Effects of 8-residue ß sheet breaker peptides on aged Aß40-induced memory impairment and Aß40 expression in rat brain and serum following intraamygdaloid injection.

Abstract

Amyloidß-protein (Aß) assembly into toxic fibrillar structures is seminal in development of senile plaques, the pathological hallmark of Alzheimer's disease. Blocking this process could have a therapeutic value. ß-sheet breaker peptides (ßSBP) decrease Aß fibrillogenesis and neurotoxicity by preventing or dissolving misfolded Aß aggregates. The present study investigated the effects of ßSBPs on Aß40-related neuropathology, memory impairment in 8-armed radial maze and expression of Aß40 in brain and serum. Aß40 was injected into amygdaloid nucleus followed 8 days later by octapeptideßSBPs 15-22, 16-23 and 17-24. Aß40 was detected not only in amygdala, but also in serum. Aß40 induced cellular changes in amygdala and additionally in hippocampus. Aß40 decreased correct choices, whereas increased errors (both number of arms revisited and total number of revisits) and latency of completing the maze test. The ßSBPs decreased Aß40-induced pathological changes, memory impairment and Aß40 expression in serum. The ßSBP15-22 distinctively decreased the total errors on day 14. The present results show that octapeptide ßSBPs corrected Aß40-induced memory impairment, and support investigation of ßSBPs as a promising treatment of diseases characterized by neurodegeneration and memory impairment such as Alzheimer's disease.