Objective To observe the effect of electroacupuncture(EA)on expression of synaptic plasticity-related glutamate N-methyl-D-aspartate(NMDA)receptor subunit NR 1

gamma-aminobutyric acid(GABA)receptor subunits(Aβ2

B 1)

etc.in the amygdala in chronic neuropathic pain negative affection(CNPPNA)rats

so as to reveal its mechanism underlying pain relief.Methods Male Wistar rats were randomized into normal control

CNPPNA model

EA

and anesthesia+EA(AEA)groups(n=14in each group

8for quantitative RT-PCR and 6for immunofluorescence staining).The CNPPNA model was established by ligation of the left sciatic nerve and repeated electrical stimulation of the hindpaw plantar skin in the pain-paired compartment.EA was applied to bilateral"Zusanli"(ST 36)and"Yanglingquan"(GB 34)for 30 min

once daily for 7days.Thermal pain threshold(paw withdrawal latency

PWL)of the bilateral paws was measured by using a Tail-Flick Unit.The conditioned place aversion(CPA)was determined by using a CPA-paired compartment.The expression levels of GABAAβ2

GABAB 1

NMDA receptor subunit NR 1

postsynaptic density-95protein(PSD-95)

Piccolo genes in the right amygdala area were determined using quantitative RT-PCR

and the immunoactivity of metabotropic glutamate receptor subunit 1(mGluR 1)and GABAB 2in the basolateral amygdala(BLA)nucleus was detected using immunofluorescence staining.Results After modeling

PWL difference(PWLD)values of the model group were significantly increased(P<0.001)

and the time spent in the CPA-paired compartment was considerably decreased compared with the control group(P<0.001).After EA intervention for 3and 7days

the PWLD levels of both EA and AEA groups were apparently decreased(P<0.05)

and the time spent in the CPA-paired compartment was apparently increased in the EA and AEA groups(P<0.05)

suggesting apain relief and an improvement of the negative affection after EA intervention.Additionally

following EA

the apparently-decreased expression levels of GABAAβ2

GABAB 1

PSD-95

Piccolo genes and the reduced numbers of GABAB 2positive cells and NMDA-NR 1 mRNA as well as mGluR 1positive fiber numbers were remarkably increased in the EA group(P<0.05

P<0.001).The expression levels of Piccolo gene

GABAB 2and mGluR 1positive cells/fiber numbers were apparently lower in the AEA group than in the EA group(P<0.001).No significant differences were found between the EA and AEA groups in the PWLD

time spent in the CPA-paired compartment

and the expression levels of NMDA-NR 1

GABAAβ2

GABAB 1and PSD-95genes(P>0.05).Conclusion Repeated EA stimulation of ST 36-GB 34 has a role in relieving both sensory and affection dimensions of chronic pain in CNPPNA rats

which may be respectively related to its effects in up-regulating the expression of GABAAβ2

GABAB 1

NMDA-NR 1

PSD-95 and Piccolo genes

and in promoting the expression of mGluR 1and GABAB 2proteins and Piccolo gene in the amygdala.