This project will take advantage of unique aspects of the hypothalamic-pituitary system in a common species of turtle (Pseudemys scripta) and frog (Rana pipiens) to study the dynamic relationship between brain peptide regulation of pituitary function and its modulation by peripheral feedback in relation to gonadal and thyroidal function. The turtle pituitary model will be used to study responsiveness of TSH secretion and environmental regulation of TSH secretion with emphasis on plasma binding proteins. Thyroxine binding protein will be purified and characterized for studies on its physiological role in the regulation of thyroid hormone transport and function in hopes of developing a model for understanding the evolution and function of thyroxine binding globulins. The demonstrated resistance of the frog pituitary to desensitization by gonadotropin-releasing hormone (GnRH) will be exploited to study the action of this neuropeptide on gonadotropin biosynthesis and its modulation by steroids. Parallel measurements of GnFH in the hypothalamus willl seek to determine how steroids influence pituitary regulation by actions in the brain.//
