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OBJECTIVE:To investigate how electroacupuncture (EA) at Zusanli (ST 36) with varying intensities of stimulation affects dorsal root nerve signals in normal rats.METHODS:Adult female Wistar rats were examined after drug-induced anesthesia and isolation of the L4 dorsal root associated with the Zusanli (ST 36) acupoint,using bipolar platinum electrodes.We applied EA at Zusanli (ST 36) with a continuous wave waveform for 1 min,and recorded action potentials in the L4 spinal cord dorsal root nerve with a frequency of 5 Hz and various current intensity levels (approximately 1-4 mA).In addition,we tested EA with a frequency of 15 Hz and current intensity of 1-4 mA.The L4 spinal cord dorsal nerve bundle action potentials were measured for 1 min of EA.To analyze the discharge frequency,we used the maximum Lyapunov exponent and Lempel-Ziv (LZ) complexity.RESULTS:At a fixed frequency,with increasing intensity of EA,dorsal root nerve filament discharge frequency revealed an initial increase,followed by a decreasing trend.A stimulation intensity of 3 mA induced a significantly greater discharge frequency,compared with stimulation intensities of 2 and 4 mA.EA stimulation evoked neuroelectric signals with chaotic characteristics.Increased intensity led to an initial increase in LZ complexity which then decreased,with a stimulation strength of 3 mA inducing the highest level of LZ complexity.CONCLUSION:EA of different intensities can induce nerve action potential encoding with different features.