title: Electrophysiological responses from vagus nerve stimulation in rats.
abstract: The mechanism of action of vagus nerve stimulation (VNS) for pharmacoresistant epilepsy is unknown and the therapeutic outcome is highly variable. We investigated stimulation-induced vagus nerve electrophysiological responses in rats using various stimulation parameters. Conduction velocity, I(50), rheobase and chronaxie were calculated. We identified an early and late component corresponding to an afferent compound action potential (CAP) and a remote laryngeal motor-evoked potential (LMEP), respectively. The conduction velocity (CAP: 26.2 ± 1.4 m/s; LMEP: 32.4 ± 2.4 m/s) and I(50) (CAP: 2.4 ± 0.3 mA; LMEP: 1.8±0.2 mA) were significantly different for both components, the rheobase (CAP: 140±30 μA; LMEP: 110±26 μA) and chronaxie (CAP: 66±7 μs; LMEP: 73±9 μs) were not. Using a pulse of 10 μs, the CAP saturated between 4-5 mA. Our method can be used to record VNS-induced electrophysiological responses in rats and provides an objective biomarker for electrical stimulation with various parameters in an experimental set-up. Our findings are potentially useful for clinical purposes in the sense that combination of VNS and recording of vagal nerve CAPs may help clinicians to determine the individual optimal intensity required to fully activate fast-conducting afferent fibers.
authors.affiliation: Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology, Department of Neurology, Institute for Neuroscience, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium.
authors.forename: Lies
authors.initials: L
authors.lastname: Mollet
authors.forename: Robrecht
authors.initials: R
authors.lastname: Raedt
authors.forename: Jean
authors.initials: J
authors.lastname: Delbeke
authors.forename: Riëm
authors.initials: R
authors.lastname: El Tahry
authors.forename: Annelies
authors.initials: A
authors.lastname: Grimonprez
authors.forename: Ine
authors.initials: I
authors.lastname: Dauwe
authors.forename: Veerle
authors.initials: V
authors.lastname: DE Herdt
authors.forename: Alfred
authors.initials: A
authors.lastname: Meurs
authors.forename: Wytse
authors.initials: W
authors.lastname: Wadman
authors.forename: Paul
authors.initials: P
authors.lastname: Boon
authors.forename: Kristl
authors.initials: K
authors.lastname: Vonck
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D014630:Vagus Nerve / Q000502:physiology*; D055536:Vagus Nerve Stimulation