Objective: To explore the effect of electroacupuncture (EA) on expression of c-fos in the spared dorsal root ganglia (DRG) of partially dorsal rhizotomized cats so as to analyze the correlation between c-fos and the effect of acupuncture in promoting plasticity of the spinal cord.Methods: Ten adult cats were randomly and evenly divided into control group and acupuncture group. All the cats underwent unilateral section of L 1～L 5 and L 7～S 2 DRG with the L 6 spared. In acupuncture group

EA (98 pulses/min

duration of 30 min) was applied to “Zusanli”(ST 36) and “Xuanzhong”(GB 39)

“Futu”(ST 32) and “Sanyinjiao”(SP 6) alternatively which are innervated by L 6. After surviving for 7 days

these animals were killed. L 6 DRG of every group was taken out to be cut into 20 μm sections that were then stained with immunohistochemical technique (ABC method). The distribution and the number of c-fos positive neurons in the spared DRG (L 6) of each animal were observed and counted under light microscope. Results: After acupuncture

the number of c-fos positive neurons (medium and small size neurons) in the spared DRG increased apparently than that of control group (161±31 vs 98±27

P<0.05)

suggesting that the therapeutic effect of EA may be mediated mainly by the medium size and small size neurons in DRG and c-fos possibly plays a role in the process of acupuncture in strengthening the plasticity of the spinal cord. Conclusion: EA of acupoints may generate up-regulation of expression of c-fos in the spared DRG.