“Neuroinflammation” is largely used as a synonym of microglia and astrocyte reactivity, particularly microglia activation/reaction—any reaction; the highly specialized nature of microglia in the CNS and microglia molecular and phenotypic heterogeneity are ignored; the detection of “inflammatory cytokines” in CNS tissues or fluids is considered a sign of “neuroinflammation”; and “neuroinflammation” is essentially always considered pathological and frequently labeled a cornerstone of neurological disorders. (Galea & Graeber, 2023)
Afferent nerve fibers carrying pain information are responsible for peripheral sensitization partly linked to inflammation molecules. These afferent fibers release neurotransmitters in the dorsal root ganglion and dorsal horn of the spinal cord, capable of activating microglia, which are the local immune cells. The activated microglia will produce pro-inflammatory cytokines, chemokines and neuropeptides capable of interacting with the second-order neuron, but also segmental and descending inhibitory neurons. This is referred to as neuroinflammation, which will amplify the hypersensitivity of second-order neurons, otherwise called central sensitization. (Vergne & Bertin, 2021)
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