Membrane excitability changes in hindlimb motoneurons induced by stimulation of the locus coeruleus in cats |
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| Authors: | S J Fung C D Barnes |
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| Affiliation: | 1. Sustainability Assessment Program (SAP), School of Civil and Environmental Engineering, UNSW Sydney, NSW 2052, Australia;2. ISA, School of Physics A28, The University of Sydney, Australia, NSW 2006, Australia;3. School of Life and Environmental Sciences, Centre for Integrative Ecology, Deakin University, Melbourne, Burwood, VIC 3125, Australia;1. Department of Materials Science and Engineering & Research Institute of Advanced Materials, Seoul National University, Seoul, 08826, Republic of Korea;2. Advanced Materials Development Team, Korea Atomic Energy Research Institute, Daejeon, 34057, Republic of Korea;3. College of Materials Science and Engineering, Beijing University of Technology, Beijing, 100124, China;1. Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA;2. Department of Ecology and Natural Resources, Universidade Federal do Ceará, Fortaleza, CE 60440-900, Brazil;1. State Key Laboratory for Mineral Deposit Research, School of Earth Sciences and Engineering, Nanjing University, China;2. Université d’Orléans, CNRS/INSU – ISTO – BRGM, UMR 7327, Orléans, France;1. Department of Neurology, 4BRAIN Research Group, Ghent University Hospital, Ghent, Belgium;2. Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands;3. Swammerdam Institute of Life Sciences, University of Amsterdam, Amsterdam, The Netherlands |
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| Abstract: | ![]()
The present analysis describes the cellular mechanisms underlying the heightened membrane excitability of hindlimb flexor and extensor motoneurons upon stimulation of the locus coeruleus (LC) in unanesthetized, decerebrate cats. In a total of 73 cells, brief train stimuli to the LC at 50-300 microA intensity evoked one of 4 patterns of motoneuronal responses: a simple excitatory postsynaptic potential (EPSP) with weak trailing depolarization, a double-peak EPSP, an EPSP succeeded by a weak hyperpolarization, or a slow rising EPSP. As the initial dominant EPSP was a consistent finding among all cells and the ensuing potentials were variable in polarity, quantitative characterization was focused on the initial EPSP only. In all cells tested (n = 11), the LC-EPSP was accompanied by a decrease in input resistance. The excitatory LC action was further demonstrated by the consistent (n = 25 cells) motoneuron rheobase decrease when the latter was measured coincident with the summit of an LC-EPSP. Furthermore, the time course of the single-spike afterhyperpolarization became shortened during the LC conditioning stimuli (n = 16 motoneurons). Our data show that the descending LC action on motoneurons is typified by an EPSP accompanied by a net decrease in input resistance as well as a concurrent increase in motoneuron electrical excitability. |
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