Neural Circuits Mediating Aversion to Noxious Stimuli

描述（来自摘要）：与其他感官形式相比， 视觉和听觉，疼痛，根据定义，在阈值时是不愉快的。这 不愉快是逃避和逃避的主观关联 组织损伤刺激。虽然临床的重要性， 痛苦的情感动机方面是普遍接受的，缺乏一个 有效的动物模型阻碍了对其神经生物学基础的研究。的 本项目提出的研究是专门设计来研究 由伤害性刺激引起的厌恶的神经机制。调查人员 将调整位置偏好装置来测量厌恶的程度 与后爪福尔马林注射相关的背景（条件位置 厌恶或CPA）。大鼠将在一个有明显 嗅觉、视觉和触觉提示。每隔一天，他们将接受生理盐水 在第二隔间中。福尔马林处理后， 在福尔马林相关隔室中消耗的时间将被视为 厌恶福尔马林诱发CPA对多种中枢神经系统的失活作用 将研究与伤害感受有关的结构。在最初的实验中， 老鼠将接受一种P物质受体神经毒素， β-皂草素结合物，在腰椎鞘内空间选择性破坏 脊髓中脑和脊髓丘脑神经元。如果这降低了CPA， 将测试大鼠的损伤或暂时失活的影响， 臂旁核和脊髓丘脑靶核和皮质区 被有害刺激激活拟研究的丘脑区包括 腹基底复合体、后丘脑/后椎板内组和 中间丘脑/板内区域。待研究的皮层区域 包括躯体感觉、前扣带和颗粒异常岛叶皮质。 在补充研究中，通过失活而与厌恶有关的皮层区域 研究将使用兴奋性化学试剂刺激，以确定是否 局部神经元活动可以在缺乏外周伤害性刺激的情况下诱发CPA。 刺激。最后，他们将研究甲醛行为和CPA的影响， 下行调节系统的可逆失活。

DESCRIPTION (from abstract): In contrast to other sensory modalities such as vision and hearing, pain is, by definition, unpleasant at threshold. This unpleasantness is the subjective correlate of a drive to escape and avoid tissue damaging stimuli. Although the clinical importance of the affective-motivational aspect of pain is generally accepted, the lack of a valid animal model has hampered investigation of its neurobiological basis. The research proposed in this project is specifically designed to examine the neural mechanisms of aversion produced by noxious stimuli. The investigators will adapt the place preference apparatus to measure the magnitude of aversion to a context associated with hindpaw formalin injection (condition place aversion or CPA). Rats will receive formalin in a compartment with obvious olfactory, visual and tactile cues. On alternate days they will receive saline in a second compartment. After formalin conditioning, the reduction of time spent in the formalin-associated compartment will be taken as a measure of aversiveness. The effects on formalin elicited CPA of inactivating various CNS structures implicated in nociception will be studied. In the first experiments, rats will receive a substance P receptor neurotoxin, the substance P-saporin-conjugate, in the lumbar intrathecal space to selectively destroy lamina I spinomesencephalic and spinothalamic neurons. If this reduces CPA, rats will be tested for the effects of lesions or transient inactivation of the parabrachial nucleus and of spinothalamic target nuclei and cortical areas activated by noxious stimuli. Thalamic areas to be studied include the ventrobasal complex, the posterior thalamic/posterior intralaminar group and the media thalamic/intralaminar region. The cortical areas to be studied include the somatosensory, anterior cingulate and dysgranular insular cortices. In complementary studies, cortical areas implicated in aversion by inactivation studies will be stimulated using excitatory chemical agents to determine if local neuronal activity can elicit CPA in the absence of a peripheral noxious stimulus. Finally, they will study the effect on formalin behaviors and CPA of reversible inactivation of descending modulatory systems.