Thyroid Hormone Disruption and Reproduction
Several classes of environmental contaminants have been identified as having the ability to alter thyroid hormone signaling. Though thyroid hormones are most well recognized for their roles in regulating somatic growth and development, they also have roles in a variety of other physiological processes. Our lab is particularly interested in the impacts of thyroid disruption on reproduction as there is evidence of crosstalk between the endocrine axes that regulate thyroid and sex steroid hormones. Thus, we have completed several experiments aimed at uncovering the impacts of adult and early life stage (ELS) thyroid disruption on reproduction. Our results show that early life stage thyroid disruption leads to significant reductions in the fecundity of fathead minnows (a common model organism in endocrine disruption screening). Interestingly, these reductions in fecundity are related to the exposure history of male fish, rather than female fish suggesting that ELS thyroid disruption impacts key aspects of male reproduction. In an effort to explain these results, subsequent transcriptomic and behavioral studies were conducted to determine whether ELS thyroid disruption modifies neurological development and alters male reproductive behavior. The results of these studies provided evidence that ELS thyroid disruption alters the expression of key genes and pathways associated with neuronal developmental and the intra- and interspecific sexual behaviors of males. Collectively, the results of these studies inform the development of adverse outcome pathways that link molecular level changes to whole-organism impacts as illustrated in the image below. Publications detailing this work are currently being drafted - stay tuned for more!