The Cross Effects of Needle Electrical Stimulation according to Electrode Placements on the Analgesia in Arthritic Rat Model

ABSTRACT

OBJECTIVE: To investigate the analgesic effect of needle electrical stimulation (NES) according to the electrode placement in acute arthritic rat model. METHOD: Male Sprague-Dawley rats (120 rats, 250+/-50 g) were injected with a mixture of 3% carrageenan and 3% kaolin into the right knee joint. Rats were randomly assigned into one of four groups Group I, control group (n=30); Group II, arthritic limb-induced control group (n=30); Group III, NES application group on the ipsilateral arthritic limb (n=30); Group IV, NES application group on the contralateral arthritic limb (n=30). We applied the NES (2 Hz, 200micro s, 20 min) to group III and IV. We assessedthe change of paw withdrawal latency (PWL) and the immunoreactivity of c-fos by immunohistochemistry at baseline, 4, 8, 12 and 24 hours after induction of arthritis. RESULTS: NES was more effective in Group III and IV than group II 8 hours after the induction of arthritis (p < 0.001) based on the results of PWLs and c-fos immunoreactivity. The analgesic effects of Group III were greater than those of group IV (p < 0.001). CONCLUSION: Contralateral NES on arthritic limb reduced pain in arthritic rat model as effectively as ipsilateral NES.