Antagonistic effect of pseudoginsenoside-F11 on the behavioral actions of morphine in mice

The antagonistic effect of pseudoginoside-F11 (PF11) on the various actions of morphine was studied in mice. The results demonstrated that PF11, at th e doses of 4 and 8 mg/kg, PO, significantly inhibited morphine (10 mg/kg, S C)-induced memory impairment in the Morris water maze test. PF11, at 4 mg/k g, PO, did not influence conditioned place preference per se, yet markedly blocked the conditioned place preference to morphine. PF11,at the doses of 4 and 8 mg/kg, PO, also significantly antagonized morphine (5 mg/kg, SC)-in duced analgesia tested by tail pinch method. PF11, at 4 mg/kg, PO, did not influence locomotor activity per se, yet inhibited the development of the r everse tolerance, as shown by the increase in locomotor activity, to morphi ne. At the doses of 4 and 8 mg/kg, PO, PF11 significantly antagonized the d evelopment of analgesia tolerance to morphine in the tail pinch test. Thus, the above results demonstrate for the first time that PF11 can antagonize some actions of morphine. However. the mechanism of action of PF11 merits f urther evaluation. (C) 2000 Elsevier Science Inc.