OBJECTIVETo probe into the best parameter of electroacupuncture (EA) for treatment of inflammatory pain in the rat.

METHODSOne hundred and twenty Wistar rats were randomly divided into 12 groups, normal control group, model group and 10 EA groups including A1 B1 C1, A1 B1 C2, A1 B2 C1, A1 B2 C2, A2 B1 C1, A2 B1 C2, A2 B2 C1, A2 B2 C2 (A1 : 2 Hz, A2: 100 Hz; B1 : successive wave; B2: intermittent wave; C1: 0.1 mA, C2: 0.2 mA), A3 B3 C1 (4/20 Hz, disperse-dense wave, 0.1 mA) and A3 B3 C2 (4/20 Hz, disperse-dense wave, 0.2 mA). The rats of adjuvant-induced arthritis in all of the EA groups were treated by EA with selected different parameters once every day for 6 days. Pain thresholds and beta-endorphin (beta-EP) content in the local tissue of inflammation were used as indexes to compare analgesic effects of EA of different frequencies, waveforms and currents by orthogonal experiment design and other methods.

RESULTSThe optimized parameters of raising the pain threshold was: 100 Hz, 0.1 mA, intermittent wave. EA at 100 Hz was better than 2 Hz for increasing the content of beta-EP in local tissue of inflammation. The analgesic effect of EA at 4/20 Hz, 0.1 mA, disperse-dense wave on the inflammatory pain in the rat was not significant different with that at 100 Hz, 0.1 mA, intermittent wave (P > 0.05).

CONCLUSIONThe best parameters are 100 Hz, 0.1 mA and intermittent wave for EA treatment of inflammatory pain in the rat.