刺激中缝背核对大鼠脊髓背角神经元伤害性反应的影响及其传出途径的分析

大量资料表明,中缝背核(DR)在痛觉调节中具有重要作用。本实验用电生理学方法研究DR在痛觉调制中的下行性抑制作用,主要观察刺激DR对清醒制动大鼠脊髓背角神经元伤害性放电的影响。其主要结果是:①刺激DR或电针可以抑制脊髓背角神经元的伤害性反应,吗啡可加强这种抑制效应;②损毁中缝大核(NRM)、纳洛酮、麦角酰二乙胺(LSD)、赛庚啶及对氯苯丙氨酸(PCPA)均能部分阻断DR对脊髓背角神经元伤害性反应的抑制,实验结果表明:刺激DR抑制脊髓背角神经元的伤害性反应,部分是通过NRM间接控制背角神经元的伤害性传入;还有一部分是不通过NRM,可能是DR直接对脊髓背角伤害性信息的调制。在这种下行性抑制通路中有5-HT和阿片样物质的参与。

EFFECT OF DORSAL RAPHE NUCLEUS STIMULATION ON NOCICEPTIVE RESPONSE OF DORSAL HORN NEURONS AND EFFERENT PATHWAY ANALYSIS IN RATS

A lot of data have demonstrated that the dorsal raphe nucleus (DR) playsan important role in pain modulation. In the present experiment the descendinginhibition from DR stimulation in pain modulation was investigated. The effectsof DR stimulation on the nociceptive discharges of spinal dorsal horn neurons wereexamined in immobilized rats. The main results werce (1) DR stimulation andelectroacupuncture induced significantly inhibitory effects on nociceptive responsesof dorsal horn neurons, and this inhibition was enhanced by morphine; (2) Theinhibitory effect induced by DR stimulation could be partially reversed by destructionof nucleus raphe magnus (NRM) and by injection of naloxone, lysergic acid diethy-lamide, cyproheptadine or p-chlorophenylalanine. It is suggested that the in-hibition of the nociceptive responses of spinal dorsal horn neurons by DR stimulationmight be partly achieved via the indirect control of NRM on the nociceptive afferentof spinal dorsal horn neurons, and partly mediated by direct modulation of DR onspinal nociceptive messages. Serotonin and opioid-like substance might be involvedin this inhibition.