Guilbaud G
Rev Neurol (Paris). 1986;142(4):291-6.
Recent anatomical, electrophysiological, neuropharmacological and behavioural studies have provided new elements for the understanding of the role of the thalamus in nociceptive and pain mechanism. Data presented here demonstrate that the thalamic ventrobasal complex (VB), which receives direct afferents from the spinothalamic tract in the rat and monkey, plays a role in the sensory-discriminatory component of pain in these two species. Apart from the electrophysiological aspect, we discuss the effects of analgesic compounds on neuronal responses observed at this level and modifications in a nociceptive reaction threshold after lesions of this structure in the non-anesthetized freely moving animal. Data obtained in the normal rat are compared with those obtained under the same experimental conditions in a clinical pain model: the arthritic rat. In these animals the capacity of the VB neurons to respond to somatic stimuli is profoundly modified, many of them being activated by moderate stimuli from inflamed joints (lateral pressure, movements). Spinal tracts transmitting messages from these joints appear to differ (at least in part) from those transmitting nociceptive messages in the normal rat. Finally, at similar doses, morphine is much more effective in these animals than in the normal rat. Results of these studies show that nociception and clinical pain are not always exactly dependent on the same systems.
最近的解剖学、电生理学、神经药理学及行为学研究为理解丘脑在伤害感受及疼痛机制中的作用提供了新的线索。本文提供的数据表明，丘脑腹侧基底复合体（VB）在大鼠和猴中直接接收来自脊髓丘脑束的传入纤维，在这两个物种的疼痛感觉辨别成分中发挥作用。除了电生理学方面，我们还讨论了镇痛化合物对在此水平观察到的神经元反应的影响，以及在未麻醉的自由活动动物中该结构损伤后伤害性反应阈值的变化。将正常大鼠获得的数据与在临床疼痛模型——关节炎大鼠——相同实验条件下获得的数据进行比较。在这些动物中，VB神经元对躯体刺激的反应能力发生了深刻改变，其中许多神经元被来自发炎关节的适度刺激（侧压、运动）激活。传递来自这些关节信息的脊髓通路似乎与正常大鼠中传递伤害性信息的通路不同（至少部分不同）。最后，在相似剂量下，吗啡在这些动物中比在正常大鼠中更有效。这些研究结果表明，伤害感受和临床疼痛并不总是完全依赖于相同的系统。
