Fig. 2.

Following various nociceptive insults, neurons in the DRG may increase expression of excitatory channels and receptors and decrease expression of inhibitory channels. Satellite cells increase expression of gap junctions, signs of activation, and release of cytokines and other excitatory agents. Sprouting can occur from postganglionic sympathetic efferent fibers, which stain for TH and/or intrinsic peptidergic neurons, which envelop some of the larger cell bodies. Immune cells frequently infiltrate the DRG and release a selection of pro-inflammatory cytokines and other agents. TH tyrosine hydroxylase, NPY neuropeptide Y, NE norepinephrine, TNF(r) tumor necrosis factor and its receptor, VGCC voltage-gated calcium channel, NaV sodium channel TRPV1