RESUMEN
Objective: To observe the effect of 2 Hz electroacupuncture (EA) on long term depression (LTD) of synaptic transmission in the spinal dorsal horn in rats with neuropathic pain, so as to explore the central mechanisms of the antinociceptive effects of 2 Hz electroacupuncture on neuropathic pain. Methods: The neuropathic pain models were produced by tight ligation of the L5/L6 spinal nerves in Sprague Dawley rats. The C fiber evoked field potentials in the spinal dorsal horn were recorded with extracellular recording techniques. The parameters of the electroacupuncture were as follows: frequency of 2 Hz, wavelength of 0.6 ms, intensity of 1,2,3 mA lasting 10 min for each intensity, stimulation time of 30 min. The positive stimulating electrode was placed in acupoint “sanyinjiao” and the negative electrode in “zusanli”. Results: (1) 2 Hz electroacupuncture significantly decreased the amplitudes of C fiber evoked field potentials in the spinal dorsal horn in rats with neuropathic pain to (49.4?0.6)% of the control, compared with that (100.1?1.2) % of the control before EA (unpaired t test, P