Abstract
The cingulate bundle in acupuncture analgesia was investigated by lesion and stimulation experiments. The pain threshold of tail-flick test in rats was increased by acupuncture stimulation or by intraperitoneally injected 0.5 mg/kg morphine in acupuncture effective animals which showed a significant increase (P<0.05) in tail-flick latency by acupuncture stimulation.
Insertion electrode (0.4 mm in diameter) to caudate nucleus through cingulate bundle or just to cingulate bundle abolished acupuncture analgesia and morphine analgesia, while insertion electrode to the cortex above cingulate bundle did not abolish both kinds of analgesia. Lesion of septal nucleus by insertion electrode also abolish both kinds of analgesia.
Stimulation of septal nucleus caused analgesia which was abolished by intraperitoneally injected 1mg/kg naloxone. Periaqueduct central gray (PAG) stimulation-produced analgesia was abolished by lesion of cingulate bundle.
Since it was reported that evoked potential was induced in periaqueduct central gray, septal nucleus, cingulate bundle and hippocampus by acupuncture stimulation and that PAG lesion abolished acupuncture and morphine analgesia, the abolishment of both kinds of analgesia by lesion of cingulate bundle might be due to lesion of acupuncture afferent pathway through PAG and cingulate bundle. Morphine analgesia might be caused by this pathway.
