A quantitative study of neurochemically-defined populations of inhibitory interneurons in the superficial dorsal horn of the mouse spinal cord

Boyle, K. A., Gutierrez-Mecinas, M. , Polgár, E., Mooney, N., O'Connor, E., Furuta, T., Watanabe, M. and Todd, A. J. (2017) A quantitative study of neurochemically-defined populations of inhibitory interneurons in the superficial dorsal horn of the mouse spinal cord. Neuroscience, 363, pp. 120-133. (doi: 10.1016/j.neuroscience.2017.08.044) (PMID:28860091) (PMCID:PMC5648048)

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Abstract

Around a quarter of neurons in laminae I-II of the dorsal horn are inhibitory interneurons. These play an important role in modulating somatosensory information, including that perceived as pain or itch. Previous studies in rat identified four largely non-overlapping neurochemical populations among these cells, defined by expression of galanin, neuropeptide Y (NPY), neuronal nitric oxide synthase (nNOS) or parvalbumin. The galanin cells were subsequently shown to coexpress dynorphin. Several recent studies have used genetically-modified mice to investigate the function of different interneuron populations, and it is therefore important to determine whether the same pattern applies in mouse, and to estimate the relative sizes of these populations. We show that the neurochemical organisation of inhibitory interneurons in mouse superficial dorsal horn is similar to that in the rat, although a larger proportion of these neurons (33%) express NPY. Between them, these four populations account for ∼75% of inhibitory cells in laminae I-II. Since ∼25% of inhibitory interneurons in this region belong to a novel calretinin-expressing type, our results suggest that virtually all inhibitory interneurons in superficial dorsal horn can be assigned to one of these five neurochemical populations. Although our main focus was inhibitory neurons, we also identified a population of excitatory dynorphin-expressing cells in laminae I-II that are largely restricted to the medial part of the mid-lumbar dorsal horn, corresponding to glabrous skin territory. These findings are important for interpretation of studies using molecular-genetic techniques to manipulate the functions of interneuron populations to investigate their roles in somatosensory processing.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Boyle, Dr Kieran and Gutierrez-Mecinas, Dr Maria and Beresford-Polgar, Dr Erika and Todd, Professor Andrew
Authors: Boyle, K. A., Gutierrez-Mecinas, M., Polgár, E., Mooney, N., O'Connor, E., Furuta, T., Watanabe, M., and Todd, A. J.
College/School:College of Medical Veterinary and Life Sciences > Institute of Neuroscience and Psychology
Journal Name:Neuroscience
Publisher:Elsevier
ISSN:0306-4522
ISSN (Online):1873-7544
Published Online:30 August 2017
Copyright Holders:Copyright © 2017 Elsevier
First Published:First published in Neuroscience 363:120-133
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
644164Defining pain circuitry in health and diseaseAndrew ToddWellcome Trust (WELLCOTR)102645/Z/13/ZINP - CENTRE FOR NEUROSCIENCE
689031The role of NPY-containing inhibitory interneurons in spinal pain pathwaysAndrew ToddBiotechnology and Biological Sciences Research Council (BBSRC)BB/N006119/1INP - CENTRE FOR NEUROSCIENCE
627371Spinal inhibitory interneurons that suppress itchAndrew ToddMedical Research Council (MRC)MR/L003430/1INP - CENTRE FOR NEUROSCIENCE