[Effects of electroacupuncture at "Zusanli" (ST 36) on ERK1/2 phosphorylation in the dorsal horn of spinal cord of the rat].
OBJECTIVE
To observe the effect of electroacupuncture at Zusanli (ST 36) on phosphorylated extracellular signal-regulated kinase 1/2 (pERK1/2) in the dorsal horn of spinal cord induced by plantar inflammation in the rat.


METHODS
All the rats were randomly divided into 5 groups: normal control group, simple electroacupuncture group, formalin group, formalin plus ipsilateral electroacupuncture group and formalin plus contralateral electroacupuncture group. The acute inflammation animal model was made by injection of 100 microL of 4% formalin into the right posterior foot pad. Electroacupuncture was given at "Zusanli" (ST 36) for 30 min, with sparse-dense waves, frequency 2-15 Hz, and intensity 2-3 mA. One and a half hours latter, the rats were killed under anesthesia, and pERK1/2 expression in the lumbar dorsal horn were investigated with immunohistochemical method.


RESULTS
The positive cells were rarely seen (6.45 +/- 1.05) in the superficial spinal cord in the control group; a few cells (14.07 +/- 3.19) in ipsilateral superficial spinal cord were found in the electroacupuncture group. The number of pERK1/2-positive neurons (26.57 +/- 4.93) in lamina I - II0 of the ipsilateral dorsal horn in the formalin group increased significantly. After electroacupuncture at ipsilateral Zusanli (ST 36), the number of positive cells (20.79 +/- 5.21) had a tendency to decrease, but with no statistically significant difference. However, after electroacupuncture at contralateral Zusanli (ST 36), the number of positive cells (14.75 +/- 3.03) significantly decreased as compared with the non-acupuncture group (P < 0.05).


CONCLUSIONS
The inhibition of ERK1/2 phosphorylation in the spinal cord dorsal horn by electroacupuncture is possibly involved in acupuncture analgesic effect.
Song
Le
L
Institute of Neurosciences, Fourth Military University, Xi'an 710032, China.
Zhu
Zheng-hua
ZH
Duan
Xiao-li
XL
Liu
Xiao-jun
XJ
Fan
Juan
J
Ju
Gong
G
Wang
Bai-ren
BR
D015667:Acupuncture Analgesia; D015669:Acupuncture Points; D000818:Animals; D015671:Electroacupuncture; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D010766:Phosphorylation; D020671:Posterior Horn Cells / Q000201:enzymology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3