Abstract:
Studies have shown increased amounts of essential trace metals, zinc, copper, and
iron, in human brains afflicted with Alzheimer’s disease (AD) and brains of transgenic
mouse models of AD. However, no reports have been published on the concentrations in
the amyloid plaques of an AD mouse model or the change in trace metal deposition in
amyloid-β plaques with age. This study examined the change in concentrations of trace
metals that occur with increasing age in the amyloid-β plaques in the brains of Tg2576
mice, a murine model of Alzheimer’s disease. Microprobe synchrotron x-ray
fluorescence (SXRF), a non-destructive technique that can measure all of the elements
present in the tissue at one time was used in this study. Additionally, comparisons were
also done on the concentrations of zinc, copper, and iron across the three ages in the
cortical plaques. Finally, differences in the counts of zinc, copper, iron, potassium, and
calcium between plaque tissue and non-plaque brain tissue were investigated.
The results showed a significantly lower concentration of copper in the plaques of
the cortex of the oldest age group, 22 months, compared to the youngest group of mice,
12 months. There was also an overall trend towards significantly more copper in the
cortical plaques compared to the hippocampal plaques. Finally, multi-channel analyses
(MCA) showed that there were significantly higher counts of zinc, copper, iron, and a
strong trend toward higher counts of potassium in the plaque tissue compared to the nonplaque
brain tissue in the 18 month age group.
