In the endotoxin-induced inflammation, interleukin-10 reduced significantly, and in a dose-dependent manner, the inflammatory pain as assessed by mechanical and thermal tests. The levels of Tumour Necrosis Factor (TNF)alpha and NGF were upregulated at 1.5 h whereas those of IL-1beta at 6 h after ET injection. IL-10 downregulated the levels of TNFalpha (from 4974.75 +/- 875.78 to 1008 +/- 350 pg/hind paw), NGF (from 352.9 +/- 46.7 to 33.9 +/- 2.4 pg/hind paw) and IL-1beta (from 2773.88 +/- 423.96 to 1108 +/- 399.56 pg/hind paw). These data suggest that IL-10 inhibits ET-induced hyperalgesia by downregulation of TNFalpha, IL-1beta and NGF production.