Figure 2.

Copper is enriched in the mouse locus coeruleus. a, the diagram of a mouse brain (a sagittal view); the line shows the location where coronal sections were taken. The red dot represents the LC. b, representative tiled confocal image of the coronal section immunostained for DBH. Regions with high expression of DBH indicate LC (circles). c, XFM images for metals. The map of phosphate, which has stable levels in cells, is used as a control. The enrichment of Cu in the LC region is evident from the lighter color. Other metals (potassium (K), phosphorus (P), and zinc (Zn)) were not elevated in the LC and are shown to illustrate the specificity of Cu enrichment. d, consecutive brain sections were used to verify that high Cu levels occur in the LC; one section was imaged using XFM and the adjacent section was immunostained for DBH. Left, XFM image shows high Cu fluorescence (indicated by a light color) in ventricles and in the LC. Right, immunostaining of DBH confirms high Cu in the LC. e, left, a schematic illustrating the areas (in turquoise) that were used for comparison of Cu levels: LC (circled) and the region outside of LC (the pons). Right, Cu/Zn ratio in the LC and pons regions (1.01 ± 0.08 and 0.33 ± 0.01, respectively; n = 3; p = 0.001).