Fig. 1. Adenosine A1 receptor immunoreactivity in the thoracic spinal cord. A, Low magnification of staining obtained with the A1 receptor antibody raised in rabbit (gift from Dr. Mike Yates, Leeds University) in the thoracic spinal cord. Immunoreactivity was visualized with diaminobenzidine. Labeling was observed throughout the spinal cord. Even at low magnification, the IML is clearly seen as heavily stained. Staining is also dense around the central canal (CC), the dorsal horn (DH), and the ventral horn (VH). B, Low magnification of staining obtained with the A1 receptor antibody raised in goat (Santa Cruz Biotechnology), prepared identically to the material inA, except for the primary antibody. Note that the pattern of staining is almost identical, with the IML and ventral horn being particularly prominent. C, High magnification of the IML. Staining was a compact collection of punctate structures covering the IML adjacent to the white matter (WM). The arrow indicates one such punctate structure. D, In the vicinity of the central canal, labeling could be observed in the somata and dendrites of neurons (arrows), as well as presumptive fibers.E, In the dorsal horn, staining of fibers was dense in lamina II, and labeled neuronal somata could also be observed in laminas II and III (arrows). F, In the ventral horn, labeled fibers, somata, and dendrites of large neurons (arrow) were observed.