Localisation of gonadotropin-releasing and thyrotropin-releasing hormones in human brain by radioimmunoassay

GONADOTROPIN-RELEASING hormone (GnRH) and thyrotropin-releasing hormone (TRH) are two hypothalamic oligopeptides which regulate the secretion of gonadotropins and of thyroid-stimulating hormone (TSH), respectively, from the anterior pituitary^1,2. It is generally accepted that these neurohormones are produced by nerve cells, transmitted along axons and stored in nerve endings; when released, they are transferred by way of the hypothalamo-hypophyseal portal system to the anterior pituitary³. Human brains of adults have been shown to contain GnRH and TRH activity ⁴ but quantitative measurements of these hormones are available for brains of aborted foetuses only⁵. This report deals with the distribution of GnRH and TRH in the adult human brain, their possible sites of formation, routes of migration and sites of storage in the pituitary stalk.