Abstract:The experiments were conducted on 23 anesthetized rats. The single unit activity was recorded extracellularly from thalamic nucleus submedius (Sm) with a glass micropipette, and the responses of neurons in Sm to acupuncture were observed. The results showed that most of the neurons in Sm resPOnded to needle acupuncture. In general the neurons which responded to needle acupuncture also responded to noxious cutaneous or muscle stimuli, suggesting that the properties of the needle acupuncture are similar to those of the noxious mechanical stimulation. The Sm probably plays an important role in the formation of the needling sensation and the central mechanism of acpuncture analgesia. Results of this study provide support for the assumption that the spinal cord-Sm-VLO(ventral lateral orbital cortex)-PAG-spinal cord negative feedback circuit for nociceptive modulation participates in the acupuncture analgesia, especially in that produced by activation of the small afferent fibers.
