Objective To observe the effect of electroacupuncture（EA） at "Huantiao"（GB 30） and "Weizhong"（BL 40） on the activation of glial cells

the expression of brain-derived neurotrophic factor（BDNF）

excitability and the number of dendritic spines of neurons in the spinal dorsal horn in rats with spared nerve injury（SNI） of sciatic nerve

and to explore the analgesic mechanism of EA on SNI.Methods PartⅠ:Sixty SD rats were randomly divided into a sham operation group

a model group

an EA group and a sham EA group

15 rats in each group.Except the sham operation group

the SNI rat model was established in the remaining groups.The rats in the sham operation group were only treated with incision without damaging the nerve.The rats in the EA group were treated with EA at "Huantiao"（GB 30） and "Weizhong"（BL 40） on the affected side

continuous wave

frequency of 2 Hz

current intensity of 1 m A

30 minutes each time

once a day

for 14 days.The rats in the sham EA group were treated with EA at points 0.5 cm next to "Huantiao"（GB 30） and "Weizhong"（BL 40） on the affected side;the manipulation

EA parameters and treatment course were the same as the EA group.The latency of thermal foot contraction reflex and the threshold of mechanical foot contraction reflex were detected 1 day before modeling and 3

7 and 14 days after modeling.Fourteen days after modeling

Western blot was used to detect the protein expressions of ionized binding adapter junction protein 1（Iba-1）

glial fibrillary acidic protein（GFAP）

BDNF and c-Fos in the spinal dorsal horn;the expressions of Iba-1 and c-Fos proteins in the spinal dorsal horn were detected by immunofluorescence staining;immunohistochemical method was used to detect the expression of GFAP protein in the spinal dorsal horn;Golgi staining was used to detect the number of dendritic spines in spinal dorsal horn neurons.PartⅡ:Thirty SD rats were randomly divided into a control group

a BDNF group and a BDNF+anti-Trk B group

10 rats in each group.The control group was treated with intrathecal injection of 10 μL mixture with 1︰1 of 0.9% sodium chloride solution and dimethyl sulfoxide（DMSO）;the BDNF group was treated with intrathecal injection of 10 μg rat recombinant BDNF dissolved in 10 μL mixture with 1︰1 of 0.9% sodium chloride solution and DMSO;the BDNF+anti-Trk B group was treated with intrathecal injection of 10 μg rat recombinant BDNF and 30 μg tyrosine kinase receptor B（Trk B） antibody dissolved in 10 μL mixture with 1︰1 of 0.9% sodium chloride solution and DMSO.The threshold of mechanical foot retraction reflex was detected 1 day before intrathecal injection and 1

3 and 7 days after injection.Seven days after injection

the expression of c-Fos protein in the spinal dorsal horn was detected by Western blot and immunofluorescence staining.Results PartⅠ:Compared with the sham operation group

3

7 and 14 days after modeling

the latency of thermal foot contraction reflex and the threshold of mechanical foot contraction reflex in the model group were decreased（P<0.05）;7 and 14 days after modeling

compared with the model group

the latency of thermal foot contraction reflex and the threshold of mechanical foot contraction reflex in the EA group were increased（P<0.05）.The expressions of Iba-1

GFAP

BDNF

c-Fos proteins and the number of neuronal dendritic spines in the spinal dorsal horn in the model group were higher than those in the sham operation group（P<0.05）;the expressions of Iba-1

BDNF

c-Fos proteins and the number of neuronal dendritic spines in the EA group were lower than those in the model group（P<0.05）.PartⅡ:3 and 7 days after intrathecal injection

the threshold of mechanical foot retraction reflex in the BDNF group was lower than that in the control group（P<0.05）;the threshold of mechanical foot retraction reflex in the BDNF+anti-Trk B group was higher than that in the BDNF group（P<0.05）.The expression of c-Fos protein in spinal dorsal horn in the BDNF group was higher than that in the control group（P<0.05）;the expression of c-Fos protein in spinal dorsal horn in the BDNF+anti-Trk B group was lower than that in the BDNF group（P<0.05）.Conclusion The analgesic effect of EA at "Huantiao"（GB 30） and "Weizhong"（BL 40） on SNI rats may be related to inhibiting the activation of microglia in the dorsal horn of the spinal cord

thereby blocking the signal of microglia-BDNF-neuron

and finally reducing the excitability of neurons.