Objective To investigate the effect of electroacupuncture(EA) on pain behaviors and expression of spinal transcription factor GATA-binding Protein 4(GATA4) and adenosine A1 receptor in neuropathic pain rats

so as to explore its mechanism underlying pain relief.Methods The present study includes 2 parts. In the first part

18 SD rats were randomly divided into control

adenovirus short-hairpin interference RNA for GATA4(AV-shGATA4 RNA) and adenovirus empty vector(AV-control short-hairpin RNA

AV-shCTRL) groups

with 6 rats in each group. The expression of GATA4 protein in the lumbar spinal cord(L4—L6) was detected to evaluate the transfection efficiency of AV-shGATA4 RNA(silencing GATA4 expression). In the second part

thirty SD rats were randomly divided into 5 groups

namely sham operation

CCI model

EA

EA+AV-shGATA4 RNA

and EA+AV-shCTRL groups

with 6 rats in each group. The neuropathic pain model was established by chronic constriction injury(CCI) of the right sciatic nerve. On the 7 th day following modeling

EA was applied to the right "Zusanli"(ST36) and "Taichong"(LR3)(1 mA

2 Hz/100 Hz) for 30 min. Rats of the EA+AV-shGATA4 RNA and EA+AV-shCTRL groups received intrathecal injection of AV-shGATA4 RNA and AV-shCTRL(1×10

(11)

PFU/mL

10 μL)at the spinal L4—L6 segments

separately

48 h before EA intervention. The mechanical pain threshold and thermal pain threshold of the affected limb were detected before molding

7 days following molding and 60 min after EA. The expressions of adenosine A1 receptor and GATA4 protein in the spinal cord(L4—L6) were detected by Western blot.Results Outcomes of the first part showed that compared with the control group

no significant changes were found in the mechanical and thermal pain thresholds in both AV-shCTRL and AV-shGATA4 RNA groups and in the expression of spinal GATA4 protein of the AV-shCTRL group(P

>

0.05). The expression of spinal GATA4 protein of the AV-shGATA4 RNA group was significantly lower than that of the AV-shCTRL group(P

<

0.05). In the second part of the study

before CCI modeling

there were no significant differences among the five groups in the mechanical and thermal pain thre-sholds(P

>

0.05). On the 7 th day following modeling

the mechanical and thermal pain thresholds were significantly lowered in compa-rison with their own pre-modeling of each group and with the sham operation group(P

<

0.05). At 60 min after EA and compared with the model group

the mechanical and thermal pain thresholds were significantly increased in both the EA and EA+AV-shCTRL groups(P

<

0.05) but not in the EA+AV-shGATA4 RNA group(P

>

0.05)

suggesting a critical involvement of GATA4 in EA analgesia. The expression levels of adenosine A1 receptor and GATA4 protein were significantly increased in the model group than in the sham operation group(P

<

0.05)

and considerably further up-regulated in both EA and EA+AV-shCTRL groups(P

<

0.05)

rather than in the EA+AV-shGATA4 RNA group(P

>

0.05)

suggesting that the effects of EA in up-regulating the expression of A1 receptor and GATA4 were eliminated after silencing GATA4 protein. Conclusion EA of ST36 and LR3 can relieve pain by increasing the expression of adenosine A1 receptor of the lumbar spinal cord in neuropathic pain rats

which is probably mediated by GATA4 protein.