The effects of oral caffeine (3.3 mg/kg, equivalent to 2-3 cups of coffee) on plasma adrenocorticotropin (ACTH) and cortisol (CORT) were tested in 47 healthy young men at rest in a double-blind, placebo-controlled, crossover study. Following caffeine, ACTH was significantly elevated at all times from 30 min to 180 min, and CORT was elevated from 60 min to 120 min (Fs ≤ 8.4, ps < 0.01). Peak increases relative to placebo were: ACTH, 33% (+5.2 pg/ml) and CORT, 30% (+2.7 μg/dl) at 60 min postcaffeine. The results suggest that caffeine can activate important components of the pituitary-adrenocortical response in humans during the resting state. Caffeine's known ability to increase CORT production appears at least partly due to an increase in ACTH release at the pituitary.
Bibliographical noteFunding Information:
Supportedb y the University of OklahomaH ealth Sciences Center Honors Research Program,NIH Grant No. HL32050, and the Department of Veterans Affairs. We thank Paresh Dandona, M.D., for his stimulating discussion and thoughtful reading of the manuscript of this article. We also thank Richard B. Passey, Ph.D., Gwen A. Pin-comb, Ph.D., Bong Hee Sung, Ph.D., Barbara McKey, R.N., Judith Silverstein, MS., Jack Shepard. B.S., Henry Fry, M.S.. and Terry McDowell, Ph.D. for their efforts.