[The influence of pyramidal tract pathway of sensorimotor cortex on the effects of acupuncture analgesia on NRM neurons].

The experiment was to study whether the effects of electroacupuncture (EA) on neurons in nucleus raphe magnus (NRM) were influenced after lesion of bilateral pyramidal tracts (PT) in the rats. Unit discharges of NRM were recorded extracellularly with glass microelectrodes, and their nociceptive responses were induced by train electro-stimulation of tail. It was researched only the neurons with excitory response to noxious stimulation of the tail. 1. The effects of bilateral 'Zusanli' acupoint on 31 NRM neurons were observed in control group. EA had a tendency to activate NRM neurons, but inhibited obviously nociceptive response of the neurons at 0-30 minutes (P < 0.01). The effects of EA of PT control group (PT exposed and kept intact) were recorded on 8 units in NRM. EA had a tendency to activate the neurons, but inhibited obviously nociceptive response of the neurons and decreased nociceptive response rate 25.3 +/- 8.7% at 0 minute (n = 8, P < 0.05) 3. EA after the PT lesion, it obviously inhibited nociceptive response of the neurons in NRM at 0-20 minutes (n = 9, P < 0.01-0.05). It inhibited nociceptive response of all the neurons and decreased nociceptive response rate 57.8 +/- 11.6% at 0 minute (P < 0.01). The effect was larger than the effect of EA of PT control group and increased 32.5% at 0 minute (P < 0.05) than this. It also increased the effect of EA activating the neurons than PT control group. The results suggest that SM may influence the effect of EA analgesia, which involves in both PT and extrapyramidal system (EPS).(ABSTRACT TRUNCATED AT 250 WORDS)