Cognitive deficits in single App knock-in mouse models

Transgenic mouse models of Alzheimer's disease (AD) with nonphysiologic overexpression of amyloid precursor protein (APP) exhibit various unnatural symptoms/dysfunctions. To overcome this issue, mice with single humanized App knock-in (KI) carrying Swedish (NL), Beyreuther/Iberian (F), and Arctic (G) mutations in different combinations were recently developed. The validity of these mouse models of AD from a behavioral viewpoint, however, has not been extensively evaluated. Thus, using an automated behavior monitoring system, we analyzed various behavioral domains, including executive function, and learning and memory. The App-KI mice carrying NL-G-F mutations showed clear deficits in spatial memory and flexible learning, enhanced compulsive behavior, and reduced attention performance. Mice carrying NL-F mutations exhibited modest abnormalities. The NL-G-F mice had a greater and more rapid accumulation of Aβ deposits and glial responses. These findings reveal that single pathologic App-KI is sufficient to produce deficits in broad cognitive domains and that App-KI mouse lines with different levels of pathophysiology are useful models of AD.