Inflammatory Changes in Paravertebral Sympathetic Ganglia in Two Rat Pain Models

Schematic diagram of lumbar sympathetic system. Sympathetic preganglionic neurons (red) have cell bodies in the intermediolateral cell columns of the spinal cord. Their axons leave the cord through the ventral roots (VR) and follow white rami (WR) to the paravertebral sympathetic ganglion (SG) chain. Some make synapses with postganglionic neurons (green) in the paravertebral SGs, either at the same level, or at other levels after projecting in the sympathetic chain. Axons of some preganglionic neurons pass through chain ganglia without synapsing and connect with postganglionic neurons in prevertebral or pelvic ganglia. At the level of the L5 DRG there are no white rami, as preganglionic neurons are found in more rostral regions. Here, postganglionic axons primarily from SG neurons in SG3 (not shown) or SG4 run through the gray ramus (GR) to the L5 spinal nerve, where they may project along the ventral ramus (vr) of the spinal nerve to enter the sciatic nerve and reach peripheral targets, or project into the dorsal ramus (dr) of the spinal nerve, or innervate the region around the L5 DRG itself (primarily innervating blood vessels in normal animals)