Group housing with young mice relieves Alzheimer's disease behaviors in aging mice.

Due to the increase in human life expectancy, a higher number of individuals are experiencing age-related cognitive impairments. Therefore, it is important to investigate the methods to tackle the effects of aging.The mice were divided into the following groups: the aging mice (male, 20 months) and young mice (male, 2 months) were pairing-housed together in the same cage and lasted for at least one month (Aging-Young). The following tests were performed for the mice in different groups: Open field test, Morris water maze (MWM) test, Contextual fear conditioning test, Novel Object Recognition (NOR) test, Pain threshold test, Olfactory habituation/dishabituation test, T-maze test, Electrophysiological recordings.In this study, we housed aging and young mice together, and found that the paired housing for one-month improved the learning and memory of the aging mice. These mice exhibited better performance on the Morris water maze (MWM) test, a longer freezing duration in the contextual fear conditioning test, a higher alternation rate in the T-maze test, and an increased preference for novel objects in the novel object recognition (NOR) test. The paired housing with young mice also improved the impaired long-term potentiation (LTP) in aging mice.Our results suggest that the paired housing with young mice has beneficial effects on learning and memory of aging mice. The manipulation of the systemic environment may, therefore, provide a new strategy for aging rejuvenation.