Inhibitory interneurons that express GFP in the PrP-GFP mouse spinal cord are morphologically heterogeneous, innervated by several classes of primary afferent and include lamina I projection neurons among their postsynaptic targets

Ganley, R. P. et al. (2015) Inhibitory interneurons that express GFP in the PrP-GFP mouse spinal cord are morphologically heterogeneous, innervated by several classes of primary afferent and include lamina I projection neurons among their postsynaptic targets. Journal of Neuroscience, 35(19), pp. 7626-7642. (doi:10.1523/JNEUROSCI.0406-15.2015) (PMID:25972186) (PMCID:PMC4429159)

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Abstract

The superficial dorsal horn of the spinal cord contains numerous inhibitory interneurons, which regulate the transmission of information perceived as touch, pain or itch. Despite the importance of these cells, our understanding of their roles in the neuronal circuitry is limited by the difficulty in identifying functional populations. One group that has been identified and characterised consists of cells in the mouse that express green fluorescent protein (GFP) under control of the prion protein (PrP) promoter. Previous reports suggested that PrP-GFP cells belonged to a single morphological class (central cells), received inputs exclusively from unmyelinated primary afferents and had axons that remained in lamina II. However, we recently reported that the PrP-GFP cells expressed neuronal nitric oxide synthase (nNOS) and/or galanin, and it has been shown that nNOS-expressing cells are more diverse in their morphology and synaptic connections. We therefore used a combined electrophysiological, pharmacological and anatomical approach to re-examine the PrP-GFP cells. We provide evidence that they are morphologically diverse (corresponding to "unclassified" cells) and receive synaptic input from a variety of primary afferents, with convergence onto individual cells. We also show that their axons project into adjacent laminae, and that they target putative projection neurons in lamina I. This indicates that the neuronal circuitry involving PrP-GFP cells is more complex than previously recognised, and suggests that they are likely to have several distinct roles in regulating the flow of somatosensory information through the dorsal horn.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Boyle, Dr Kieran and Iwagaki, Mr Noboru and Beresford-Polgar, Dr Erika and Todd, Professor Andrew and Del Rio, Dr Patricia and Dickie, Dr Allen and Riddell, Dr John
Authors: Ganley, R. P., Iwagaki, N., Del Rio, P., Baseer, N., Dickie, A. C., Boyle, K. A., Polgár, E., Watanabe, M., Abraira, V. E., Zimmerman, A., Riddell, J. S., and Todd, A. J.
College/School:College of Medical Veterinary and Life Sciences > Institute of Neuroscience and Psychology
Journal Name:Journal of Neuroscience
Publisher:The Society for Neuroscience
ISSN:0270-6474
ISSN (Online):1529-2401
Copyright Holders:Copyright © 2015 The Authors
First Published:First published in Journal of Neuroscience 35(19):7626-7642
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
571071Modulating cutaneous afferent input: Identifying a source of presynaptic (axo-axonic) inputs in the mouse spinal dorsal hornDavid I HughesBiotechnology and Biological Sciences Research Council (BBSRC)BB/J000620/1RI NEUROSCIENCE & PSYCHOLOGY
627371Spinal inhibitory interneurons that suppress itchAndrew ToddMedical Research Council (MRC)MR/L003430/1INP - CENTRE FOR NEUROSCIENCE