Proteomic identification of less oxidized brain proteins in aged senescence-accelerated mice following administration of antisense oligonucleotide directed at the Aβ region of amyloid precursor protein

Amyloid β-peptide (Aβ) is the major constituent of senile plaques, a pathological hallmark of Alzheimer's disease (AD) brain. It is generally accepted that Aβ plays a central role in the pathophysiology of AD. Aβ is released from cells under entirely normal cellular conditions during the internalization and endosomal processing of amyloid precursor protein (APP). However, accumulation of Aβ can induce neurotoxicity. Our previous reports showed that decreasing the production of Aβ by giving an intracerebroventricular injection of a 42-mer phosphorothiolated antisense oligonucleotide (AO) directed at the Aβ region of the APP gene reduces lipid peroxidation and protein oxidation and improves cognitive deficits in aged senescence-accelerated mice prone 8 (SAMP8) mice. In order to investigate how Aβ level reduction improves learning and memory performance of SAMP8 mice through reduction of oxidative stress in brains, we used proteomics to identify the proteins that are less oxidized in 12-month-old SAMP8 mice brains treated with AO against the Aβ region of APP (12 mA) compared to that of the age-control SAMP8 mice. We found that the specific protein carbonyl levels of aldoase 3 (Aldo3), coronin 1a (Coro1a) and peroxiredoxin 2 (Prdx2) are significantly decreased in the brains of 12 mA SAMP8 mice compared to the age-controlled SAMP8 treated with random AO (12 mR). We also found that the expression level of α-ATP synthase (Atp5a1) was significantly decreased, whereas the expression of profilin 2 (Pro-2) was significantly increased in brains from 12 mA SAMP8 mice. Our results suggest that decreasing Aβ levels in aged brain in aged accelerated mice may contribute to the mechanism of restoring the learning and memory improvement in aged SAMP8 mice and may provide insight into the role of Aβ in the memory and cognitive deficits in AD.