Chronic gut inflammation changes anxiodepressive and coping behaviour in female mice

Abstract

Major depressive disorder (MDD) is a complex condition, with increasing evidence supporting the existence of an inflammation-associated subtype. People with inflammatory bowel diseases (IBDs), which cause chronic gut inflammation, experience disproportionately high rates of anxiety and depression - females with IBD appear to be particularly susceptible. It remains unclear why females are at higher risk. This is partly because most preclinical research to date has used male rodents to study how chronic inflammation affects the brain. In this study I investigated the impact of chronic gut inflammation on anxiety-like and threat-coping behaviours in female mice. The treatment group exhibited changes to threat coping behaviours and shock reactivity in the shock probe defensive burying test, and changes in threat coping behaviours in the forced swim test when compared to controls. However, there were no significant differences observed between the groups on tests of anxiety-like behaviour in the elevated plus maze and open field task. The findings suggest that chronic gut inflammation selectively alters coping behaviour without inducing general increases in anxiety-like behaviour. To the author’s knowledge, this is the first study to report behavioural changes in the shock probe defensive burying task and forced swim test in female mice exposed to chronic DSS treatment. This work highlights the importance of sex-specific research and the use of nuanced behavioural paradigms in preclinical models to better understand the effects of chronic inflammation on anxiodepressive behaviours. Overall, the novel findings contribute to a growing body of literature linking gut inflammation to alterations in central nervous system function and behaviour in a female murine model.