Baclofen and the Release of Neuropeptides in the Cat Spinal Cord

Authors

  • C. R. Morton,

    Corresponding author
    1. Division of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, A.C.T. 2601, Australia
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  • W. D. Hutchison,

    1. Division of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, A.C.T. 2601, Australia
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    • 1

      Department of Physiology, University of Toronto, Toronto, Ontario, Canada

  • G. Lacey

    1. Division of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, A.C.T. 2601, Australia
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C. R. Morton, as above

Abstract

The antibody microprobe technique was used to study the effect of baclofen on the release of immunoreactive substance P and immunoreactive calcitonin gene-related peptide within the lower lumbar spinal cord of pentobarbitone-anaesthetized spinalized cats. Both peptides were released in the region of the substantia gelatinosa during ipsilateral noxious cutaneous stimulation or high-intensity electrical stimulation of a hind limb nerve. Intravenous administration of baclofen suppressed the excitation of lumbar dorsal horn neurons, but did not produce detectable alterations of the evoked release of immunoreactive substance P or immunoreactive calcitonin gene-related peptide in the superficial grey matter dorsal to these neurons. The results suggest that the antinociceptive action of baclofen does not involve a reduction of the intraspinal release of substance P or calcitonin gene-related peptide from the central terminals of nociceptive sensory fibres.

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