Fig. (9) Dynorphin A observed in the lateral PAG.Photographs show dynorphin A observed in the lateral PAG. Each photograph represents a square of 100 × 100µm. A: control (group 1), B: formalin-injected (group 2), C: electrically stimulated to the CeA (group 3), D: sham-operated (group 4). Scale bar = 20 µm.