Min Zhuo
It is well known that pain and anxiety can enhance each other in both animals and humans. In case of chronic pain, patients often suffer anxiety and depression. Animal experiments provide important basic mechanisms for the interaction between chronic pain and anxiety. At cortical level, recent studies have consistently indicated that anterior cingulate cortex (ACC) and insular cortex (IC), two critical cortical regions for pain-related unpleasantness and suffering, are also involved in the process of emotional anxiety. At synaptic level, long-term potentiation (LTP), a key cellular mechanism for memory and chronic pain, has also been found to contribute to emotional anxiety in animal models of chronic pain. In a recent study published in Neuron by the group of Prof. Xu, it has been found that at subcortical level, anterior and posterior paraventricular nucleus of the thalamus (PVT) contribute to pain and anxiety through distinct projections to the basolateral amygdala (BLA) and central amygdala (CeA). In this review, I will first introduce the recent work by Prof Xu, and then discuss possible mechanisms at different levels for pain and anxiety in the condition of chronic pain, including chronic visceral pain. Some of medicines used in the current treatment will be analyzed, and potential future treatment for pain and anxiety in chronic pain conditions will be discussed.