The analgesic activities of Stauntonia brachyanthera and YM through regulating inflammatory mediators and directly controlling the sodium channel prompt.

The analgesic studies on Stauntonia brachyanthera, a traditional Chinese folk medicine used to treat headache, pains and inflammatory diseases in local areas, showed that the EtOH extracts (EESB) and the characteristic ingredient YM could significantly inhibit the acetic acid-induced writhing responses by 43.1% and 78.95%, and decrease the xylene-induced ear edemas by 48.9% and 21.4%, respectively. EESB could significantly increase pain threshold of mice in hot-plate test, but the effect of YM was not obviously. Further study in formalin test showed the inhibitory effect of YM in 2 phase was more significant than that in 1 phase, revealed the peripheral analgesic activity of YM. The ELISA and Western Blot analysis suggested that the analgesic mechanisms of YM were related to the inhibitions of the expressions of TNF-α, IL-1β and IL-6, and down-regulations of Na1.8 protein in the left side of L4-6 DRG regulated by MAPKs, in which the levels of p-ERK, p-JNK and p-p38 were all decreased. In addition, the electrophysiological experiments indicated YM could reduce the Nav1.8 currents by 46.01% in small-diameter DRG neurons. Therefore, the analgesic activity of S. brachyanthera might be based on the regulation of inflammatory mediators and the directly control of the sodium channel prompt.