Mixed housing with DBA/2 mice induces stress in C57BL/6 mice: implications for interventions based on social enrichment

Abstract

Several behavioral interventions, based on social enrichment and observational learning are applied in treatment of neuropsychiatric disorders. However, the mechanism of such modulatory effect and the safety of applied methods on individuals involved in social support need further investigation. We took advantage of known differences between inbred mouse strains to reveal the effect of social enrichment on behavior and neurobiology of animals with different behavioral phenotypes. C57BL/6 and DBA/2 female mice displaying multiple differences in cognitive, social, and emotional behavior were group-housed either in same-strain or in mixed-strain conditions. Comprehensive behavioral phenotyping and analysis of expression of several plasticity- and stress-related genes were done to measure the reciprocal effects of social interaction between the strains. Contrary to our expectation, mixed housing did not change the behavior of DBA/2 mice. Nevertheless, the level of serum corticosterone and the expression of glucocorticoid receptor Nr3c1 in the brain were increased in mixed housed DBA/2 as compared with those of separately housed DBA/2 mice. In contrast, socially active C57BL/6 animals were more sensitive to the mixed housing, displaying several signs of stress: alterations in learning, social, and anxiety-like behavior and anhedonia. These behavioral impairments were accompanied by the elevated serum corticosterone and the reduced expression of Nr3c1, as well as the elevated Bdnf levels in the cortex and hippocampus. Our results demonstrate the importance of social factors in modulation of both behavior and the underlying neurobiological mechanisms in stress response, and draw attention to the potential negative impact of social interventions for individuals involved in social support.

High temporal resolution gastric emptying breath tests in mice

“…There are well known differences in immune and physiological processes between C57Bl/6J and Balb/cJ mice, including stress that is well known to modulate gastric emptying . Blood corticosterone levels were tested as a quantitative measure of stress from three groups of mice: baseline C57Bl/6J mice that did not undergo gastric emptying and C57Bl/6J and Balb/cJ mice that underwent gastric emptying.…”

Trigeminal Inflammatory Compression (TIC) injury induces chronic facial pain and susceptibility to anxiety-related behaviors

“…First, all of our animals were male C57Bl/6 mice. C57Bl/6 mice were chosen for their moderate levels of anxiety-like behavior ((Belzung, 2001, Belzung and Griebel, 2001, Kulesskaya et al, 2014, Kulesskaya and Voikar, 2014) In order to collect more consistent results, no females or other strains were tested in this study. However, future studies should be conducted to observe the behavior of different species or gender of mice with TIC injury since facial neuropathic pain in humans occurs preferentially in females (Rauhala et al, 2000, Macfarlane et al, 2001, Macfarlane et al, 2002).…”

Observational fear behavior in rodents as a model for empathy

“…It has been well known that different inbred mouse strains show different emotional responses to social stress, and such differences have been attributed to genetic differences of the strains . We previously surveyed multiple inbred mouse strains and found that the vicarious freezing response was highly variable among different strains.…”