Corticofugal outputs facilitate acute, but inhibit chronic pain in rats
Corticofugal outputs facilitate acute, but inhibit chronic pain in rats
复制标题
离皮质输出促进大鼠急性疼痛，但抑制慢性疼痛
DOI：
10.1016/j.pain.2008.12.016
复制
发表时间：
2009-03-01
期刊：
影响因子：
7.4
通讯作者：
Luo, Fei
中科院分区：
文献类型：
--
作者：
Wang, Ning;Wang, Jin-Yan;Luo, Fei
初级躯体感觉皮层（SI）在痛觉的感觉辨别方面起着重要的作用，这一点已被广泛接受。然而，目前尚不清楚SI是否在疼痛的下行调制中发挥作用。虽然有丰富的纤维从感觉皮层投射回丘脑核团，和皮质调制的影响，从SI丘脑伤害性中继神经元已被解决，很少有人知道皮质输出如何调节伤害性行为所造成的组织损伤或引起的疼痛刺激。本研究采用伤害性热致急性痛、福尔马林致急性炎性痛和CFA致慢性炎性痛大鼠模型，探讨皮层输出是否影响伤害性行为。结果表明，皮质内微量注射GABA（A）激动剂蝇蕈醇可显著降低福尔马林实验的第一和第二相行为，并提高热刺激引起的急性疼痛的伤害性感受阈值，表明SI对急性疼痛感觉具有易化作用。与此相反，微量注射GABA（A）拮抗剂荷包牡丹碱显着降低CFA发炎后爪的热痛觉过敏，表明在慢性疼痛状态下SI输出的抑制作用。在急性和慢性疼痛状态下的相反调节作用表明，在疼痛疾病的不同阶段，SI皮层存在功能开关，这对生物适应具有重要意义。(C)2008年国际疼痛研究协会。Elsevier B.V.出版，保留所有权利。
It has been widely accepted that the primary somatosensory cortex (SI) plays an essential role in the sensory-discriminative aspect of pain perception. However, it remains unclear whether the SI has a role in the descending modulation of pain. Although there are abundant fibers projecting back from sensory cortex to thalamic nuclei, and the influence of cortical modulation from SI on the thalamic nociceptive relay neurons has been addressed, little is known about how the cortical outputs modulate the nociceptive behaviors resulting from tissue injury or evoked by painful stimulation. The present study was designed to test whether the cortical outputs influenced the nociceptive behaviors using rat models of noxious thermal-induced acute pain, formalin-induced acute and CFA-evoked chronic inflammatory pain. The results showed that intracortical microinjection of GABA(A) agonist muscimol significantly reduced the first and second phase behaviors in formalin tests and elevated the nociceptive thresholds in the thermal stimulus-elicited acute pain, suggesting a facilitatory influence of SI on the acute pain sensation. By contrast, microinjection of GABA(A) antagonist bicuculline remarkably reduced the thermal hyperalgesia of the CFA-inflamed hindpaws, indicating an inhibitory effect of SI output in the chronic pain state. The opposite modulatory effects in acute and chronic pain states suggest that there exists a functional switch for the SI cortex at different stages of pain disease, which is of great significance for the biological adaptation. (C) 2008 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.