Several recent reports indicate that exercise elevates the plasma interleukin 6 levels; however, the precise regulation of such an elevation still remains to be clarified. In this study, in order to clarify the requirements of central and peripheral catecholaminergic system for this exercise-induced interleukin 6 elevation, rats were either intraperitoneally or intracerebroventricularly injected with 6-hydroxydopamine which depletes the catecholamine in the central or peripheral tissues. As a result, our exercise protocol elevated the plasma interleukin 6, ACTH, and corticosterone levels in response to exercise. All such exercise-induced increases in the interleukin 6, ACTH, and corticosterone levels were significantly inhibited by pretreatment with an intracerebroventricular injection of 6-hydroxydopamine. In the intraperitoneal 6-hydroxydopamine-treated animals, the exercise-induced interleukin 6 elevation was significantly suppressed compared with the vehicle-treated animals, although no significant difference was found in either the ACTH level or the corticosterone level between both groups of animals. These results thus suggest that central and peripheral catecholamines are involved in the regulation of the exercise-induced interleukin 6 elevation.