Altered post stress coping and reward seeking behaviours in chronically stressed mice (21918)
Increasing evidence links chronic stress to the development of neuropsychiatric conditions such as depression. Maladaptive stress-coping behaviours (e.g. avoidance) and dysfunctional reward seeking behaviours (e.g. anhedonia) are often observed in depression. We aimed to investigate these stress- and reward-related behaviours in a rodent model of depression, to facilitate studies of underlying neural mechanisms.
The Unpredictable Chronic Mild Stress (UCMS) model was used, where mice are exposed to 2-4 mild stressors daily for 5 weeks to induce a depressive-like phenotype. Behaviour responses following acute stress and palatable reward consumption were measured in separate sessions.
Post-stress, UCMS exposed mice showed a significant increase in digging (p<0.0001) and a significant decrease in rearing (p<0.0001), jumps (p<0.001), and escapes (p<0.001). This suggests the UCMS mice exhibited more passive stress coping than controls. In the palatable food test, UCMS mice displayed a significantly higher number of eating bouts (p<0.05) and increased eating duration (p<0.05) compared to controls. This disturbed eating behaviour possibly suggests that chronic stress induces anxiety-like behaviours even when eating a palatable reward.
Establishing the use of acute footshock induced behaviours following UCMS to show changes in stress coping, in addition to assessing reward-related behaviours during palatable food exposure, provides a framework for future studies. Future studies will combine the use of UCMS and these behaviour assessments with approaches such as fibre photometry to investigate the specific circuitry underlying stress-induced depression and how its affected by novel treatments.