Fig. (7) β-endorphin in the MeA.Photographs show β-endorphin in the MeA. Each photograph represent a square of 100 × 100 µm. A: control (group 1), B: formalininjected (group 2), C: electrically stimulated to the CeA (group 3), D: sham-operated (group 4). Scale bar = 20µm.