Presynaptic NMDA receptors modulate glutamate release from primary sensory neurons in rat spinal cord dorsal horn.
NMDA receptors have the potential to produce complex activity-dependent regulation of transmitter release when localized presynaptically. In the somatosensory system, NMDA receptors have been immunocytochemically detected on presynaptic terminals of primary afferents, and these have been proposed to drive release of substance P from central terminals of a subset of nociceptors in the spinal cord dorsal horn. Here we report that functional NMDA receptors are indeed present at or near the central terminals of primary afferent fibers. Furthermore, we show that activation of these presynaptic receptors results in an inhibition of glutamate release from the terminals. Some of these NMDA receptors may be expressed in the preterminal axon and regulate the extent to which action potentials invade the extensive central arborizations of primary sensory neurons.
Bardoni
Rita
R
Department of Biomedical Sciences, University of Modena and Reggio Emilia, 41100 Modena, Italy. bardoni@unimo.it
Torsney
Carole
C
Tong
Chi-Kun
CK
Prandini
Massimiliano
M
MacDermott
Amy B
AB
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D018698:Glutamic Acid / Q000378:metabolism*; D066298:In Vitro Techniques; D016202:N-Methylaspartate / Q000494:pharmacology; D009475:Neurons, Afferent / Q000187:drug effects / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D020671:Posterior Horn Cells / Q000187:drug effects / Q000378:metabolism*; D017729:Presynaptic Terminals / Q000378:metabolism*; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*
D018690:Excitatory Amino Acid Agonists; D016194:Receptors, N-Methyl-D-Aspartate; D018698:Glutamic Acid; D016202:N-Methylaspartate