Chaouch A, Besson J M
Rev Neurol (Paris). 1986;142(3):173-200.
Due to the combination of multidisciplinary studies, the last fifteen years have seen a major step forward in our knowledge of nociception. At the peripheral level the role of A delta and C polymodal cutaneous nociceptors is relatively well demonstrated in animal as well as in man. The activation of these nociceptors probably results from both direct effects of the stimulus and indirect effects, mediated by the release of various chemicals. The specific roles of articular, muscular and visceral fine afferent fibers in nociception, is less well understood. Cutaneous A delta and/or C fibers terminate mainly in the superficial zones (laminae I and II outer) of the dorsal horn. The nature of the transmitter (s) released by nociceptive afferents is still unknown. Substance P has long been a candidate but the multiplicity of peptides revealed by immunohistochemical techniques and their coexistence on occasions in the same dorsal root ganglion cells question a unequivocal role of substance P. At the level of the dorsal horn of the spinal cord, nociceptive specific and nociceptive non-specific units have been described in laminae I, II, IV to VI. It is generally held that nociceptive specific neurons are mainly found in the superficial laminae which also contains nociceptive non specific cells. Convergence of cutaneous, muscular and visceral inputs on these neurons is indicative of a role of both cell types in referred pain where consideration must also be given to the possibility of dichotomizing afferent fibers serving cutaneous and visceral territories. The involvement of contralateral ascending pathways (spinothalamic and spinoreticular tracts) in the transmission of nociceptive messages toward supraspinal structures is well established while the role of ipsilateral ascending systems (spino-cervical and dorsal columns post-synaptic fibers) is still questioned. Both segmental and descending modulating controls are exerted at the spinal level. At segmental levels, the inhibitory action of large diameter cutaneous fibers is now well established. The action of fine fibers seems also to be inhibitory. Descending influences are exerted from the periaqueductal gray matter and the ventromedial medulla (mainly the nucleus raphe magnus). They are sustained by serotoninergic and noradrenergic mechanisms and they involve to a lesser extent the endogenous opioids. The physiological function of these descending systems is still sharply discussed.
由于多学科研究的结合，在过去十五年里，我们对痛觉的认识取得了重大进展。在周围水平，Aδ和C多模式皮肤伤害感受器在动物和人类中的作用得到了相对充分的证明。这些伤害感受器的激活可能是由刺激的直接作用和由各种化学物质释放介导的间接作用共同导致的。关节、肌肉和内脏细传入纤维在痛觉中的具体作用尚不太清楚。皮肤Aδ和/或C纤维主要终止于背角的浅层区域（I层和II层外层）。伤害性传入纤维释放的递质的性质仍然未知。P物质长期以来一直是候选递质，但免疫组织化学技术揭示的肽的多样性以及它们有时在同一背根神经节细胞中共存，使P物质的明确作用受到质疑。在脊髓背角水平，I层、II层、IV至VI层中已描述了伤害性特异性和伤害性非特异性神经元。一般认为，伤害性特异性神经元主要存在于浅层，其中也包含伤害性非特异性细胞。皮肤、肌肉和内脏输入在这些神经元上的汇聚表明这两种细胞类型在牵涉痛中都起作用，在这种情况下还必须考虑为皮肤和内脏区域服务的传入纤维二分的可能性。对侧上行通路（脊髓丘脑束和脊髓网状束）在向脊髓上结构传递伤害性信息中的作用已得到充分证实，而同侧上行系统（脊髓颈束和背柱突触后纤维）的作用仍受到质疑。节段性和下行调制控制都在脊髓水平发挥作用。在节段水平，大直径皮肤纤维的抑制作用现已得到充分证实。细纤维的作用似乎也是抑制性的。下行影响来自导水管周围灰质和延髓腹内侧（主要是中缝大核）。它们由5-羟色胺能和去甲肾上腺素能机制维持，并且在较小程度上涉及内源性阿片类物质。这些下行系统的生理功能仍在激烈讨论中。
