Meeting Abstract

S1-2.2  Thursday, Jan. 3  The Thyroid-Gonad axis: Insights on a novel mechanism of communication in the American Alligator BERMUDEZ, DS*; GUILLETTE, LJ; University of Florida dieldrich@gmail.com

Thyroid hormones are known to have a cooperative role in gonadal development and function. There is a growing body of work demonstrating that thyroid hormones play a crucial role in the development of Sertoli and Leydig cells in the testis. Thyroid hormones at proper levels are necessary for ovulation and severe hypothyroidism can cause ovarian atrophy and amenorrhea. Thyroid receptors are found in various parts of the ovary such as granulosa cells, oocytes and cumulus cells of the follicle, and corpora lutea, indicating that thyroid hormones can play a role in various cells of the ovary. The mechanisms of action are still not well understood. In many vertebrate species, including humans, thyroid disorders are more frequent in the female population. In addition, studies have shown that neoplastic thyroids have a higher number of estrogen receptors (ER) compared to normal tissue, suggesting a relationship between the sex of an individual and susceptibility to thyroid abnormalities. Recently, it has been shown that thyroid hormone concentrations parallel sex steroid patterns in American alligators. We investigated the mechanism of communication between the thyroid and gonad axis of the American alligator. Previous studies have demonstrated a one directional endocrine pathway from the thyroid to the gonad. We describe a possible new avenue of communication from the gonad to thyroid via the estrogen receptor located on alligator thyroid follicles. Through the use of genetic markers for thyroid and gonadal physiology, we describe a novel mechanism of communication between these organs.