Functional significance of nociceptive amygdala in pain-induced negative emotion

脊髓背角上的大多数伤害感受特异性突起神经元投射到外侧臂旁核（LPB），而外侧臂旁核又投射到中央杏仁核（CeC）的荚膜部分，这为伤害感受与情绪之间的直接联系奠定了解剖学基础。本研究旨在探讨慢性疼痛模型中LPB-CeC传递增强的机制及其生理意义。我们分析了脊髓神经结扎和链脲霉素诱导的糖尿病患者急性神经性疼痛模型的脑切片中LPB-CeC的传递以及其他杏仁核亚核内的传递。单囊泡含量、单纤维释放和不同释放概率下的振幅波动的估计明确表明，释放位点数量的增加允许多个囊泡从增强突触的单纤维末端同步释放。这些结果指出了慢性神经性疼痛中杏仁核突触的特定结构可塑性及其巩固，为伤害感觉与负面情绪之间的联系增强提供了依据。

The majority of nociception-specific projecting neurons in the spinal dorsal horn project to the lateral parabrachial nucleus(LPB) that in turn project to the capsular part of the central amygdala(CeC), forming an anatomical basis for direct link between nociception and emotion. The aim of this study was to identify the mechanism and physiological significance of the potentiated LPB-CeC transmission in chronic pain models. We analyzed the LPB-CeC transmission as well as those within other amygdaloid subnuclei in acutely prepared brain slices prepared from neuropathic pain models by spinal nerve ligation and streptozocin-induced diabetics. Estimation of mono-vesicular content, single fiber release and amplitude fluctuation at different release probabilities unequivocally demonstrated an increased number of release sites allowing multiple vesicles to be released in synchrony from single fiber terminals in potentiated synapses. These results point to a specific structural plasticity and its consolidation in the amygdala synapses in the chronic neuropathic pain, which would provide basis for the enhanced link between nociception and negative emotion.