TY - JOUR T1 - Inhibitory Interneurons That Express GFP in the <em>PrP-GFP</em> Mouse Spinal Cord Are Morphologically Heterogeneous, Innervated by Several Classes of Primary Afferent and Include Lamina I Projection Neurons among Their Postsynaptic Targets JF - The Journal of Neuroscience JO - J. Neurosci. SP - 7626 LP - 7642 DO - 10.1523/JNEUROSCI.0406-15.2015 VL - 35 IS - 19 AU - Robert P. Ganley AU - Noboru Iwagaki AU - Patricia del Rio AU - Najma Baseer AU - Allen C. Dickie AU - Kieran A. Boyle AU - Erika Polgár AU - Masahiko Watanabe AU - Victoria E Abraira AU - Amanda Zimmerman AU - John S. Riddell AU - Andrew J. Todd Y1 - 2015/05/13 UR - http://www.jneurosci.org/content/35/19/7626.abstract N2 - 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 characterized 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 reexamine 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 recognized, and suggests that they are likely to have several distinct roles in regulating the flow of somatosensory information through the dorsal horn. ER -