Ligustilide attenuates pain behavior induced by acetic acid or formalin.

Danggui is a popular traditional Chinese medicinal (TCM) herb, which has long been used clinically to treat primary dysmenorrhoea. In a recent study, we demonstrated that ligustilide (LIG), one of the main compounds of Danggui essential oil, has multiple effects on uterine smooth muscles and possesses a non-specific antispasmodic function, which suggests that LIG might play a major role in the therapeutic activity of Danggui in primary dysmenorrhoea. Since pain is the main syndrome of dysmenorrhea, the present investigation was carried out to evaluate the analgesic activity of LIG in vivo. LIG was intra-gastrically administered to animals. We demonstrated for the first time that LIG could cause a significant dose-related reduction of acetic acid-induced writhing response and formalin-induced licking time in both the early and late phases. These results showed that LIG possessed antinociceptive and anti-inflammatory activities. These findings plus the data we reported recently implied that LIG not only has an active dilatory effect on myometrium but also an effective role in reducing the neurogenic and inflammatory pain, thus having the potential to be developed into an effective drug for the treatment of various pain syndromes including primary dysmenorrhoea.