Reflex-related activation of putative pain facilitating neurons in rostral ventromedial medulla requires excitatory amino acid transmission
Reflex-related activation of putative pain facilitating neurons in rostral ventromedial medulla requires excitatory amino acid transmission
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DOI：
10.1016/s0306-4522(96)00683-5
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发表时间：
1997-06-01
期刊：
影响因子：
3.3
通讯作者：
Roychowdhury, SM
中科院分区：
文献类型：
--
作者：
Heinricher, MM;Roychowdhury, SM
虽然吻侧腹内侧髓质在疼痛调节中的重要性已被普遍接受，但认识到它可以发挥疼痛促进和疼痛抑制的影响，其组成的神经元群在生理和药理学上是不同的，这是相对较新的。在电生理实验中发现了一类神经元，它可能是促进髓质吻侧腹内侧影响的来源。这些神经元被称为“上细胞”，其特征是在恶意反射之前突然爆发活动。这种放电被认为是生理条件下脑干控制伤害性传递的一个重要因素。本研究的目的是确定一种兴奋性氨基酸是否参与了反射相关的爆发的产生，这种爆发定义了细胞上的，以及更广泛的；探讨兴奋性氨基酸神经递质在大鼠鼻侧腹内侧髓质的作用。离子电泳应用广谱兴奋性氨基酸受体拮抗剂kynurenate可显著减少反射相关的细胞内爆发，而持续的放电不受影响。其他髓质神经元的自发活动没有变化。这些数据表明，内源性兴奋性氨基酸神经递质的释放对于激活与有害反射相关的细胞是必要的。相比之下，在轻度麻醉大鼠中，这些受体在维持吻侧腹内侧髓质的任何细胞类别的持续活动中明显发挥的作用要小得多。(c) 1997年。Elsevier Science Ltd.出版。
Although the importance of the rostral ventromedial medulla in pain modulation is generally accepted, the recognition that it can exert both pain facilitating and pain inhibiting influences, and that its constituent neuronal population is physiologically and pharmacologically heterogeneous, is relatively recent. A class of neuron which may be a source of facilitating influences from the rostral ventromedial medulla has been identified in electrophysiological experiments. These neurons, termed ''on-cells,'' are characterized by a sudden burst of activity beginning just before nocifensive reflexes. This burst of firing is thought to be a significant factor in brainstem control of nociceptive transmission under physiological conditions. The aim of the present study was to determine whether an excitatory amino acid is involved in generation of the reflex-related burst that defines on-cells, and more generally; to examine the role of excitatory amino acid neurotransmitters within the rostral ventromedial medulla of the rat. Iontophoretic application of the broad-spectrum excitatory amino acid receptor antagonist kynurenate significantly reduced the reflex-related on-cell burst, whereas ongoing firing was unaffected. Spontaneous activity of other medullary neurons was unchanged.These data demonstrate that release of an endogenous excitatory amino acid neurotransmitter is necessary for the activation of on-cells that is associated with nocifensive reflexes. In contrast, these receptors evidently play a much less significant role in maintaining the ongoing activity of any cell class in the rostral ventromedial medulla in lightly anaesthetized rats. (C) 1997 IBRO. Published by Elsevier Science Ltd.