Analgesic sites of total alkaloids in Papaver nudicaule / 中草药

ABSTRACT

Objective To study the analgesic sites and mechanism of total alkaloids in Papaver nudicaule (TAPN). Methods The sites of analgesic action of TAPN were observed by adopting Formalin test and two different routes of intracerebroventricular (icv), intrathecal (ith) in mice and rats and comparing ED 50 of TAPN in writhing reaction in mice induced by acetic acid by ip and iv administration. Results TAPN significantly lowered pain score of the early and late phase of Formalin response and was more sensitive in the late phase. Inhibition of TAPN at the same dose by ip administration in writhing reaction in mice induced by acetic acid was stronger than that by iv. The ED 50 value of TAPN at any time by ip administration was lower than that by iv administration. By means of central microinjection, TAPN by icv administration induced remarkable analgesic effect in mice, but TAPN by ith administration had no significant analgesic effect. Conclusion The sites of analgesic action of TAPN are mainly at periphery. TAPN has also central analgesic effect, and the site may be at the level above the spinal cord.