Objective To observe the effect of electroacupuncture(EA) on the behavior

histomorphology and the expression of angiopoietin-1(Angpt-1) in rats with spinal nerve injury

so as to explore its mechanism on neuropathic pain. Methods Forty-five male SD rats were randomly divided into sham

model and EA groups(n=15 rats in each group). Spinal nerve ligation(SNL) of the L5 lumbar vertebra was performed to establish a rat model of neuropathic pain. The rats in the EA group were given EA at "Zusanli"(ST36) and "Kunlun"(BL60) of the operation side with continuous wave at a frequency of 2 Hz and an intensity of 1.5 mA once a day

30 minutes each time for 7 days. The sham group only exposed L5 spinal nerves without ligation. Mechanical withdrawal threshold(MWT) and thermal withdrawal latency(TWL) were observed and recorded before modeling and on days 3

5

7

10

12 and 14 after modeling. L4—L6 segments of spinal cord were taken and the morphological changes of spinal dorsal horn were observed by HE staining. The changes of spinal dorsal horn nerve fiber structure were observed by silver plating staining. Angpt-1 expression was detected by Western blot and immunohistochemistry. Results Compared with the sham group

the model group had significant reductions in MWT and TWL at each time point(P<0.01); compared with the model group

the EA group had significant increases in MWT and TWL on days 10

12 and 14 after intervention(P<0.05

P<0.01). HE staining showed that in the model group

the spinal dorsal horn showed degeneration and necrosis of neurons

nuclear fixation and shrinkage

and loose surrounding tissues. The degree of tissue damage of the EA group was milder than that of the model group. The silver staining results showed the model group had obvious neuronal fibrillary tangles

while there were fewer neuronal fibrillary tangles in the EA group. Compared with the sham group

the Angpt-1 expression in the model group was significantly decreased(P<0.01)

and compared with the model group

the EA group had a significant increase in the expression of Angpt-1(P<0.01). Conclusion EA can promote the recovery of nerve function in SNL rats by up-regulating Angpt-1 expression.