The impact of social partners: investigating mixed-strain housing effects on aging in female mice

Aging is a multifaceted process characterized by the gradual decline of physiological functions and can be modulated by various internal and external factors. While social interactions have been shown to affect behaviors and physiology in different species, the impact of social partners on aging-related phenotypes and lifespan in mice remains understudied. To address this question, we investigated various aging-related traits and lifespan in two mouse strains, C57BL/6J and BALB/c, under two different housing conditions: mixed-strain and same-strain housing. Analyses using a Generalized Linear Model revealed significant differences between the two strains in several phenotypes, including metabolic, anxiety-like, and electrocardiographic traits. However, surprisingly, housing conditions did not significantly affect most of the examined parameters, including overall lifespan. Only 3 out of 25 traits—body weight change in a metabolic cage, running wheel activity, and survival days of a quartiles of mice with middle lifespans—were influenced by housing conditions in a strain-dependent manner. Together, our study suggested a minimal influence of co-housing with social partners from different genetic backgrounds on aging-related phenotypes. This result demonstrates the feasibility of mixed housing for mouse husbandry and, more importantly, provides valuable insights for future research on the social influences on the aging process in mice.