Long‐lasting housing environment manipulation and acute loss of environmental enrichment impact BALB/c mice behaviour in multiple functional domains

Abstract

Understanding environmental influences on individuals' behaviour is challenging. Here we have investigated the housing impact of 9 weeks of enriched environment (EE) and social isolation (SI) and the impact of abrupt deprivation of EE (enrichment removal: ER) on BALB/c mice. Compared with the widely used C57BL/6 strain in research, BALB/c synthesises serotonin less efficiently due to a genetic variation and thus may potentially represent human populations at higher risk of stress‐related disorders. We assessed the effects of EE and SI by conducting a behavioural test battery and the effects of acute ER by monitoring homecage activities and social behaviour. We found that EE and SI impact BALB/c's physiological states and behavioural performances from lower to higher cognitive processes: increased body weight, increased rectal temperature, altered performance in motor and sensory tasks, the activity level in a novel environment and altered performance in tests of anxiety‐like behaviour, stress‐coping strategies and learning and memory. Furthermore, acute ER triggered stress/frustration‐like behaviour in BALB/c, with increased aggression, increased social distancing and disrupted daily/nightly activities. Our results demonstrate that long‐lasting housing manipulation such as EE and SI, impact behaviour via multilayered processes over a wide range of functional domains, and unforeseen change to a negative environment, ER, is a major stressor that causes behavioural and psychological consequences through environment–gene interactions, a model of direct relevance to human health.

The emotional impact of disrupted environmental contexts: Enrichment loss and coping profiles influence stress response recovery in Long–Evans rats

“…8,9 This enrichment-loss model corroborates previous findings that abrupt removal from an enriched environment was associated with rats' diminished motivation to explore in a radial arm maze. 10 Recently, enrichment disruption has been explored in mice noting increased aggression and social distancing, 11 as well as impaired cognition in mice exposed to both maternal immune activation and subsequent social isolation following long-term enriched environment exposure. 12 Numerous studies have confirmed that exposure to complex or enriched environments enhances neuroplasticity markers in laboratory animals 13,14 with evidence of individual differences 15,16 ; however, the pervasiveness and persistence of these effects, especially when animals are permanently relocated to more impoverished conditions, is a clinically relevant question deserving further investigation.…”

Molecular neurobiology of loss: a role for basolateral amygdala extracellular matrix

“…Here, our omics data indicate that ER does not simply reverse endpoints to SH levels, indicating that the latter does not represent a “baseline condition” to which the organism returns. Studies in mice indicate impairments in socially isolated controls, using adolescent BALB/c mice and a distinct removal protocol [ 54 ]. However, a similar study performed in Long-Evans rats yielded results more in-line with those seen here [ 55 ].…”

Maintaining a Dynamic Brain: A Review of Empirical Findings Describing the Roles of Exercise, Learning, and Environmental Enrichment in Neuroplasticity from 2017-2023

“…Moreover, Sukegawa and colleagues found that the removal of rodents from EE/EC elevated aggressive behaviors and disrupted sleeping patterns. The maladaptive behaviors were observed up to 2 weeks following enrichment removal [ 145 ].…”