Subpopulations of GABAergic and non-GABAergic rat dorsal horn neurons express Ca2+-permeable AMPA receptors

C. Aluquerque, Changjoon Lee, A. C. Jackson, A. B. MacDermott

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Abstract

Subpopulations of α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptors that are either permeable or impermeable to Ca2+ are expressed on dorsal horn neurons in culture. While both mediate synaptic transmission, the Ca2+-permeable AMPA receptors provide a Ca2+ signal that may resut in a transient change in synaptic strength. To appreciate the relevance of these receptors to dorsal horn physiology, we have investigated whether they show selective expression n identified subpopulations of dorsal horn neurons. Expression of Ca2+-permeable AMPA receptors was assayed using the kainate-induced cobalt loading technique first developed by Pruss et al. Subpopulations of dorsal horn neurons were identified using immunocytochemistry for γ-aminobutyric acid (GABA), glycine, substance P receptor (NK1 receptor) and the Ca2+-binding proteins, calretinin and calbindin D28K. We demonstrate that, in dorsal horn neurons in culture, kainate-induced cobalt uptake is selectively mediated by Ca2+-permeable AMPA receptors, and that a majority of GABA and NK1 receptor-expressing neurons express Ca2+-permeable AMPA receptors. GABAergic dorsal horn neurons are important in local inhibition as well as in the regulation of transmitter release from primary afferent terminals. NK1 receptor-expressing dorsal horn neurons include many of the projection neurons in the nociceptive spino-thalamic pathway. Thus, we have identified two populations of dorsal horn neurons representing important components of dorsal horn function that express Ca2+-permeable AMPA receptors. Furthermore, we show that several subpopulations of putative excitatory interneurons defined by calretinin and calbindin expression do not express Ca2+-permeable AMPA receptors.

Original languageEnglish
Pages (from-to)2758-2766
Number of pages9
JournalEuropean Journal of Neuroscience
Volume11
Issue number8
DOIs
Publication statusPublished - 1999 Aug 12
Externally publishedYes

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Keywords

  • Calbindin
  • Calretinin
  • Cobalt
  • NK1 receptor
  • Spinal cord

ASJC Scopus subject areas

  • Neuroscience(all)

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