Cytochemical bioassays of polypeptide hormones

Abstract

Introduction In the early days of endocrinology hormones were recognized, and assayed, by some characteristic biological function. For example, corticotrophin (ACTH) was assayed by the amount of corticosterone which was produced in vivo as a response to the injection of graded amounts of this hormone into rats (Lipscomb & Nelson, 1962). This was a simple and direct effect of ACTH. Equally, it could be assayed by the depletion in vivo of ascorbate from the adrenal gland (Sayers, Sayers & Woodbury, 1948). Although there was a clear correlation between the loss of ascorbate from the adrenal and the concentration of ACTH acting on the gland, there was little information relating ascorbate depletion and secretion of corticosterone or cortisol (depending on the animal used in the assay). The obvious physiological effect of ACTH was to produce corticosterone (or cortisol), but the hormone could be assayed with reasonable precision by a secondary, or biochemical, phenomenon which is now recognized as being part of the biochemical mechanisms involved in steroidogenesis (Chayen, Daly, Loveridge & Bitensky, 1976).