Table 1.

Possible pathways through which acupuncture analgesia alleviates central sensitization.

Mechanism	Related part of neuron/nucleus
(1) Segmental inhibition	dorsal horn
(2) Endogenous opioid pathway	dorsal horn, PAG, NRM, dorsal raphe nucleus
(3) Adrenergic pathway	dorsal horn, PAG, raphe nuclei, locus coeruleus and brainstem (A1, A2, A4-7 nuclei), forebrain
(4) 5-Hydroxytryptamine pathway	NRM, RVM, trigeminal nucleus caudalis
(5) NDMA pathway	dorsal horn
(6) Local inflammatory environment	nerve ending, dorsal horn

NMDA: N-methyl-D-aspartic acid; PAG: periaqueductal gray; NRM: nucleus raphe magnus; RVM: rostral ventromedial medulla.