Fig. 4.

A subset of molecularly defined projection neurons responds to noxious heat. (A, C, E, and G) Representative images of lumbar spinal cord illustrate Retrobead-labeled spinoparabrachial neurons (green) coexpressing Cck (A), Nptx2 (C), Nmb (E), or Crh (G) (red), and the Fos immediate-early gene (blue), after hindpaw stimulation with noxious heat (50 °C). Insets show enlarged examples of triple-labeled cells. (B, D, F, and H) Pie charts illustrate percentages of projection neurons that express Fos after noxious heat stimulation, percentage of projection neurons that express Cck (B), Nptx2 (D), Nmb (F), or Crh (H), as well as the percentage of projection neurons that express both Fos and respective genes. Quantification includes data from two to four mice per gene and three to six lumbar spinal cord sections per mouse. (Scale bars, 100 μm.)