[Research progress of acupuncture in improving pain emotion by regulating functions of anterior cingulate cortex]

Pain emotion is a negative emotion caused by pain, which seriously affects the patients' physical and psychological health. The anterior cingulate cortex (ACC) is a key brain region in the occurrence and regulation of pain and painful emotion. In this paper, we summed up the relevant progress of researches on acupuncture improvement of pain emotion from neurotransmitters and receptors, cellular signaling pathways and neural circuits of ACC, in order to provide a basis for further research. 1) Acupuncture can regulate the long-term potentiation of ACC synaptic transmission by down-regulating the expression of N-methyl-D-aspartic acid receptor (NMDAR)； and up-regulating the expression of μ-, delta- and κ-opioid receptors, neuropeptide S (NPS)/ NPS receptor, and the number of parvalbumin-expressing interneurons to reduce neuronal excitability, relieving pain emotion； 2) Acupuncture can regulate synaptic transmission of ACC neurons by inhibiting protein kinase Mζ (PKMζ)-GluR1 and cAMP/PKA-ERK-CREB signaling pathways, and modulate synaptic plasticity to ameliorate pain emotion； 3) Acupuncture intervention induced inhibition of rostral ACC^Glu-thalamic circuit may result in relief of pain emotion but not pain sensation, whereas inhibition of the rostral ACC^Glu-ventrolateral periaqueductal gray matter(vlPAG) circuit may relieve pain sensation but not pain emotion. In addition, our team found that in the treatment of painful diseases by acupuncture, the addition of "spirit-regulating" acupoints can not only improve patients' negative emotion, but also significantly relive patients' pain sensation.