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The Hypothalamic-Pituitary-Thyroid (HPT) Axis in Frogs and its Role in Frog Development and Reproduction
Citation:
FORT, D. J., S. J. DEGITZ, J. E. TIETGE, AND L. TOUART. The Hypothalamic-Pituitary-Thyroid (HPT) Axis in Frogs and its Role in Frog Development and Reproduction. CRITICAL REVIEWS IN TOXICOLOGY. CRC Press LLC, Boca Raton, FL, 37(1-2):117-161, (2007).
Impact/Purpose:
We provide an in-depth review of the amphibian thyroid system with particular focus on the role that TH plays in metamorphosis. We review the amphibian hypothalamic-pituitary-thyroid (HPT) axis, focusing on thyroid hormone synthesis, transport, and metabolism.
Description:
Metamorphosis of the amphibian tadpole is a thyroid hormone (TH)-dependent developmental process. For this reason, the tadpole is considered to be an ideal bioassay system to identify disruption of thyroid function by environmental contaminants. Here we provide an in-depth review of the amphibian thyroid system with particular focus on the role that TH plays in metamorphosis. We review the amphibian hypothalamic-pituitary-thyroid (HPT) axis, focusing on thyroid hormone synthesis, transport, and metabolism. We also discuss the molecular mechanisms of TH action, including the role of TH receptors, the actions of TH on organogenesis, and the mechanisms that underlie the pleiotropic actions of THs. Finally, we discuss methods for evaluating thyroid disruption in frogs, including potential sites of action, relevant endpoints, candidate protocols for measuring thyroid axis disruption, and current gaps in our knowledge.
