Abstract
Noradrenergic (NAergic) neurons in the locus coeruleus (LC) have been implicated in fear, anxiety, arousal, and stress. In addition, LC‐NAergic neurons are activated by peripheral noxious stimulation. These neurons project their axons to the brain regions but also to the spinal dorsal horn (SDH) , and it is believed that spinal NA suppresses pain transmission. Like the brain, numerous glial cells are present in the SDH. We have recently identified a subset of astrocytes localized in the superficial SDH and found that in response to noxious stimulation to the skin, this subset induces a rise in intracellular calcium levels. The astrocytic responses were mediated by signals from the descending LC‐NAergic neurons, resulting in causing behavioral hypersensitivity to light mechanical stimuli. This review describes the new astrocyte‐mediated regulatory mechanism in descending noradrenergic pain control.
