Aging affects emotional, cognitive, and social functions, increasing susceptibility to neuropsychiatric conditions. C57BL/6 mice are commonly used to study aging mechanisms, yet differences between C57BL/6J and C57BL/6N substrains remain underexplored. This study compared aging-related behavioral changes in these substrains. Aging reduced exploratory activity and heightened anxiety in C57BL/6J, but not C57BL/6N, mice. Conversely, aging reduced social novelty preference in C57BL/6N, but not C57BL/6J, mice. Male mice of both substrains exhibited increased female urine sniffing with age. These findings highlight substrain-specific aging effects, underscoring the importance of substrain selection in behavioral studies of aged mice for drug development.

C57BL/6J and C57BL/6N mice show distinct aging-associated behavioral alterations