Antinociceptive profiles and mechanisms of orally administered curcumin in various pain models

Antinociceptive profiles of curcumin in ICR mice were examined. Curcumin administered orally (from 1 to 10 mg/kg) showed an antinociceptive effect in a dose-dependent manner as measured in the acetic acid-induced writhing test. Duration of antinociceptive action of curcumin was maintained at least for 60 min. Moreover, cumulative response time of nociceptive behaviors induced with intraplantar formalin injection was reduced by curcumin treatment during second phase. Cumulative nociceptive response time for intrathecal injection of substance P (0.7 μg) or glutamate (20 μg) was diminished by curcumin. Intraperitoneal pretreatment with naloxone (opioid receptor antagonist) or methysergide (5-HT serotonergic receptor antagonist)-attenuated antinociceptive effect induced by curcumin in the writhing test, whereas yohimbine (α2-adrenergic receptor antagonist) did not affect antinociception induced by curcumin, suggesting that curcumin shows antinociceptive property in various pain models, and this antinociceptive effect of curcumin may be mediated by opioidergic and serotonergic receptors, but not α2-adrenergic receptor.