Antisense against Amyloid-β Protein Precursor Reverses Memory Deficits and Alters Gene Expression in Neurotropic and Insulin-Signaling Pathways in SAMP8 Mice

The senescence-accelerated mouse (SAMP8) strain exhibits an age-related decrease in memory accompanied by an increase in hippocampal amyloid-beta protein precursor (A beta PP) and amyloid-beta peptide (A beta). We have shown that administration of an antisense oligonucleotide against the A beta region of A beta PP (A beta PP antisense) reverses the memory deficits. The purpose of this study was to determine the effect of peripheral (IV) administration of A beta PP antisense on hippocampal gene expression. The A beta PP antisense reversed the memory deficits and altered expression of 944 hippocampal genes. Pathway analysis showed significant gene expression changes in nine pathways. These include the MAPK signaling pathway (p = 0.0078) and the phosphatidylinositol signaling pathway (p = 0.043), which we have previously shown to be altered in SAMP8 mice. The changes in these pathways contributed to significant changes in the neurotropin (p = 0.0083) and insulin signaling (p = 0.015) pathways, which are known to be important in learning and memory. Changes in these pathways were accompanied by phosphorylation changes in the downstream target proteins p70S6K, GSK3 beta, ERK, and CREB. These changes in hippocampal gene expression and protein phosphorylation may suggest specific new targets for antisense therapy aimed at improving memory.