Immunohistochemical localization of α7nAChR in the murine enteric nervous system. A. Confocal image of a cryostat section of the colon stained using a polyclonal antibody raised against the alpha bungarotoxin-sensitive receptor subunit α7nAChR (1:50; Abcam). The specificity of the antibody was confirmed by Western blot and demonstrating α7nAChR immunoreactivity in the adrenal medulla. B. The same section stained using an antibody to neuronal nitric oxide synthase (nNOS; Upstate Biotechnology). All α7nAChR-positive neurons express nNOS (arrow), a marker of inhibitory motorneurons in the murine colon; however, a subset of nNOS-positive neurons does not express α7nAChR (B; arrowhead). α7nAChR immunoreactivity is also displayed by immune cells in the mucosa (arrowhead). Unpublished research.