A wide array of chemical mediators are produced in the the PNS and have both
excitatory and inhibitory influences on peripheral sensory nerve
transmission4 both in the acute and chronic phase of
injury (Figure 9–3)5. These can directly
activate the nerve (ATP, glutamate, 5-hydroxytryptamine [5-HT], histamine,
bradykinin), enhance depolarization by sensitizing the nerve to other
stimuli (prostaglandins, prostacyclin, and cytokines such as interleukins)
or provide a regulatory role on the sensory neuron, inflammatory cells, and
sympathetic fibers (bradykinin, tachykinin, and nerve growth factor).