After intrathecal administration, HWL were measured with hot plate each every 5 minutes in the following 60 minutes, and the analgesia index (AI) was calculated subquently.

• 给药后每隔5min采用热板测定一次大鼠的缩爪反应潜伏期(HWL)，然后换算出大鼠的疼痛指数(AI)，直至60min为止。