Objective To observe the effect of electroacupuncture(EA) of "Huantiao"(GB 30) and "Weizhong"(BL 40) on the mechanical pain threshold and the long-term potentiation(LTP) of the spinal dorsal horn in rats with neuropathic pain.Methods Thirty SD rats were randomized into control(sham-operation)

model and electroacupuncture(EA) groups

with 10 cases in each.The neuropathic pain model was established by ligature and transaction of the popliteal nerve and common peroneal nerve.EA(2 Hz

1 mA) was applied to "Huantiao"(GB 30) and "Weizhong"(BL 40) on the affected side for 30 min

once daily for 7 days.The mechanical pain threshold of the paw was detected before and after modeling and EA.LTP of C-fiber stimulation(2 mA

0.5 ms

100 Hz

interval 10 s

4 strains) evoked field potentials in spinal dorsal horn(L4/L5) was recorded in rats under anesthesia.Results Compared with control group

the pain threshold of model group reduced significantly from the 1st day on after ligature and transaction of the nerve(P<0.01)

while 14 days after EA

it elevated evidently in comparison with model group(P<0.01)

suggesting an increase of the mechanical pain threshold after EA.Comparison of the variance rates of C-fiber induced LTP of the field potential among the 3 groups showed that the variance rate of EA group was significantly lower than that of model group(P<0.01).Self-comparison of EA group showed that after EA

the variance rate of LTP reduced significantly(P<0.01).Conclusion EA of "Huantiao"(GB 30) and "Weizhong"(BL 40) can significantly relieve neuropathic pain in rats with nerve injury

and inhibit C-fiber high-frequency-stimulation induced LTP due to central sensitization induced abnormality synaptic transmission.