Galanin-immunoreactivity identifies a distinct population of inhibitory interneurons in laminae I-III of the rat spinal cord

Tiong, S. Y.X., Polgár, E., van Kralingen, J. C., Watanabe, M. and Todd, A. J. (2011) Galanin-immunoreactivity identifies a distinct population of inhibitory interneurons in laminae I-III of the rat spinal cord. Molecular Pain, 7, 36. (doi: 10.1186/1744-8069-7-36) (PMID:21569622) (PMCID:PMC3118366)

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Abstract

Background: Inhibitory interneurons constitute 30-40% of neurons in laminae I-III and have an important anti-nociceptive role. However, because of the difficulty in classifying them we know little about their organisation. Previous studies have identified 3 non-overlapping groups of inhibitory interneuron, which contain neuropeptide Y (NPY), neuronal nitric oxide synthase (nNOS) or parvalbumin, and have shown that these differ in postsynaptic targets. Some inhibitory interneurons contain galanin and the first aim of this study was to determine whether these form a different population from those containing NPY, nNOS or parvalbumin. We also estimated the proportion of neurons and GABAergic axons that contain galanin in laminae I-III. Results: Galanin cells were concentrated in laminae I-IIo, with few in laminae IIi-III. Galanin showed minimal co-localisation with NPY, nNOS or parvalbumin in laminae I-II, but most galanin-containing cells in lamina III were nNOS-positive. Galanin cells constituted similar to 7%, 3% and 2% of all neurons in laminae I, II and III, and we estimate that this corresponds to 26%, 10% and 5% of the GABAergic neurons in these laminae. However, galanin was only found in similar to 6% of GABAergic boutons in laminae I-IIo, and similar to 1% of those in laminae IIi-III. Conclusions: These results show that galanin, NPY, nNOS and parvalbumin can be used to define four distinct neurochemical populations of inhibitory interneurons. Together with results of a recent study, they suggest that the galanin and NPY populations account for around half of the inhibitory interneurons in lamina I and a quarter of those in lamina II

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Van Kralingen, Ms Josie and Beresford-Polgar, Dr Erika and Todd, Professor Andrew
Authors: Tiong, S. Y.X., Polgár, E., van Kralingen, J. C., Watanabe, M., and Todd, A. J.
College/School:College of Medical Veterinary and Life Sciences > School of Psychology & Neuroscience
Journal Name:Molecular Pain
Publisher:BioMed Central
ISSN:1744-8069
ISSN (Online):1744-8069
Copyright Holders:Copyright © 2011 Tiong et al
First Published:First published in Molecular Pain 7: 36
Publisher Policy:Reproduced under a Creative Commons License

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