Objective To observe the influence of Electroacupuncture(EA)stimulation of different distal-proximal acupoints combination groups on pain reaction

spinal p 38mitogen-activated protein kinase(p 38MAPK)expression and cyclic adenosine 3'

5'-monophosphate(cAMP)content in experimental lumbago rats.Methods Seventy-eight male SD rats were randomized into normal

model

sham operation

EX-B 2-BL 25(proximal acupoints

PA)

BL 40-BL 60(distal acupoints

DA)and DA+PA groups.The lumbago model was established by implanting the autologous nucleus pulposus to the site close to the left L 5dorsal root ganglion and the surface of dura mate of spinal cord.EA(2Hz/100 HZ

1-3mA)was applied at bilateral EX-B 2-BL 25 or BL 40-BL 60 or both for 20 minutes

once daily for 7days.The mechanical pain threshold was measured

and the expression of p 38 MAPK in the lumbar spinal cord was detected by immunohistochemistry and Western blot

separately.The content of cAMP in spinal cord(L 4-L 6)was measured by enzyme-linked immunosorbent assay(ELISA).Results After modeling

the mechanical pain threshold percentages were significantly decreased on day 3

5and 7(P<0.01)

and after EA stimulation of DA

PA and DA+PA

the decreased pain threshold was significantly increased at the 3time-points(P<0.01)

and the effects of both PA and DA+PA were markedly superior to that of DA(P<0.05

P<0.01).Following modeling

lumbar spinal p38 MAPK immunoactivity and protein expression

and cAMP content were obviously up-regulated(P<0.01).Compared with the model group

the levels of p 38 MAPK immunoactivity and protein expression in the 3EA groups and the sham group

and cAMP contents in both PA and DA+PA groups(not in the DA and sham groups)were considerably down-regulated(P<0.01

P<0.05).Conclusion EA stimulation of distal+proximal acupoints and proximal acupoints near the focus can raise pain threshold in lumbago rats

which may be associated with their effects in suppressing lumbago-induced increase of expression of spinal p 38 MAPK protein and cAMP content.The effects of EA of distal+proximal acupoints and proximal acupoints are better than those of EA of simple distal acupoints.