-1101. R824760 (Final)
not available
Journal Article Guillette Jr LJ, Crain DA, Rooney AA, Woodward AR. Effect of acute stress on plasma testosterone, estradiol-17beta and corticosterone in juvenile alligators living in control and contaminated lakes. Journal of Herpetology 1997;31:347-353. R824760 (1998)
R824760 (Final)
not available
Journal Article Guillette Jr LJ, Woodward AR, Crain AD, Masson GR, Plamer BD, Cox MC, Qui Y-X, Orlando EF. The reproductive cycle of the female American alligator (Alligator mississippiensis). General and Comparative Endocrinology 1997;108:87-101. R824760 (Final)
not available
Journal Article Guillette LJ Jr, Woodward AR, Crain DA, Pickford DB, Rooney AA, Percival HF. Plasma steroid concentrations and male phallus size in juvenile alligators from seven Florida lakes. General and Comparative Endocrinology 1999;116(3):356-372. R824760 (Final)
not available
Journal Article Guillette LJ, Brock JW, Rooney AA, Woodward AR. Serum concentrations of various environmental contaminants and their relationship to sex steroid concentrations and phallus size in juvenile American alligators. Archives of Environmental Contamination and Toxicology 1999;36(4):447-455 R824760 (Final)
not available
Journal Article Milnes MR, Bryan TA, Medina JG, Gunderson MP, Guillette Jr. LJ. Developmental alterations as a result of in ovo exposure to the pesticide metabolite p,p '-DDE in Alligator mississippiensis. General and Comparative Endocrinology 2005;144(3):257-263. R824760 (Final)
R829437 (Final)
  • Full-text: Science Direct HTML
  • Abstract: Science Direct
  • Other:
  • Journal Article Semenza JC, Tolbert PE, Rubin CH, Guillette Jr LJ, Jackson RJ. Reproductive toxins and alligator abnormalities at Lake Apopka, Florida. Environmental Health Perspectives 1997;105:1030-1032. R824760 (Final)
    not available
    Journal Article Vonier, P. M., Crain, D. A., McLachlan, J. A., Guillette, L. J., Jr., and Arnold, S. F. (1996). Interaction of environmental chemicals with the estrogen and progesterone receptors from the oviduct of the American alligator. Environ. Health Perspec. 104, 1318-1322. R824760 (1998)
    R824760 (Final)
    not available
    Journal Article Vonier, P.M., L.J. Guillette, Jr., J.A. Mclachlan And S.F. Arnold. 1997. Identification and characterization of estrogen and progesterone receptors from the oviduct of the American alligator (Alligator mississippiensis). Biochemical and Biophysical Research Communications 232: 308-312. R824760 (1998)
    R824760 (Final)
    not available

    Supplemental Keywords:

    human health, steroids, estrogen, androgen, testosterone, endocrine disruptors, progesterone receptors, estrogen receptors, pesticides, Florida, FL, reproductive toxins., RFA, Health, Scientific Discipline, Toxics, Geographic Area, Environmental Chemistry, Health Risk Assessment, pesticides, State, Endocrine Disruptors - Environmental Exposure & Risk, endocrine disruptors, Risk Assessments, Biochemistry, Children's Health, Biology, Endocrine Disruptors - Human Health, hepatic steroid, endocrine disrupting chemicals, exposure studies, hormone degradation, plasma estrogen, animal models, DDT, developmental processes, hepatic steroid hormone degradation, human exposure, dicofol, endogenous sex steroids, estrogen response, biological effects, Florida, hormone production, Lake Apopka Alligators, FL., androgen, p, p'-DDD

    Progress and Final Reports:

    Original Abstract
  • 1996
  • 1997