Effect of Danggui Sini Decoction on the Behaviour and Dorsal Root Ganglion TRP Channel of Neuropathic Pain in CCI Rats

Danggui Sini decoction, a traditional Chinese medicine formula, has been extensively used as a remedy for neuropathic pain and other diseases in recent years. To explore whether Danggui Sini decoction can alleviate mechanical pain, thermal hyperalgesia, and cold pain at the same time, the role of temperature-sensitive transient receptor potential channel in neuropathic pain and the therapeutic effect of Danggui Sini decoction on neuropathic pain as well as the impact on the transient receptor potential pathway were explored in the present study. One hundred and twentyeight Sprague Dawley rats were separated randomly into 4 groups; the sham-operated group, chronic constriction injury of sciatic nerve model group, pregabalin group, and Danggui Sini decoction-treated group. The rats in the sham-operated group underwent surgery, but no nerve was ligated. The rest of the rats were subjected to sciatic nerve ligation. Rats in Danggui Sini decoction-treated group could be irrigated to Danggui Sini decoction. Rats in the sham-operated group and chronic constriction injury model group were gavaged with saline. Rats in pregabalin group were given pregabalin. Behavioral tests conducted were, acetone test and cold plate, hot plate experiment, and von Frey filaments on 4, 7, 14, 21st day, and then dorsal root ganglion neurons were take out. Nerve ligation from the ipsilateral L4-6 dorsal root ganglion were measured TRPM8, TRPA1, TRPV1, TRPV2, TRPV3, and TRPV4 proteins expression by immunofluorescence staining and Western-blot method. Danggui Sini decoction could significantly inhibit the cold allodynia and the mechanical allodynia. The immunofluorescence studies showed that the model group of dorsal root ganglia on TRPM8, TRPA1, TRPV1, TRPV2, TRPV3, and TRPV4 proteins were decreased. Western-blot results showed the the expression of TRPM8, TRPA1, TRPV1, TRPV2, TRPV3, and TRPV4 proteins in Danggui Sini decoction-treated group was reduced. Danggui Sini decoction could not only suppress the cold allodynia, but also alleviate mechanical allodynia and thermal hyperalgesia. Danggui Sini decoction could down-regulate abnormally high expression of temperature-dependent transient receptor potential channel protein.