[The extensiveness and specificity of analgesia of electroacupuncture (EA) at different points on the nociceptive responses of neuron in spinal dorsal horn].

The experiments were performed in anaesthetized rats. The responses of convergent neurons in spinal dorsal horn to noxious stimuli (10mA, 2ms) given at the hindpaw receptive field were recorded extracellularly by glass microelectrodes. The effects of EA on the nociceptive response were observed. EA was applied on ipsilateral "Zusanli" or "Xiaguan" point with high and low intensity. EA (18V, 100Hz) applied on ipsilateral either "Zusanli" or "Xiaguan" could produce strong inhibition on nociceptive responses of convergent neurones (62.74 +/- 4.94% and 64.24 +/- 7.30%). EA (2V, 100Hz) of "Zusanli" also obviously inhibited the nociceptive responses (52.05 +/- 6.69%). But the same EA of "Xiaguan" lacked this inhibitory effect (9.50 +/- 7.67%). There was statistically significant difference between EA effects of "Zusanli" and "Xiaguan" (P < 0.001) when intensity of EA is lower. These results suggested that analgesia of high intensity EA is extensive, but that of low intensity EA is produced only when the point is in the same or nearby spinal segment with nociceptive field, showing the extensiveness and specificity of EA analgesia of different points.