How could central pain occur in the absence of peripheral tissue injury?
Neurons can become more readily depolarized and hence more sensitive because of a number of cellular changes.
These include sustained exposure to excitatory transmitters like glutamate and substance P.
Such activity may recruit cytokines, prostaglandins, and other inflammatory mediators.
Activation of kinases promotes phosphorylation that may change the susceptibility of ion channels to depolarizing current and trigger a cascade to intracellular changes including the production of more sodium or calcium channels.