[The influence of lesion of different areas of sensorimotor cortex on effects of EA on NRM neurons].

The purpose of the experiment was to study whether the effects of electroacupuncture (EA) on neurons in nucleus raphe magnus (NRM) were influenced by lesion of different areas of sensorimotor cortex (SM) in rats. Unit discharges of NRM and their nociceptive response to stimulation of tail tip were recorded extracellularly with glass microelectrode. The excitatory type neurons of NRM were selected using of the experiments. 1. The effects of bilateral "Zusanli" point on 31 NRM neurons were observed in control group. EA had a tendency to activate NRM neurons, but obviously inhibited nociceptive response of the neurons in 0-30 minutes (P less than 0.01). 2. After resection of bilateral hindlimb areas of SM, the effects of EA on 31 units in NRM were observed. EA could obviously activate NRM neurons, increasing spontaneous firing rates to 115.3 +/- 20.3% in 0 minute (P less than 0.001) and could still inhibit nociceptive response of the neurons (P less than 0.01). Compared with the EA control group, lesion of hindlimb areas of SM could obviously increase the effect of EA activating NRM neurons, but had no influence on the effect of EA inhibiting nociceptive responses. 3. After lesion of bilateral larger areas of SM, the effects of EA on 14 neurons in NRM did not show activation of NRM neurons, but EA could still inhibit their nociceptive responses of the neurons in 5-25 minutes (P less than 0.01).