CENTRAL OPIATE MODULATION OF PERIPHERAL IL-6 IN RATS

THE effect of opiate agonists and antagonists on the induction of seru m interleukin-6 (IL-6), an inflammatory cytokine that plays a major ro le in the acute phase response, was studied. Morphine (10 mu g, i.c.v. or 15 mg kg(-1), i.p.), beta-endorphin (0.5 or 5 mu g, i.c.v.) and et orphin (10 mg kg(-1), i.p.) induced IL-6. Moreover, morphine potentiat ed the IL-6 response induced by IL-1 beta (400 ng, i.p. or i.c.v.). Wh en injected intraperitoneally, the opiate antagonist naloxone hydrochl oride, antagonized the IL-6 response induced by either i.c.v. or i.p. IL-1 beta. This effect was not seen with naloxone methiodide, which do es not cross the blood-brain barrier. The data show that central opiat es are effective modulators of the inflammatory cytokine IL-6.