“…Glial cells, which receive information from both primary afferent terminals and pain transmission neurons, can be sensitively activated by a wide array of substances, such as excitatory amino acids, nitric oxide, prostaglandins, tissue/nerve injury, and pathogens (Cury et al, ; Ji et al, ; Mika et al, ; Bobba et al, ; Martini and Willison, ; Old et al, ; Ni et al, ). The microglia and astrocytes respond to increased input from the periphery by producing and secreting diverse pronociceptive mediators, such as cytokines, chemokines, and ATP (Jha et al, ; Old et al, ).…”