Unexplained peculiarities of the dorsal root ganglion

The cell soma of primary afferent neurons in the dorsal root ganglion (DRG) is assigned by classical neurophysiology the role of a metabolic depot, charged with supporting the peripheral sensory ending, the conducting axon, and the central synaptic terminals. However, certain peculiarities of DRG morphology and physiology do not sit well with this being its only role. For example, why are DRG cell somata electrically excitable, why are some able to fire repetitively on sustained depolarization, and why does the DRG lack a blood-nerve barrier? Consideration of these and related questions leads to several intriguing hypotheses: (1) Electrical excitability of the soma may be required to insure the reliable propagation of impulses past the DRG T-junction and into the spinal cord. (2) Invasion of the afferent spike into the cell soma may provide an essential feedback signal necessary for the cell soma to regulate the excitability of the sensory ending. 3) The subpopulation of DRG neurons that have repetitive firing capability may be responsible for generating the background sensation that we feel as our body schema. Moreover, these neurons may be chemical sensors that provide essential information about our body's internal milieu.

[1]  D. N. Landon Peripheral Nerve , 2020, Congress of Neurological Surgeons Essent.

[2]  M. Devor,et al.  Modulation of activity in dorsal root ganglion neurons by sympathetic activation in nerve-injured rats. , 1994, Journal of neurophysiology.

[3]  K. Burchiel Spontaneous impulse generation in normal and denervated dorsal root ganglia: Sensitivity to alpha-adrenergic stimulation and hypoxia , 1984, Experimental Neurology.

[4]  S. Dib-Hajj,et al.  SNS Na+ channel expression increases in dorsal root ganglion neurons in the carrageenan inflammatory pain model , 1998, Neuroreport.

[5]  C. Lüscher,et al.  Action potential propagation through embryonic dorsal root ganglion cells in culture. II. Decrease of conduction reliability during repetitive stimulation. , 1994, Journal of neurophysiology.

[6]  D. Julius,et al.  The capsaicin receptor: a heat-activated ion channel in the pain pathway , 1997, Nature.

[7]  M. Devor,et al.  Na+ conductance and the threshold for repetitive neuronal firing , 1992, Brain Research.

[8]  P. E. Pannese,et al.  The Satellite Cells of the Sensory Ganglia , 1981, Advances in Anatomy Embryology and Cell Biology.

[9]  M. Devor,et al.  Mutual excitation among dorsal root ganglion neurons in the rat , 1992, Neuroscience Letters.

[10]  W. Catterall,et al.  Biosynthesis and processing of the α subunit of the voltage-sensitive sodium channel in rat brain neurons , 1986, Cell.

[11]  Steven F. Maier,et al.  Immune activation: the role of pro-inflammatory cytokines in inflammation, illness responses and pathological pain states , 1995, Pain.

[12]  M. Devor,et al.  Effect of age and nerve injury on cross-excitation among sensory neurons in rat dorsal root ganglia , 1999, Neuroscience Letters.

[13]  P. D. Wall,et al.  Sensory afferent impulses originate from dorsal root ganglia as well as from the periphery in normal and nerve injured rats , 1983, Pain.

[14]  P. Gross Circumventricular organs and body fluids , 1987 .

[15]  S. Gandevia,et al.  Perceptual distortions of the human body image produced by local anaesthesia, pain and cutaneous stimulation , 1999, The Journal of physiology.

[16]  J. Jacobs,et al.  Vascular leakage in the dorsal root ganglia of the rat, studied with horseradish peroxidase , 1976, Journal of the Neurological Sciences.

[17]  P. Bach-y-Rita Nonsynaptic Diffusion Neurotransmission and Late Brain Reorganization , 1995 .

[18]  P. Wall,et al.  Cross-excitation in dorsal root ganglia of nerve-injured and intact rats. , 1990, Journal of neurophysiology.

[19]  H. Gould,et al.  Rapid sodium channel augmentation in response to inflammation induced by complete Freund's adjuvant , 1998, Brain Research.

[20]  M. Devor,et al.  Chemically Mediated Cross-Excitation in Rat Dorsal Root Ganglia , 1996, The Journal of Neuroscience.

[21]  S. A. Scott Sensory Neurons: Diversity, Development, and Plasticity , 1992 .

[22]  S. Hyman REVIEW ■ : Regulation of Gene Expression by Neural Signals , 1996 .

[23]  M. Schachner,et al.  Expression of the Neural Recognition Molecule L1 by Cultured Neural Cells is influenced by K+ and the Glutamate Receptor Agonist NMDA , 1992, The European journal of neuroscience.

[24]  M. Devor,et al.  Trigeminal neuralgia: The role of self-sustaining discharge in the trigeminal ganglion , 1994, Pain.

[25]  R. Melzack,et al.  Experimental phantom limbs. , 1973, Experimental neurology.

[26]  C. Raine,et al.  Axon diameter and myelin thickness—unusual relationships in dorsal root ganglia , 1973, The Anatomical record.

[27]  J. Kiernan,et al.  Permeation of proteins from the blood into peripheral nerves and ganglia , 1994, Neuroscience.

[28]  R. G. Willison,et al.  Excitatory synaptic mechanisms , 1971 .

[29]  勝木 保次 Electrical activity of single cells , 1960 .

[30]  R. Baumgartner,et al.  Phantom and Stump Pain , 1981, Springer Berlin Heidelberg.

[31]  M. Devor,et al.  Structural basis of neuron-to-neuron cross-excitation in dorsal root ganglia , 1994, Journal of neurocytology.

[32]  P. Wall On the Origin of Pain Associated with Amputation , 1981 .

[33]  E. Rodriguez-Boulan,et al.  Polarity of epithelial and neuronal cells. , 1992, Annual review of cell biology.

[34]  E. Neher,et al.  Ca2+-Dependent Exocytosis in the Somata of Dorsal Root Ganglion Neurons , 1996, Neuron.

[35]  M. Devor,et al.  Functional cross-excitation between afferent A- and C-neurons in dorsal root ganglia , 1999, Neuroscience.

[36]  Fulton Bp Gap junctions in the developing nervous system. , 1995 .

[37]  R. Fields Signaling from Neural Impulses to Genes , 1996, The Neuroscientist : a review journal bringing neurobiology, neurology and psychiatry.

[38]  S. Rapoport,et al.  Transport properties of vertebrate blood-nerve barrier: Comparison with blood-brain barrier , 1994, Progress in Neurobiology.

[39]  M. Devor,et al.  Membrane differentiation in rat dorsal root ganglia and possible consequences for back pain , 1984, Neuroscience Letters.