Selenomethionine reduces the deposition of beta-amyloid plaques by modulating β-secretase and enhancing selenoenzymatic activity in a mouse model of Alzheimer's disease

Alzheimer's disease (AD) is characterized by the production of large amounts of beta-amyloid (Ab) and the accumulation of extracellular senile plaques, which have been considered to be potential targets in the treatment of AD. Selenium (Se) is a nutritionally essential trace element with known antioxidant potential and Se status has been shown to decrease with age and has a close relationship with cognitive competence in AD. Selenomethionine (Se-Met), a major reserve form of Se in organisms, has been shown in our previous study to ameliorate the decline in cognitive function, increase oxidation resistance, and reduce tau hyperphosphorylation in a triple transgenic mouse model of AD. However, it has not been reported whether Se-Met has any effects on A beta pathology in AD mice. To study the effect of Se-Met on A beta pathology and the function of selenoproteins/selenoenzymes in 3x Tg-AD mice, 3x Tg-AD mice at 8 months of age were treated with Se-Met for 3 months. Se-Met led to significantly reduced production and deposition of A beta, down-regulation of beta-secretase levels and enhanced activity of selenoenzymes as well as increased levels of Se in the hippocampus and cortex. Se-Met reduces amyloidogenic processing of amyloid precursor protein while modulating beta-secretase and selenoenzymatic activity in AD mice. These results indicate that Se-Met might exert its therapeutic effect through multiple pathways in AD.