title: Calcium dependence of axotomized sensory neurons excitability.
abstract: Hyperexcitability of axotomized dorsal root ganglion neurons is thought to play a role in neuropathic pain. Numerous changes in ionic channels expression or current amplitude are reported after an axotomy, but to date no direct correlation between excitability of axotomized sensory neurons and ionic channels alteration has been provided. Following sciatic nerve injury, we examined, under whole-cell patch clamp recording, the effects of calcium homeostasis on the electrical activity of axotomized medium-sized sensory neurons isolated from lumbar dorsal root ganglia of adult mice. Axotomy induced an increase in excitability of medium sensory neurons among which 25% develop a propensity to fire repetitively. The condition necessary to get burst discharge in axotomized neurons was the presence of a high intracellular Ca2+ buffer concentration. The main effect was to amplify the increase in threshold current and apparent input resistance induced by axotomy. These data supply evidence for a role of Ca2+-dependent mechanisms in the control of excitability of axotomized sensory neurons.
authors.affiliation: INSERM U 583, Hopital St. Eloi, 80, rue Augustin Fliche, BP 74103, 34091 Montpellier Cedex 5, France.
authors.forename: Cécile
authors.initials: C
authors.lastname: Hilaire
authors.forename: Perrine
authors.initials: P
authors.lastname: Inquimbert
authors.forename: Mohammed
authors.initials: M
authors.lastname: Al-Jumaily
authors.forename: Denis
authors.initials: D
authors.lastname: Greuet
authors.forename: Jean
authors.initials: J
authors.lastname: Valmier
authors.forename: Frédérique
authors.initials: F
authors.lastname: Scamps
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D019771:Axotomy; D002021:Buffers; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000502:physiology*; D048429:Cell Size; D004195:Disease Models, Animal; D017097:Electric Impedance; D005260:Female; D005727:Ganglia, Spinal / Q000378:metabolism* / Q000503:physiopathology; D006706:Homeostasis / Q000502:physiology; D007424:Intracellular Fluid / Q000378:metabolism; D051379:Mice; D009437:Neuralgia / Q000378:metabolism* / Q000503:physiopathology; D009475:Neurons, Afferent / Q000378:metabolism* / Q000473:pathology; D018408:Patch-Clamp Techniques; D010523:Peripheral Nervous System Diseases / Q000378:metabolism* / Q000503:physiopathology; D012584:Sciatic Nerve / Q000378:metabolism / Q000503:physiopathology; D020426:Sciatic Neuropathy / Q000378:metabolism* / Q000503:physiopathology
chemical_list: D002021:Buffers; D002118:Calcium