[The analgesic effect of red nucleus and strengthening effect thereof to the acupuncture analgesia].

The modulation of red nucleus (RN) to pain sense was researched with the latent period of radiant-heat tail flick of rats as standard of the pain threshold. The pain threshold of tail flick reflex was raised significantly by bilateral injection of glutamic acid into RN. Simultaneous injecting glutamic acid into RN and lidocaine into nucleus raphe magnus (NRM) could attenuate the raising effect of pain threshold of RN. This showed that the activated RN has analgesic effect and the NRM plays an important role in the descending inhibitory pathway of RN. The discharges of neurons in caudal part of nucleus spinalis tract nervi trigemini (cNST) evoked by stimulating nerve alveolaris inferior (nAI) with strong pulse were recorded with microelectrode. The nAI-evoked discharges might be inhibited by stimulating contralateral or ipsilateral RN. The RN inhibitory time course on nAI-evoked discharges were shortened after injecting lidocaine into NRM. This demonstrated that the inhibitory effect of RN on neurons in cNST is mediated by NRM. The electrical stimulation of acupoint "Jiache" could inhibit the pain-evoked discharges of neurons in cNST. The inhibitory time course of electrical acupuncture were prolonged by stimulating RN. This result revealed that the activated RN can strengthen the analgesic effect of acupuncture.