Cage migration and memory: investigating the impact of varied cage sizes on memory function in Swiss mice

Abstract

BACKGROUND AND AIM: Diverse cage sizes have been implicated in the alteration of pain sensitivity and inflammation parameters in animal-based experiments. Sparse information is available on the effect of exposure to different cage sizes on memory in animal studies. This study thus aimed to investigate the effect of varied cage size exposure on memory. METHODOLOGY: Twelve adult male Swiss mice (29-34 g) divided into two groups (n=6) were used for this study, comprising a Control group (stationary cage) and a Test group (migrated cage). The cage-migrated mice were exposed daily to various cage sizes typically used in Nigerian laboratories for 30 days. In contrast, the cage-stationed mice were daily exposed to new but the same size and shape cage. After 30 days of exposure, memory functions were assessed in the animals using memory-related behavioural paradigms (such as novel object recognition test), acetylcholinesterase activity and histological evaluation. RESULTS: The results showed no significant difference in the recognition and spatial memory of cage-migrated animals compared to its cage stationed counterparts. The brain acetylcholinesterase activity significantly (p < 0.05) decreased in cage-migrated mice compared to cage-stationed animals but there was no difference in plasma acetylcholinesterase activity in both groups. Also, histological evaluation of all regions of the hippocampus in both groups of animals did not show any significant difference. Though cornu ammonis regions appeared to be enlarged in cage migrated animals compared to cage stationed. CONCLUSION: Repeated exposure of experimental mice to varied cage sizes could selectively decrease brain acetylcholinesterase activity without affecting the animals’ memory.