This Article Full Text (PDF) Submit a related Letter to the Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints, Permissions and Rights Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by CERESA, F. Articles by MOLINO, G. Search for Related Content PubMed PubMed Citation Articles by CERESA, F. Articles by MOLINO, G.

Once-a-Day Neurally Stimulated and Basal ACTH Secretion Phases in Man and Their Response to Corticoid Inhibition

Istltuto di Semeiotica Medica dell'Università di Torino, Strada S.Vito 34 10133 Torino, Italy

The sensitivity of the ACTHsecreting system to corticoid inhibition was studied in normal subjects by measuring variations in excretion of urinary 17-OHCS induced by intravenous infusion of corticoids in different periods of the day (4–8 AM; 4 AM–4 PM; 8 AM–4 PM; 4–8 PM; 8 PM–midnight; midnight–4 AM). Submaximal infusion doses (660 µg/hr 6-methylprednisolone; 30 µg/hr dexamethasone) led to partial inhibition only in the nocturnal early morning hours and no inhibition in the period from 8 AM to midnight; only massive doses of dexamethasone (200 µg/hr) produced inhibition in this latter period. The following hypothesis is put forward: The ACTH-secreting system has 2 daily activity phases with different control mechanisms. One in the nocturnal early morning hours is the result of neural activity directed to the hypothalamus, superimposed on the basal activity and responsible for the circadian rhythm. This once-a-day impulse would appear to be linked to the rapid eye movement sleep stages. Corticoid-induced inhibition in submaximal doses is possible only during this phase. The second phase is characterized by a steady basal activity lasting 24 hr. It is independent of the early morning hour impulse and is resistant to all but massive doses of corticoids.

Received November 22, 1968.

This article has been cited by other articles:

				R. J. Martin, S. J. Szefler, V. M. Chinchilli, M. Kraft, M. Dolovich, H. A. Boushey, R. M. Cherniack, T. J. Craig, J. M. Drazen, J. K. Fagan, et al. Systemic Effect Comparisons of Six Inhaled Corticosteroid Preparations Am. J. Respir. Crit. Care Med., May 15, 2002; 165(10): 1377 - 1383. [Abstract] [Full Text] [PDF]

				B. T. Walsh, E. S. Lo, T. Cooper, D. C. Lindy, S. P. Roose, M. Gladis, and A. H. Glassman Dexamethasone Suppression Test and Plasma Dexamethasone Levels in Bulimia Arch Gen Psychiatry, September 1, 1987; 44(9): 797 - 800. [Abstract] [PDF]