Ligustilide inhibits spontaneous and agonists- or K+ depolarization-induced contraction of rat uterus

In the present study, the effects of ligustilide (LIG) on uterine contraction in vitro were investigated. In isolated rat uterine, LIG (2-8 microg/ml) inhibited the spontaneous periodic contraction in a concentration-dependent manner (EC(50)=4.4 microg/ml, 95% confidence interval 2.7-6.1 microg/ml), and attenuated prostaglandin F2alpha (PGF(2)alpha)- or acetylcholine chloride (Ach)-induced uterine contractions. At 8 microg/ml, LIG nearly completely blocked the PGF(2)alpha-induced contractions (95.3%). In the case of Ach-induced contraction, about 73.9% was inhibited by LIG at this dosage. It was also observed that LIG affected significantly oxytocin-induced increase in the contraction of uterine horns that were incubated not only in the Locke solution but also in a Ca(2+)-free solution. In addition, LIG caused concentration-dependent inhibition of uterine contraction induced by K(+) (56.3 Mm) depolarization, reaching the significant level at 2 microg/ml (EC(50)=3.3 microg/ml, 95% confidence interval 2.5-4.1 microg/ml). The findings clearly show that LIG has multiple effects on the uterine smooth muscles, suggesting that LIG possesses a non-specific antispasmodic function. The data also imply strongly that LIG is one of active ingredients of Danggui and has the potential to be developed into an effective drug for the prevention and treatment of primary dysmenorrhoea.