Influence of the hormonal forms of ACTH on the pattern of corticosteroid secretion

In the pituitaries of man, monkey, sheep, dog, cat and guinea pig the predominant component of immunoreactive ACTH has a molecular size resembling the usual 1–39 peptide (little ACTH). Cortisol is the predominant glucocorticoid in these species. Rabbit, rat and mouse pituitaries contain a newly described intermediate sized ACTH and corticosterone as their principal glucocorticoid. Bovine pituitaries contain intermediate and little ACTH in about equal amounts and their cortisol: corticosterone ratio is about 1. These findings are consistent with our hypothesis that the hormonal form of ACTH is an important factor regulating the cortisol: corticosterone ratio in mammalian adrenal corticoid secretion.