Abstract:Objective:To analyze the antinociceptive effect of red nucleus (RN) and the involved mechanism. Methods:The single units of wide dynamic range (WDR) neurons in the spinal cord dorsal horn were recorded extracelluarly. The effects of RN stimulation on nociceptive responses (C-fibres-evoked responses, C-responses) of WDR neurons were observed. Results: 1. Stimulation in RN caused a significant reduction of nociceptive response of WDR neurons. 2.The effect of RN stimulation on contralateral WDR neurons was more powerful than that on ipsilateral WDR neuron. 3. The inhibitory effect produced by RN stimulation was not reversed by intravenous naloxone. Conclusion:The results suggested that RN might be involved in the antinociception in a naloxone-nonreversible manner.