Objective To observe the effect of deep electroacupuncture(EA)stimulation of"Huantiao"(GB 30)on the functional and pathological changes and nerve growth factor(NGF)expression of the damaged sciatic nerve in rats

so as to study its mechanisms underlying reliving sciatica.Methods Forty-eight SD rats were randomly divided into normal

model

deep EA and shallow EA groups(n=12in each group).The sciatic nerve injury model was established by mechanical clamp of the sciatic nerve stem.For deep and shallow EA

the acupuncture needles were inserted into GB 30about 16mm and 7mm

respectively. The EA treatment was given 20min

once daily for 14days.The evoked potentials of the injured sciatic nerve stem responding to electrical stimulation were recorded by using a biophysiological experimental system for calculating the motor conduction velocity. Pathological changes of the sciatic nerve were displayed by H.E.stain.The expression of NGF and Fos proteins was detected by immunohistochemistry.Results In comparison with the normal group

the conduction velocity and the amplitude of the evoked potentials of the sciatic nerve were significantly decreased in the model group(P<0.05).Following EA

both conduction velocity and amplitude of the evoked potentials in the deep EA group

and the conduction velocity in the shallow EA group were considerably increased(P<0.05).The therapeutic effects were significantly better in the deep EA group than that in the shallow EA group(P<0.05).No significant differences were found between the shallow EA and model groups in the amplitude of evoked potentials(P>0.05)

and no significant changes of latencies of the evoked potentials in the four groups(P>0.05).In the model group

the disorganized nerve fibers axons

myelin and Schwann cells of the damaged sciatic nerve were found

which became milder in the EA groups particularly in the deep EA group.In regard to the NGF and Fos immunoactivity of the injured sciatic nerve

the expression levels of both NGF and Fos proteins were obviously higher in the model group than in the normal group(P<0.05).After EA stimulation

NGF expression was further significantly up-regulated in both deep and shallow EA groups(P<0.05)

and Fos protein expression was notably down-regulated in the deep and shallow EA groups(P<0.05).The expression of NGF was significantly higher and Fos protein was obviously lower in the deep EA group than in the shallow EA group(P<0.05).ConclusionDeep EA stimulation of GB 30can improve the pathological changes and function of the injured sciatic nerve in the rat

which is closely associated with its effects in up-regulating NGF expression and down-regulating Fos expression.The deep EA is relatively better in the therapeutic effect.These facts may be one of the mechanisms of EA in relieving sciatica in clinic practice.