Expression of Vesicular Glutamate Transporters in Rat Lumbar Spinal Cord, with a Note on Dorsal Root Ganglia
J. Comp. Neurol.. 2003-01-01; 468(3): 380-394
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1. J Comp Neurol. 2004 Jan 12;468(3):380-94.
Expression of vesicular glutamate transporters in rat lumbar spinal cord, with a
note on dorsal root ganglia.
Landry M(1), Bouali-Benazzouz R, El Mestikawy S, Ravassard P, Nagy F.
(1)Institut National de la Santé et de la Recherche Médicale, E 358, Université
Bordeaux 2, Institut François Magendie, 33 077 Bordeaux, France.
Three vesicular glutamate transporters (VGLUTs) have been recently identified and
their distribution has been mapped in various brain areas. In the present study,
we used morphological approaches to investigate their expression in the rat
lumbar spinal cord and dorsal root ganglia. Our results show a complementary
distribution of VGLUT-expressing fibers in the spinal cord, with no overlapping
in nerve endings. In the dorsal horn, VGLUT1 is most abundant in
mechanosensory/proprioceptive deep afferent fibers. VGLUT2 and VGLUT3 are
expressed only at moderate levels in primary sensory afferent fibers and are not
used by central projections of nociceptive neurons. VGLUT1 and VGLUT2 mRNAs are
mainly segregated in superficial laminae but colocalized in deeper laminae. Weak
expression of VGLUT3 mRNA is only detected in deep laminae. The colocalization of
VGLUT1 and VGLUT2 transcripts in most sensory neurons of the dorsal root ganglia
is not in agreement with the clear segregation between the proteins in their
spinal projections. Such a discrepancy suggests targeting mechanisms specific for
each transporter and/or a distinct regulation of their translation. In the
ventral horn, the expression of VGLUT1 and VGLUT2 mRNAs in motoneuron perikarya
suggests the possible unexpected role of glutamate in the vertebrate
neuromuscular junction. These results demonstrate the existence of different
subpopulations of glutamate nerve terminals in the rat lumbar spinal cord and
suggest that functionally distinct subsets of excitatory glutamatergic neuronal
networks are involved in sensory processing and motor control.
Copyright 2003 Wiley-Liss, Inc.
PMID: 14681932 [Indexed for MEDLINE]