Research progress on neural circuit mechanisms of acupuncture intervention in pain-related emotions

The occurrence and development of pain-related emotions are closely associated with structural and functional alterations in central neural circuits. Acupuncture can effectively alleviate pain-related emotions and reduce pain-associated negative emotions such as anxiety, depression and pain-aversive memory, and its mechanism is tightly correlated with the regulatory effect of acupuncture on the functions of specific neural circuits. This article sorts out the pain-related emotion-associated neural circuits modulated by acupuncture, and summarizes the relevant circuits as follows: the anxiety-related circuits include rostral anterior cingulate cortex glutamatergic neurons → thalamus (rACC^Glu→Th), rostral anterior cingulate cortex glutamatergic neurons → dorsal raphe nucleus (rACC^Glu→DRN), rostral anterior cingulate cortex glutamatergic neurons → ventrolateral periaqueductal gray (rACC^Glu→vlPAG), basolateral amygdala CaMKⅡ neurons → rostral anterior cingulate cortex (BLA^CaMKⅡ→rACC), and ventral tegmental area dopaminergic neurons → nucleus accumbens (VTA^DA→NAc); the depression-related circuit is infralimbic cortex CaMKⅡα⁺ neurons → basolateral amygdala (IL^CaMKⅡα+→BLA); the circuit related to pain-aversive memory and reward is infralimbic cortex glutamatergic neurons → nucleus accumbens (IL^Glu→NAc). Among these, acupuncture may exert analgesic and anxiolytic effects by inhibiting the rACC^Glu→Th and rACC^Glu→vlPAG circuits, and activating the rACC^Glu→DRN, BLA^CaMKⅡ→rACC and VTA^DA→NAc circuits; produce analgesic and antidepressant effects by suppressing the IL^CaMKⅡα+→BLA circuit; and achieve analgesic effects as well as regulate pain-aversive memory and reward by activating the IL^Glu→NAc circuit. This review provides a reference for the research and application of neural circuit mechanisms underlying acupuncture treatment of pain-related emotions.