Induction of learning and memory dysfunction by ?-amyloid peptide fragment 25～35 in rats / 中国药理学通报

ABSTRACT

AIM To determine whether microinjection of ? amyloid peptide fragment 25～35 (A?25～35 ) into rat hippocampus induces the learning and memory dysfunction.METHODS Microinjection of A? 25～35 into hippocampus induced the rat learning and memory dysfunction. Step down test, Shuttle box test, and Morris water maze test were used to evaluate rat learning and memory function;The sections were stained with haematoxylin eosin (HE),the amyloid deposits were detected using Congo Red and silver.RESULTS The latency of A? 25～35 treated rats shortened,the stimulating time prolonged,and the numbers of errors increased in the step down test;Shuttle box test showed that A? 25～35 caused the latency and numbers of active escape reduction and the numbers of passive avoidance increase; Also in morris water maze, A?25 35 induced an impairment in rat spatial resolution; In A? 25～35 treated group, a significant decrease in the numbers of neurons in cortex and hippocampus,a massive glial reaction and neurophilic phenomenon were detected by HE staining; the positive vascular amyloidosis by Congo red and fibrils by Ag staining were also observed.CONCLUSION Microinjection of A? 25～35 into rat hippocampus may induce the learning and memory dysfunction and pathological changes which were similar to that found in Alzheimers disease (AD) brain.