Question

What signal(s) cause the development of the sensory neurons in the dorsal root ganglia?

Answer 1

Dorsal root ganglion (DRG) is a cluster of neurons in dorsal root of spinal nerve which carry sensory nerve signals to CNS from PNS. It consist of a group of cell bodies for the transmission of sensory messages from different receptors like thermoreceptors, nociceptor, proprioreceptor and chemoreceptors to the CNS. It actively participate in peripheral processes which includes PAF injury, inflammation, neuropathic pain development, etc. Dorsal root ganglion possess pseudounipolar neurons with a cell body which bifurcates into two branches that acts as a single axon. Action potentials generated at the periphery may bypass the dorsal root ganglion and continue through to the proximal process and spinal cord.

The sensory nervous system's response to harmful stimuli (nociception) signaling pathway stimulate the sensory neurons of DRG which acts through G-protein coupled receptors. The nerve endings of dorsal root ganglion neurons contains variety of sensory receptors which are activated by mechanical, chemical, thermal and harmful stimuli. Action potentials are generated via DRG neurons stimulated by mechanical stimuli by means of somatosensory transduction in the ion channels present in those sensory neurons. Two strech gated ion channels are operational in the posterior root ganglion neurons namely high threshold and low threshold. The former has a role in nociception and are activated by high pressures and due to nociceptors. The presynaptic contol over pain and nociception signals via GABAA receptors also indicate DRG's clinical significance.