Grantee Research Project Results

Interactions between thyroid and corticosteroid systems during the early life history of an estuarine dependent fish: A possible target for endocrine disruption by atrazine

EPA Grant Number: F5D10695
Title: Interactions between thyroid and corticosteroid systems during the early life history of an estuarine dependent fish: A possible target for endocrine disruption by atrazine
Investigators: Applebaum, Scott
Institution: The University of Texas at Austin
EPA Project Officer: Packard, Benjamin H
Project Period: August 31, 2005 through June 1, 2008
Project Amount: $111,000
RFA: STAR Graduate Fellowships (2005) RFA Text | Recipients Lists
Research Category: Academic Fellowships

Objective:

Thyroid and corticosteroid hormones have important roles in regulating the development of marine fish from embryonic period to the larval phase, and on to juvenile. The thyroid and corticosteroid systems may interact with synergistic, antagonistic, or co-regulatory effects on their respective actions. Alterations of these actions by anthropogenic compounds such as herbicides may impact development and have implications for health and survival of individual fish and fish populations in the wild. This project will address the hypotheses that a) the thyroid and corticosteroid systems interact to influence growth and development during the early life history of red drum (Sciaenops ocellatus), b) the nature of this interaction changes during ontogeny and c) environmentally relevant concentrations of atrazine alter expression of thyroid and corticosteroid hormone receptors, thereby influencing endocrine action during the early life history of red drum.

Approach:

A series of experiments using laboratory reared larvae will:

Determine the pattern of TRα, TRß and GR mRNA expression during larval development of red drum using quantitative polymerase chain reaction.
Use pharmacological inhibitors of hormone production and action, to determine the nature (stimulatory, inhibitory) and intensity of interactions between the thyroid and corticosteroid systems during distinct portions of larval development as indicated by changes in gene expression, hormone concentration, growth and development.
Assess the possible effect of atrazine exposure on thyroid or corticosteroid systems which may alter the normal patterns of interaction of these systems, resulting in changes in gene expression, growth or development.

Expected Results:

This research will determine whether interactions between the thyroid and corticosteroid systems are consistent throughout the early life history of marine fish, or whether such interactions vary during development. This study will indicate whether endocrine related gene expression may be altered by atrazine exposure at concentrations observed in estuarine habitat.

Supplemental Keywords:

atrazine, cortisol, endocrine disruption, metamorphosis, nuclear receptors, ontogeny, red drum, Sciaenops ocellatus, thyroxine, triiodothyronine,, RFA, Health, Scientific Discipline, Toxics, Environmental Chemistry, Endocrine Disruptors - Environmental Exposure & Risk, pesticides, endocrine disruptors, Biochemistry, Endocrine Disruptors - Human Health, Biology, bioindicator, altered gene expression, biomarkers, fish, EDCs, endocrine disrupting chemicals, developmental biology, animal models, corticosteroid, atrazine

Progress and Final Reports:

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.