Bicuculline and strychnine suppress the mesencephalic locomotor region-induced inhibition of group III muscle afferent input to the dorsal horn

A. M. Degtyarenko, Marc P Kaufman

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

We examined the effect of iontophoretic application of bicuculline methiodide and strychnine hydrochloride on the mesencephalic locomotor region (MLR)-induced inhibition of dorsal horn cells in paralyzed cats. The activity of 60 dorsal horn cells was recorded extracellularly in laminae I, II, V-VII of spinal segments L7-S1. Each of the cells was shown to receive group III muscle afferent input as demonstrated by their responses to electrical stimulation of the tibial nerve (mean latency and threshold of activation: 20.1±6.4 ms and 15.2±1.4 times motor threshold, respectively). Electrical stimulation of the MLR suppressed transmission in group III muscle afferent pathways to dorsal horn cells. Specifically the average number of impulses generated by the dorsal horn neurons in response to a single pulse applied to the tibial nerve was decreased by 78±2.8% (n=60) during the MLR stimulation. Iontophoretic application (10-50 nA) of bicuculline and strychnine (5-10 mM) suppressed the MLR-induced inhibition of transmission of group III afferent input to laminae I and II cells by 69±5% (n=10) and 29±7% (n=7), respectively. Likewise, bicuculline and strychnine suppressed the MLR-induced inhibition of transmission of group III afferent input to lamina V cells by 59±13% (n=14) and 39±11% (n=10), respectively. Our findings raise the possibility that GABA and glycine release onto dorsal horn neurons in the spinal cord may play an important role in the suppression by central motor command of thin fiber muscle afferent-reflex pathways.

Original languageEnglish (US)
Pages (from-to)779-788
Number of pages10
JournalNeuroscience
Volume118
Issue number3
DOIs
StatePublished - May 25 2003

Fingerprint

Posterior Horn Cells
Strychnine
Bicuculline
Muscles
Afferent Pathways
Tibial Nerve
Electric Stimulation
Substantia Gelatinosa
Glycine
gamma-Aminobutyric Acid
Reflex
Spinal Cord
Cats
Spinal Cord Dorsal Horn
Inhibition (Psychology)

Keywords

  • Central command
  • Descending inhibition
  • Exercise pressor reflex
  • Locomotion
  • Tibial nerve

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Bicuculline and strychnine suppress the mesencephalic locomotor region-induced inhibition of group III muscle afferent input to the dorsal horn. / Degtyarenko, A. M.; Kaufman, Marc P.

In: Neuroscience, Vol. 118, No. 3, 25.05.2003, p. 779-788.

Research output: Contribution to journalArticle

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abstract = "We examined the effect of iontophoretic application of bicuculline methiodide and strychnine hydrochloride on the mesencephalic locomotor region (MLR)-induced inhibition of dorsal horn cells in paralyzed cats. The activity of 60 dorsal horn cells was recorded extracellularly in laminae I, II, V-VII of spinal segments L7-S1. Each of the cells was shown to receive group III muscle afferent input as demonstrated by their responses to electrical stimulation of the tibial nerve (mean latency and threshold of activation: 20.1±6.4 ms and 15.2±1.4 times motor threshold, respectively). Electrical stimulation of the MLR suppressed transmission in group III muscle afferent pathways to dorsal horn cells. Specifically the average number of impulses generated by the dorsal horn neurons in response to a single pulse applied to the tibial nerve was decreased by 78±2.8{\%} (n=60) during the MLR stimulation. Iontophoretic application (10-50 nA) of bicuculline and strychnine (5-10 mM) suppressed the MLR-induced inhibition of transmission of group III afferent input to laminae I and II cells by 69±5{\%} (n=10) and 29±7{\%} (n=7), respectively. Likewise, bicuculline and strychnine suppressed the MLR-induced inhibition of transmission of group III afferent input to lamina V cells by 59±13{\%} (n=14) and 39±11{\%} (n=10), respectively. Our findings raise the possibility that GABA and glycine release onto dorsal horn neurons in the spinal cord may play an important role in the suppression by central motor command of thin fiber muscle afferent-reflex pathways.",
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