The Role of Epinephrine in the Secretion of the Adrenal Cortex *

In 1943 in a review of the factors producing adrenal cortical hypertrophy, Tepperman, Engel, and Long"1 suggested that, "The cortical hormone may inhibit the adrenotropic activity of the anterior lobe, and the adrenotropic secretion may therefore increase if the cortical hormone concentration in the body fluids falls. A fall in the cortical hormone concentration may be brought about by an increase in the rate of inactivation ('utilization') of the hormone." This suggestion was prompted by the observation of Ingle, Higgins, and Kendall'2 that the administration of cortical hormone to normal rats was followed by atrophy of their adrenal cortices, and that simultaneous administration of adrenotrophic hormone (ACTH) prevented such atrophy. The rapid inhibition of ACTH release by the administration of cortical hormone to normal animals has been adequately demonstrated by Sayers and Sayers.' These authors have shown that the depletion of the adrenal ascorbic acid which normally follows exposure of animals to a variety of conditions and agents, and which is initiated by ACTH discharge, does not occur if adrenal cortical steroids are injected prior to the imposition of the previously effective agent. In consequence they put forward a view almost identical with that expressed above, i.e., that a wide variety of circumstances and agents increase the rate of utilization of cortical hormone by the cells of the tissues. This soon leads to a reduction in the blood level of cortical hormone which acts as an effective stimulus to the release of ACTH, thus assuring a continued high level of adrenal cortical secretion. Conversely, any situation in which the blood level of cortical hormone rises to above normal levels brings about an inhibition of ACTH secretion, thus lessening the secretory rate of the adrenal cortex. In this way continued high and possibly deleterious blood levels of cortical hormone are prevented. In 1945, Long and Fry"5 and, later, Long"" pointed out that many of the circumstances associated with the release of ACTH are those which