Burnstock G
Autonomic Neuroscience Institute, Royal Free and University College Medical School, London, UK.
Br J Anaesth. 2000 Apr;84(4):476-88. doi: 10.1093/oxfordjournals.bja.a013473.
P2X receptors are a family of ligand-gated ion channels responsive to ATP. Seven subtypes have been identified which form homo-multimeric or hetero-multimeric pores. P2X3 receptors are selectively expressed predominantly on small-diameter nociceptive sensory neurones in the dorsal root, trigeminal and nodose ganglia, particularly the non-peptidergic subpopulations labelled with the lectin IB4. P2X2/3 labelling is also present in inner lamina II of the spinal cord and in sensory nerve projections to skin and viscera, but few receptors are present in skeletal muscle. P2X3 receptors are down-regulated after peripheral nerve injury and their expression can be regulated by glial cell-derived neurotrophic factor. P2X receptor activation of sensory neurones has been demonstrated in in vivo pain models, including the rat hindpaw and knee-joint preparations, as well as in inflammatory models. P2X4 and/or P2X6 receptors in the CNS also seem to be involved in pain pathways. Non-nociceptive P2 receptors on sensory nerves are present in muscle and on sensory endings in the heart and lung that initiate reflex activity involving vagal afferent and efferent nerve fibres. The sources of ATP involved in nociception and non-nociceptive sensory nerve stimulation are discussed as well as a novel hypothesis about purinergic mechanosensory transduction.
P2X受体是一类对ATP有反应的配体门控离子通道家族。已鉴定出七种亚型，它们形成同源多聚体或异源多聚体孔道。P2X3受体主要选择性地表达于背根神经节、三叉神经节和结状神经节中的小直径伤害性感觉神经元上，特别是那些用凝集素IB4标记的非肽能亚群。脊髓板层II内层以及向皮肤和内脏的感觉神经投射中也存在P2X2/3标记，但骨骼肌中几乎没有受体。外周神经损伤后P2X3受体下调，其表达可受胶质细胞源性神经营养因子调节。在包括大鼠后爪和膝关节制备物在内的体内疼痛模型以及炎症模型中，已证实感觉神经元的P2X受体激活。中枢神经系统中的P2X4和/或P2X6受体似乎也参与疼痛通路。感觉神经上的非伤害性P2受体存在于肌肉以及心脏和肺部的感觉末梢，这些部位启动涉及迷走传入和传出神经纤维的反射活动。文中还讨论了参与伤害感受和非伤害性感觉神经刺激的ATP来源以及关于嘌呤能机械感觉转导的新假说。
