Localization of a metabotropic glutamate receptor, mGluR7, in axon terminals of presumed nociceptive, primary afferent fibers in the superficial layers of the spinal dorsal horn: an electron microscope study in the rat

1997 ◽  
Vol 223 (3) ◽  
pp. 153-156 ◽  
Author(s):  
He Li ◽  
Hitoshi Ohishi ◽  
Ayae Kinoshita ◽  
Ryuichi Shigemoto ◽  
Sakashi Nomura ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Glutamate Receptor ◽  
Electron Microscope Study ◽  
Spinal Dorsal Horn ◽  
Metabotropic Glutamate Receptor ◽  
Metabotropic Glutamate ◽  
Axon Terminals ◽  
Spinal Dorsal ◽  
Afferent Fibers ◽  
Primary Afferent Fibers

The metabotropic glutamate receptor subtype mGluR 2/3 is located at extrasynaptic loci in rat spinal dorsal horn synapses

2000 ◽  
Vol 287 (3) ◽  
pp. 236-238 ◽  
Author(s):  
Jon Jatsu Azkue ◽  
José Marı́a Mateos ◽  
Izaskun Elezgarai ◽  
Rocı́o Benı́tez ◽  
Alexandra Osorio ◽  
...  
Keyword(s):  
Dorsal Horn ◽  
Glutamate Receptor ◽  
Spinal Dorsal Horn ◽  
Metabotropic Glutamate Receptor ◽  
Receptor Subtype ◽  
Metabotropic Glutamate ◽  
Spinal Dorsal

Synergistic Enhancement of Glutamate-Mediated Responses by Serotonin and Forskolin in Adult Mouse Spinal Dorsal Horn Neurons

2002 ◽  
Vol 87 (2) ◽  
pp. 732-739 ◽  
Author(s):  
Guo-Du Wang ◽  
Min Zhuo
Keyword(s):  
Spinal Cord ◽  
Nmda Receptors ◽  
Dorsal Horn ◽  
Spinal Dorsal Horn ◽  
Adult Mouse ◽  
Dorsal Horn Neurons ◽  
Spinal Dorsal ◽  
Afferent Fibers ◽  
Primary Afferent Fibers ◽  
Spinal Dorsal Horn Neurons

Glutamate is the major excitatory amino acid neurotransmitter in the CNS, including the neocortex, hippocampus, and spinal cord. Normal synaptic transmission is mainly mediated by glutamate AMPA and/or kainate receptors. Glutamate N-methyl-d-aspartate (NMDA) receptors are normally inactive and only activated when a sufficient postsynaptic depolarization is induced by the activity. Here we show that in sensory synapses of adult mouse, some synaptic responses (26.3% of a total of 38 experiments) between primary afferent fibers and dorsal horn neurons are almost completely mediated by NMDA receptors. Dorsal root stimulation did not elicit any detectable AMPA/kainate receptor-mediated responses in these synapses. Unlike young spinal cord, serotonin alone did not produce any long-lasting synaptic enhancement in adult spinal dorsal horn neurons. However, co-application of the adenylyl cyclase activator forskolin and serotonin (5-HT) produced long-lasting enhancement, including the recruitment of functional AMPA receptor-mediated responses. Calcium-sensitive, calmodulin-regulated adenylyl cyclases (AC1, AC8) are required for the enhancement. Furthermore the thresholds for generating action potential responses were decreased, and, in many cases, co-application of forskolin and 5-HT led to the generation of action potentials by previously subthreshold stimulation of primary afferent fibers in the presence of the NMDA receptor blocker 2-amino-5-phosphonovaleric acid. Our results suggest that pure NMDA synapses exist on sensory neurons in adult spinal cord and that they may contribute to functional sensory transmission. The synergistic recruitment of functional AMPA responses by 5-HT and forskolin provides a new cellular mechanism for glutamatergic synapses in mammalian spinal cord.

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