Glutamate transmission in the rostral ventrolateral medullary sympathetic premotor pathway

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Abstract

1. The aim of these studies was to test the hypothesis that glutamate is the principal excitatory neurotransmitter in the sympathetic premotor pathway from the rostral ventrolateral medulla (RVLM) to the sympathetic preganglionic neurons (SPNs) in the thoracic spinal cord. 2. Iontophoretic and pressure ejection of glutamate receptor agonists and antagonists was made onto antidromically identified splanchnic and adrenal SPNs before and during electrical stimulation of the RVLM in urethane/chloralose-anesthetized, artificially ventilated rats. 3. SPNs were excited by both NMDA and non-NMDA glutamate receptor agonists. Blockade of glutamate receptors in the IML interrupted the ability of electrical activation of sympathetic premotor neurons in the RVLM to excite SPNs. Within the IML, antergradely labeled terminals of RVLM neurons were found to contain glutamate immunoreactivity and to make asymmetric synapses on local dendrites. 4. These data support a significant role for glutamate neurotransmission in mediating the tonic and phasic excitation of SPNs by the sympathetic premotor pathway from the RVLM. It seems likely that stimulation of the RVLM produces glutamate release from both C1 and non-PNMT-containing axon terminals in the IML.

Original languageEnglish (US)
Pages (from-to)761-772
Number of pages12
JournalCellular and Molecular Neurobiology
Volume23
Issue number4-5
DOIs
StatePublished - Oct 1 2003

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Keywords

  • Excitatory amino acid
  • Glutamate
  • Immunocytochemistry
  • Iontophoresis
  • PNMT
  • Preganglionic neuron
  • RVLM
  • Sympathetic nervous system

ASJC Scopus subject areas

  • Cellular and Molecular Neuroscience
  • Cell Biology

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