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

Eur J Neurosci. 1999 Aug;11(8):2758-66. doi: 10.1046/j.1460-9568.1999.00691.x.


Subpopulations of alpha-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 result in a transient change in synaptic strength [Gu, J.G., Albuquerque, C., Lee, C.J. & MacDermott, A.B. (1996) Nature, 381, 793]. To appreciate the relevance of these receptors to dorsal horn physiology, we have investigated whether they show selective expression in 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. [Pruss, R.M., Akeson, R.L., Racke, M.M. & Wilburn, J.L. (1991) Neuron, 7, 509]. Subpopulations of dorsal horn neurons were identified using immunocytochemistry for gamma-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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aging / metabolism
  • Animals
  • Calcium / metabolism*
  • Calcium-Binding Proteins / metabolism
  • Cobalt / pharmacokinetics
  • Glycine / metabolism
  • Immunohistochemistry
  • N-Methylaspartate / pharmacology
  • Neurons / metabolism*
  • Neurotoxins / pharmacology
  • Permeability
  • Rats
  • Receptors, AMPA / metabolism*
  • Receptors, Neurokinin-1 / metabolism
  • Spinal Cord / cytology
  • Spinal Cord / drug effects
  • Spinal Cord / metabolism*
  • Tyrosine 3-Monooxygenase / metabolism
  • gamma-Aminobutyric Acid / metabolism*


  • Calcium-Binding Proteins
  • Neurotoxins
  • Receptors, AMPA
  • Receptors, Neurokinin-1
  • Cobalt
  • gamma-Aminobutyric Acid
  • N-Methylaspartate
  • Tyrosine 3-Monooxygenase
  • Calcium
  • Glycine