Metabotropic synaptic regulation of intrinsic response properties of turtle spinal motoneurones

Authors

  • Rodolfo Delgado-Lezama,

    1. Department of Medical Physiology, Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
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  • Jean-Francois Perrier,

    1. Department of Medical Physiology, Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
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  • Steen Nedergaard,

    1. Department of Medical Physiology, Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
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  • Gytis Svirskis,

    1. Department of Medical Physiology, Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
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  • Jørn Hounsgaard

    Corresponding author
    1. Department of Medical Physiology, Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
    • To whom correspondence should be addressed. This manuscript was accepted as a Short Paper for rapid publication.

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  • Authors' present addresses
    S. Nedergaard: Institute of Physiology, Aarhus University, DK-8000 Aarhus C, Denmark.

  • Authors' present addresses
    G. Svirskis: Laboratory of Neurophysiology, Biomedical Research Institute, Kaunas Medical Academy, 3000 Kaunas, Lithuania.

  • Author's email address
    J. Hounsgaard: j.hounsgaard@mfi.ku.dk

Abstract

  • 1The effect of a brief train of electric stimuli in the dorsolateral funiculus on the intrinsic response properties of turtle motoneurones was investigated in transverse sections of the spinal cord in vitro.
  • 2Even when glutamatergic, GABAergic and glycinergic ionotropic synaptic transmission was blocked by antagonists of AMPA, NMDA, glycine and GABA receptors, dorsolateral funiculus (DLF) stimulation induced a facilitation of plateau potentials during current clamp and the underlying inward current in voltage clamp. This facilitation lasted more than 10 s.
  • 3The plateau potential and the facilitation by DLF stimulation was absent in the presence of 10 μm nifedipine. The DLF-induced facilitation was reduced by antagonists of 5-HT1a, group 1 metabotropic glutamate receptors and muscarine receptors.
  • 4These findings suggest that the intrinsic properties of spinal motoneurones are dynamically regulated by afferent synaptic activity. These afferents can be of spinal and extraspinal origin. Continuous regulation of intrinsic response properties could be a mechanism for motor flexibility.

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