AJP - Regulatory, Integrative and Comparative Physiology, Vol 273, Issue 3 956-R959, Copyright © 1997 by American Physiological Society
Interleukin-6 is differently modulated by central opioid receptor subtypes
M. Bertolucci, C. Perego and M. G. De Simoni
Istituto di Ricerche Farmacologiche Mario Negri, Milan, Italy.
The central endogenous opioid system is involved in the modulation of
interleukin (IL)-6, an inflammatory cytokine that plays a major role in the
acute phase response. The present study evaluates whether specific opioid
receptor subtypes are selectively involved in this immunomodulatory action.
IL-1 beta was administered either intracerebroventricularly or
intraperitoneally at the dose of 400 ng to rats pretreated with the
mu-antagonist beta-funaltrexamine, the delta-antagonist naltrindole, or the
kappa-antagonist nor-binaltorphimine, each at the doses of 1, 10, and 100
micrograms/rat intracerebroventricularly. Serum IL-6 levels were measured 2
h later. The results show that mu-receptor blockade increases, whereas
delta-receptor blockade decreases IL-6 induction, suggesting that the fine
tuning exerted by opioids on the immune system may be achieved through a
balance of opposing effects. Moreover the three antagonists affect IL-6
induction by central and peripheral IL-1 beta with a similar pattern,
indicating that the brain endogenous opioid system plays a general role in
the regulation of this cytokine.
