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Galanin receptor 1 is expressed in a subpopulation of glutamatergic interneurons in the dorsal horn of the rat spinal cord
Author(s) -
Landry Marc,
BoualiBenazzouz Rabia,
André Caroline,
Shi Tie Jun Sten,
Léger Claire,
Nagy Frédéric,
Hökfelt Tomas
Publication year - 2006
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.21109
Subject(s) - glutamatergic , galanin , biology , spinal cord , neuroscience , glutamate receptor , inhibitory postsynaptic potential , in situ hybridization , neuropeptide , receptor , glutamate decarboxylase , microbiology and biotechnology , gene expression , biochemistry , gene , enzyme
The 29/30 amino acid neuropeptide galanin has been implicated in pain processing at the spinal level and local dorsal horn neurons expressing the Gal 1 receptor may play a critical role. In order to determine the transmitter identity of these neurons, we used immunohistochemistry and antibodies against the Gal 1 receptor and the three vesicular glutamate transporters (VGLUTs), as well as in situ hybridization, to explore a possible glutamatergic phenotype. Gal 1 protein, which could not be demonstrated in Gal 1 knockout mice, colocalized with VGLUT2 protein, but not with glutamate decarboxylase, in many nerve endings in lamina II. Moreover, Gal 1 and VGLUT2 transcripts were often found in the same cell bodies in laminae I–IV. Gal 1 ‐protein and galanin‐peptide showed an overlapping distribution but were not colocalized. Gal 1 staining did not appear to be affected by dorsal rhizotomy. Taken together, these findings provide strong evidence that Gal 1 is a heteroreceptor expressed on excitatory glutamatergic dorsal horn interneurons. Activation of such Gal 1 receptors may thus decrease the inhibitory tone in the superficial dorsal horn, and possibly cause antinociception. J. Comp. Neurol. 499:391–403, 2006. © 2006 Wiley‐Liss, Inc.