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 （rACCGlu→Th）， rostral anterior cingulate cortex glutamatergic neurons → dorsal raphe nucleus （rACCGlu→DRN）， rostral anterior cingulate cortex glutamatergic neurons → ventrolateral periaqueductal gray （rACCGlu→vlPAG）， basolateral amygdala CaMKⅡ neurons → rostral anterior cingulate cortex （BLACaMKⅡ→rACC）， and ventral tegmental area dopaminergic neurons → nucleus accumbens （VTADA→NAc）； the depression-related circuit is infralimbic cortex CaMKⅡα+ neurons → basolateral amygdala （ILCaMKⅡα+→BLA）； the circuit related to pain-aversive memory and reward is infralimbic cortex glutamatergic neurons → nucleus accumbens（ILGlu→NAc）. Among these， acupuncture may exert analgesic and anxiolytic effects by inhibiting the rACCGlu→Th and rACCGlu→vlPAG circuits， and activating the rACCGlu→DRN， BLACaMKⅡ→rACC and VTADA→NAc circuits； produce analgesic and antidepressant effects by suppressing the ILCaMKⅡα+→BLA circuit； and achieve analgesic effects as well as regulate pain-aversive memory and reward by activating the ILGlu→NAc circuit. This review provides a reference for the research and application of neural circuit mechanisms underlying acupuncture treatment of pain-related emotions.