Fig. 1.

Neurotransmitter heterogeneity of dorsal horn neurons. Fluorescent in situ hybridization labelling for VGLUT2 (magenta), GAD1 (green), and VGAT (white) shows excitatory interneurons (magenta) outnumber inhibitory interneurons (green and white, or white only) in laminae I–III. VGLUT2-expressing interneurons are common in laminae I–III. Inhibitory interneurons can be split into three subpopulations based on their neurotransmitter content: those that express GABA, those that express glycine, and those that express both GABA and glycine. In this figure, inhibitory interneurons that only express GABA, and those likely to co-express both GABA and glycine, show co-expression for both GAD1 and VGAT (green and white, respectively) and are common in laminae I–III, whereas cells that express only glycine are common in lamina IV (insets, yellow asterisks). AM Bell, AJ Todd, and DI Hughes, unpublished observations