Induction of plasma interleukin-6 by circulating adrenaline in the rat.

Adrenaline, which is secreted from the adrenal medulla during stress, is considered to be involved in the control of inflammation and immune responses. Therefore, we studied the effects of adrenaline on the plasma levels of one of the major pro-inflammatory cytokines, interleukin-6 (IL-6). Here we describe that in rats, SC administration of adrenaline induces a dose-dependent increase in plasma IL-6 concentrations, reaching its maximum after 2 h. In addition, intravenous (IV) infusion of adrenaline in a dose resulting in circulating adrenaline concentrations similar to those observed during stress, enhanced heart rate and increased plasma IL-6 concentrations. The increase in plasma IL-6 in response to adrenaline given by subcutaneous (SC) route and by IV infusion could be blocked by the beta-adrenergic receptor antagonist l-propranolol but not by d-propranolol. Based on these data we conclude that under physiological conditions circulating adrenaline may be involved in the control of IL-6 production, and thereby may modulate inflammatory responses.