This research proposal deals with the factors regulating the secretion of thyrotropin-releasing hormone (TRH) from the hypothalamus, brain and neurohypophysis of man and other mammalian species. Measurements of TRH secretion rate will be made, and the influence of physiologic stimuli, neurotransmitters, endocrine status, metabolic and psychiatric disturbances on it will be examined. The factors controlling the secretion of TRH from the hypothalamus, central nervous system, pineal, and skin of the frog will be studied using in vivo and in vitro techniques. The skin from a number of different amphibia will be screened for mammalian hypophysiotropic hormones in addition to TRH.