健康与遗传心理学研究室知识库

 
疼痛包含感觉-辨别和情绪-动机两个维度。虽然疼痛感觉成分的传导通路已经得到广泛研究，目前疼痛情绪成分的机制还需要进一步探索。近年来，条件位置厌恶（CPA）范式已经被用于研究疼痛的情绪成分。前人的研究在动物和人类身上均发现了前额皮层参与疼痛情绪的调控，因此本研究使用福尔马林建立的条件位置厌恶（F-CPA）范式探索前额皮层的两个亚区前边缘皮层（PL）和下边缘皮层（IL）在 F-CPA 习得和表达中的作用。本研究共使用77 只雄性 SD大鼠。大鼠在埋管手术恢复后接受 F-CPA训练，在一侧条件化箱给予大鼠后爪足底皮下注射福尔马林（5％，50μL），而另一侧箱子内不给予任何处理。为了检测 PL 或IL暂时失活对 F-CPA  习得和表达的影响，分别在福尔马林配对训练或测试前向双侧 PL 或 IL 内注射 GABAA 受体激动剂蝇蕈醇（0.9％氯化钠，0.55 nmol/μL，0.2μL/侧），同时记录了蝇蕈醇给药后福尔马林诱发的伤害性舔脚行为和运动距离。结果表明，PL 失活阻碍了 F-CPA的习得和表达，而 IL 失活并没有影响。此外，PL 或 IL 失活均没有影响福尔马林诱发的伤害性舔脚行为或自发运动距离，这说明 F-CPA学习受损并不是由于大鼠痛感知或运动性的降低。所以，这些研究结果表明了 PL 在疼痛情绪加工中的重要作用。 

Pain has sensory-discriminative and emotional-motivative components. Although the pathways of the sensory component of pain have been extensively investigated, the mechanisms underlying the affective component of pain need to be further explored. In recent years, conditioned place avoidance (CPA) paradigm has been used to investigate the affective component of pain. Animal and human studies have indicated prefrontal cortex is involved in the modulation of pain emotion. Thus, the present study investigated the role of prefrontal subdivisions, prelimbic cortex (PL) and infralimbic cortex (IL), in the acquisition and expression of formalin-induced CPA (F-CPA). Seventy-seven male Sprague-Dawley rats were included in our study. After recovery from cannula implantation surgery, rats underwent the F-CPA training, with hindpaw intraplantar injection of formalin (5%, 50 μl) in one conditioning chamber and no treatment in the other. GABAA receptor agonist muscimol (0.9% NaCl, 0.55 nmol/μL, 0.2  μL/side) was bilaterally infused into PL or IL before the formalin-paired training or test to explore the effect of PL or IL temporary inactivation on the acquisition and expression of F-CPA respectively. Formalin-induced licking behavior and locomotor distance after muscimol infusion were also measured. The results showed that inactivation of PL but not IL prevented acquisition and expression of F-CPA. Moreover, inactivation of neither of them had effect on formalin-induced nociceptive behavior or locomotor distance, suggesting the impaired learning of F-CPA was not due to reduced sensory pain perception or locomotor activity. These findings demonstrated the important role of PL rather than IL in the acquisition as well as expression of F-CPA.