Analgesic effect and mechanism of the three TCM-herbal drug-combination Tou Feng Yu pill on treatment of migraine.

It is well known that pain is one of the most important characteristics of migraine. Therefore, it is important and interesting to investigate the analgesic effect and mechanism of drugs which are used to treat migraine. Tou Feng Yu pill (TFY) is a traditional Chinese herbal medicine, consisting of the three Chinese herbal drugs Radix Angelicae dahuricae (Baizhi), Rhizome Ligustici (Chuanxiong) and Folium Camelliae sinensis (green tea) for the treatment of migraine. In this study, we found that TFY could significantly reduce the writhing times induced by acetic acid and licking foot response induced by formalin, and extend the writhing latent period. But the analgesic effect was not observed at hot-plate test. Meanwhile, experimental migrainous model induced by nitroglycerin was used to investigate the therapeutic effect of TFY. Compared with the control group, the levels of plasma calcitonin gene related to peptide (CGRP), serum nitric oxide (NO) and contents of brain dopamine (DA) in TFY administration groups were significantly decreased, and the levels of plasma endothelin (ET) and contents of brain 5-hydroxytryptamine (5-HT) and norepinephrine (NE) were remarkably increased, also the ratio of ET/NO was clearly corrected. Furthermore, the improving effect of behavior abnormality was observed in TFY administration rats. Meanwhile, isolated vascular ring test indicated that TFY had an significant effect on vasomotion, and antagonize vasospasm; moreover TFY also could increase cerebral blood flow (CBF) and reduce cerebrovascular resistance index (RI) in normal rabbits, which verified the effect of TFY on vasomotion and abnormal hemorheology. All the results indicate that TFY has an effective therapeutical action on migraine, which may be related to three aspects as following: firstly, adjusting the level of neurotransmitters, neuropeptides and vasoactive substances, relieving neurogenic inflammation; secondly, improving vasomotion, increase cerebral blood flow, then improving hemorheology; finally, increasing pain threshold, relieving or preventing headache. These findings provide additional pharmacological information and may contribute for the further study and use of TFY as a phytomedicine.