CORTICOTROPIN RELEASE INHIBITING FACTOR IS ENCODED WITHIN PREPRO-TRH

Corticotropin synthesis and secretion is under negative feedback regul ation by glucocorticoids. In addition a hypothalamic factor inhibiting ACTH synthesis and secretion, named corticotropin release inhibiting factor (CRIF), has been postulated but not identified. Here we report that transient transfection of a rat prepro-TRH cDNA into the mouse an terior pituitary tumor cell line AtT-20 inhibits the synthesis and sec retion of both basal and CRH-stimulated ACTH. Thus, CRTF appears to be encoded by the same precursor as TRH, suggesting a coordinated regula tion of pituitary-adrenal and pituitary-thyroid functions.