[Mechanism of electroacupuncture on "Zusanli (ST 36)" for chemotherapy-induced peripheral neuropathy]

To observe the effects and duration of electroacupuncture on the mechanical pain threshold induced by paclitaxel and explore its analgesic mechanism.

Sixty-four C57BL/6J male mice were randomly divided into 4 groups, a normal+sham EA group, a normal+EA group, a medicine+sham EA(Med+ sham EA) group, a medicine + EA (Med + EA) group, 16 cases in each group. The model of chemotherapy-induced peripheral neuropathy was established with paclitaxel intraperitoneal injection on the 1st, 3rd, 5th, 7th day in the Med + sham EA group and the Med + EA group. EA of 30 min was used on bilateral "Zusanli (ST 36)" on the 9th, 11th, 13th, 16th, 18th, 20th, 23rd, 25th, 27th, 30th day in the EA groups, 2 Hz/100 Hz and 1~ 1.5 mA. Acupuncture was applied on the same acupoint at the same times in the sham EA groups. Mechanical pain thresholds were tested by VonFrey before and after model establishment, namely on the 8th, 14th; 21st and, 28th day. The heart blood of 8 mice was drawn quickly to collect serum in every group on the 31st day, and the contents of tumor necrosis factor α (TNF-α), interleukin-1α (IL-1α), interleukin-1β (IL-1β) in proinflammatory cytokine were examined by ELISA. Mechanical pain thresholds were tested by VonFrey for the rest 8 mice of each group until there was no apparent difference in the two paclitaxel groups once a week,namely on the 35th, 42nd, 49th day.

The pain thresholds of each group were not statistically different before model establishment (P > 0.05). After model establishment (on the 8th day), thresholds of the paclitaxel groups were lower than those of the normal groups (all P < 0.05). After EA, the mechanical pain thresholds of the Med + EA group were higher than those of the Med + sham EA group at all the time points, and there was statistical difference on the 14th, 21st and 28th day (all P < 0.05). The analgesic effect was lasting to the 49th day. The contents of TNF-α, IL-1α, IL-1β of the Med + EA group were decreased than those of the Med+sham EA group in different degree, with statistical significance of IL-1α (P < 0.05).

EA can effectively treat paclitaxel-induced peripheral neuropathy,and the analgesic mechanism is probably related to decreasing the proinflammatory cytokine.