ObjectiveTo observe the effect of electroacupuncture(EA)on changes of expression of L-Arg transporter 2(CAT-2)m RNA and nitric oxide synthase(i NOS)m RNA and protein and contents of NO and c GMP of L4—L6 segments of spinal cord in rats with spared nerve injury(SNI)

so as to reveal its mechanism underlying reducing neuropathic pain.MethodsA total of 120 male SD rats were randomly divided into sham operation

model

EA and NOS inhibitor(N omega-Nitro-L-arginine methyl ester hydrochloride

L-NAME)groups

with 30 rats in each group. The neuropathic pain model was established by ligating and cutting the tibial nerve and the common peroneal nerve. EA(2 Hz

1—3 m A)was applied to"Weizhong"(BL40)and"Huantiao"(GB30)on the damaged hindlimb for 30 min

once daily from day 11 to 17 after SNI. Rats of the L-NAME group received i. p. of L-NAME(60 mg·kg

(-1)

·d(-1)·d

(-1)

)for 7 consecutive days.The mechanical pain threshold(PT)was determined before and 10 and 16 d after SNI

respectively. The expression levels of CAT-2 m RNA and i NOS m RNA

and i NOS protein in the L4—L6 segments of the spinal cord were detected by using reverse transcription-polymerase chain reaction(RT-PCR)and Western blot

respectively

and the contents of NO and cGMP of L4—L6 assayed using nitrate/nitrite reductase method and radioimmunoassay

respectively.Results After modeling

the PT was significantly decreased on day 10 and 16 after SNI in comparison with the sham operation group and their own baseline data of pre-operation in each group(P

<

0. 01)

and remarkably increased in the EA and L-NAME groups relevant to the model group on day 16(P

<

0. 01

P

<

0. 05). Compared with the sham operation group

the expression levels of CAT-2 mRNA and i NOS m RNA and protein

as well as the contents of NO_2(-1))for 7 consecutive days.The mechanical pain threshold(PT)was determined before and 10 and 16 d after SNI

respectively. The expression levels of CAT-2 m RNA and i NOS m RNA

and i NOS protein in the L4—L6 segments of the spinal cord were detected by using reverse transcription-polymerase chain reaction(RT-PCR)and Western blot

respectively

and the contents of NO and cGMP of L4—L6 assayed using nitrate/nitrite reductase method and radioimmunoassay

respectively.Results After modeling

the PT was significantly decreased on day 10 and 16 after SNI in comparison with the sham operation group and their own baseline data of pre-operation in each group(P

<

0. 01)

and remarkably increased in the EA and L-NAME groups relevant to the model group on day 16(P

<

0. 01

P

<

0. 05). Compared with the sham operation group

the expression levels of CAT-2 mRNA and i NOS m RNA and protein

as well as the contents of NO_2

-

/NO_3-/NO_3

-

and c GMP were significantly up-regulated in the model group(P

<

0. 05

P

<

0. 01). Following EA intervention

the levels of CAT-2 m RNA and i NOS m RNA and i NOS protein

and NO_2-and c GMP were significantly up-regulated in the model group(P

<

0. 05

P

<

0. 01). Following EA intervention

the levels of CAT-2 m RNA and i NOS m RNA and i NOS protein

and NO_2

-

/NO_3-/NO_3

-

and cGMP contents were all reversed in both EA and L-NAME groups(P

<

0. 05

P

<

0. 01). The effect of EA was significantly superior to that of L-NAME in raising the PT on day 16 after SNI(P

<

0. 05)

but obviously inferior to that of L-NAME in down-regulating the expression of CAT-2 m RNA and i NOS m RNA and protein(P

<

0. 05). No significant differences were found between the EA and L-NAME groups in down-regulating NO2-/NO3-and c GMP contents(P

>

0. 05).ConclusionEA intervention can effectively relieve neuropathic pain in SNI rats

which may be closely related to its function in suppressing L-Arg/NO/c GMP pathway in the lumbar spinal cord.