Ginsenosides that produce differential antinociception in mice

Ginsenoside Re, Rd, and Re induced antinociception in writhing and formalin tests among five representative ginsenosides: Rbl, Re, Rd, Re, and Rg(1). However, these ginsenosides had no effect in the tail-flick test. The antin ociceptive effects induced by three ginsenosides were dose dependent. ED50 was 20.5 (7.3-57.3 mg/kg) for Re, 17 (11.0-27.6 mg/kg) for Rd, and 3.5 (1-1 2 mg/kg) for Re in the writhing test and 62 (42-90 mg/kg,) for Re, 45 (20.5 -99.0 mg/kg) for Rd, and 82 (48-139 mg/kg) for Re in the second phase of th e formalin test. The antinociceptive effects were not blocked by the opioid receptor antagonist naloxone in the writhing and formalin tests. These thr ee ginsenosides did not affect motor function. Ginsenoside Re and Rd induce d hypothermia for 30 to 60 min, and ginsenoside Re induced hyperthemia afte r 150 min of treatment at doses of 100 mg/kg. These results suggest that gi nsenosides such as Re, Rd, or Re inhibit mainly chemogenic pain rather than thermal pain by the nonopioid system in mice. (C) 1999 Elsevier Science In c. All rights reserved.