内吗啡肽在脊髓背角浅层的镇痛机制

Analgesic mechanism of endomorphin in the superficial laminae of the spinal dorsal horn

内吗啡肽 (EM)是 μ阿片受体 (MOR)的内源性配体。脊髓背角浅层 (Ⅰ ,Ⅱ层 )是阿片类物质调制外周伤害性信息的关键部位 ,其内含EM和MOR的结构很密集。在脊髓背角浅层 ,EM可以抑制初级传入末梢释放谷氨酸和P物质 ,增加中枢内源性镇痛系统的下行投射末梢在脊髓背角释放去甲肾上腺素和 5 羟色胺 ,抑制脊髓背角Ⅱ层 (胶状质 )兴奋性中间神经元释放神经活性物质。在脊髓背角浅层EM可能通过以上途径实现对外周伤害性信息传递的调制并发挥镇痛作用。

Endomorphin(EM) has been proposed to be the endogenous ligand for the μ-opiate receptor (MOR). Densely occupied with EM- and MOR-containing structures, the superficial laminae of the spinal dorsal horn play important roles in nociceptive modulation by the opioid-like substances. EM might take part in the modulation of nociceptive transmission through the following pathways: (1) inhibiting the releases of glutamate and substance P from primary afferent terminals; (2)increasing the release of noradrenaline and serotonin in the spinal dorsal horn from the descending terminals of the central endogenous pain control system; (3)inhibiting the release of excitatory neurotransmitters from interneurons in lamina Ⅱ(substantia gelatinosa)of the spinal dorsal horn. In the superficial laminae of the spinal dorsal horn, EM may exert its modulatory and antinociceptive effects on the peripheral noxious information transmission by these pathways.