Objective To observe the effect of electroacupuncture(EA) at "Futu"(LI 18)

etc.on the pain threshold and expression of metabotropic glutamate receptor subtype 5(mGluR 5)

cyclic adenosine monophosphate(cAMP)

mitogen-activated protein kinase(MAPK)

cAMP responsive element binding protein(CREB) genes in the cervico-spinal dorsal region in rats with neck incision pain so as to analyze its underlying analgesic mechanism in performing thyroid surgery.Methods Forty male Wistar rats were randomly divided into control

model

Futu(LI 18)

Hegu(LI 4)-Neiguan(PC 6)

Zusanli(ST 36)-Yanglingquan(GB 34) groups

with 8 cases in each group.Neck-incision pain model was established by making a longitudinal incision along the midline of the neck under anesthesia(isoflurane) except rats in the control group.EA(2 Hz/15 Hz

1-2 mA) was applied to bila-teral LI 18

LI 4-PC 6 and ST 36-GB 34 for 30 min

4 h

24 h and 48 h after modeling

respectively.The thermal pain threshold was detected before modeling

and before and after each treatment.After removing the ventral part

the spinal tissue of the cervical 1-4 segments was collected for detecting the expression of mGluR 5

cAMP

MAPK

CREB genes by using quantitative real-time-PCR technique.Results In comparison with the control group

the pain threshold of the model group was decreased obviously(P<0.05).Compared with the model group

the pain thresholds of the LI 18 and LI 4-PC 6 groups were upregulated markedly after treatment(P<0.05).No significant differences were found between the LI 18 and LI 4-PC 6 groups

and between the model and ST 36-GB 34 groups in pain thresholds(P>0.05).Compared with the control group

the expression le-vels of mGluR 5 mRNA

cAMP mRNA and CREB mRNA in the cervico-spinal cord were upregulated significantly in the model group(P<0.05).While in comparison with the model group

cervico-spinal cAMP mRNA

and CREB mRNA were down-regulated markedly(P<0.05) and mGluR 5 mRNA was down-regulated moderately(P>0.05) in the LI 18 group

rather than in the LI 4-PC 6 and ST 36-GB 34 groups(P>0.05).Conclusion EA-LI 18 can significantly suppress neck incision pain induced pain reaction

which may be closely associated with its functions in down-regulating expression levels of intracellular cAMP mRNA and CREB mRNA in the cervico-spinal cord.