Environmental enrichment induces depressive- and anxiety-like behaviors in male Balb/C mice

Depression and anxiety disorders are prevalent neuropsychiatric conditions worldwide that impose substantial economic and social burdens worldwide. Environmental enrichment (EE) has been employed to investigate how the environment can influence these disorders. While EE is known to mitigate depressive and anxiety phenotypes across various mouse strains, the Balb/C strain exhibits greater sensitivity to different environmental stimuli. In this study, we aimed to assess the long-term effects of EE introduced after weaning on emotional behaviors in adulthood. Balb/C mice were weaned on postnatal day (PND) 21 and exposed to chronic EE for 3, 12, or 24 hours daily until PND 66. Depressive- and anxiety-like behaviors were assessed using the open field, elevated plus maze, and tail suspension tests, along with measurements of corticosterone plasma levels. EE exposure induced emotional dysregulation, evidenced by an increase in anxiety- and depressive-like behaviors. Shorter length of EE (3 h) had less impact on these behaviors compared to longer periods (12 and 24 h). These findings highlight the need for caution when employing the Balb/C strain in EE models, particularly in studies exploring emotional behaviors.