Increase in serum level of interleukin-1 alpha mediates morphine anti-inflammatory effect in carrageenan-induced paw oedema in mice.

In the present studies we examined the effects of an intra-peritoneal injection of morphine (7 mg/kg) on carrageenan-induced paw oedema in mice. Carrageenan-induced paw oedema was measured by mercury plethysmometer and was maximal at hour 3, and pretreatment with morphine could reduce the oedema significantly. At the same time the serum levels of interleukin-1 alpha (IL-1 alpha) were increased. Pretreatment with naloxone and dexamethasone abolished morphine anti-inflammatory while decreasing IL-1 alpha serum levels, significantly. These findings suggest that an increase in serum levels of IL-1 alpha plays an important role in the anti-inflammatory effect of morphine.