EXERCISE STIMULATES INTERLEUKIN-6 SECRETION - INHIBITION BY GLUCOCORTICOIDS AND CORRELATION WITH CATECHOLAMINES

In experimental animals, stress and catecholamines stimulate endogenou s interleukin-6 (IL-6) secretion, whereas glucocorticoids inhibit it. To examine whether physical stress alters the secretion of IL-6 in hum ans, and to what extent this is correlated with catecholamines and mod ified by glucocorticoids, we performed high-intensity treadmill exerci se test runs on 15 male volunteers, in a double-blind crossover design , after pretreatment with placebo, hydrocortisone, or dexamethasone. P lasma epinephrine and norepinephrine concentrations peaked 15 min afte r the start of exercise, whereas plasma IL-6 concentrations peaked twi ce, 15 min and 45 min after the onset of the test run. There was no di fference in either the epinephrine or norepinephrine peaks among the t hree treatments, but the net area under the curve for IL-6 was smaller after hydrocortisone or dexamethasone than after placebo and smaller after dexamethasone than after hydrocortisone. A positive correlation was observed between peak plasma epinephrine or norepinephrine and IL- 6 levels at 15 min. These findings suggest that IL-6 secretion is stim ulated during exercise, possibly by catecholamines, whereas exogenous glucocorticoids attenuate this effect without affecting the catecholam ine levels.