| Abstract No.: | A-C1085 |
| Country: | Canada |
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| Title: | INVESTIGATION OF A SEPARATION-BASED MODEL OF DEPRESSION IN FEMALE C57BL/6J MICE |
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| Authors/Affiliations: | 1 Alison Martin*; 1 Rhian Gunn; 1 Richard Brown;
1 Dalhousie University, Halifax, NS, Canada
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| Content: | Objectives: Our aim was to develop a separation-based model of depression in mice. Based on observations in our lab, we hypothesized that when group-housed mice were separated from their cage-mates, they would show behavioural signs of depression. In prarie voles, prolonged social isolation produces depression-like behaviours (Grippo, A.J. et al., 2007, Psychoneuroendocrinology, 32, 966-980) and long-term social isolation causes stress and anxiety-like behaviour in female CD-1 mice (Palanza, P., 2001, Neurosci. Biobehav. Rev., 25, 219-233).
Materials and methods: We tested 3 groups of C57BL/6J female mice: 12 mice were housed individually from 8 weeks of age (isolated condition), 12 mice were housed in groups and then separated at 23 weeks of age (separated condition), and 12 mice were housed in groups (grouped condition). Between 24 and 27 weeks of age, mice were given a battery of tests for depression-like behaviours, which included the light/dark box (anxiety), forced swim (behavioural despair), tail suspension (behavioural despair), auditory startle response (startle), prepulse inhibition (sensorimotor gating), and cued and context conditioning (fear learning and memory). Mice were weighed one week before testing began as well as each day of testing.
Results: There was a significant difference in body weight as isolated and separated mice weighed more than group housed mice. In the light/dark box, grouped mice were more active than isolated mice and separated mice showed a reduction in activity. In tail suspension, isolated mice and separated mice showed a higher number of bouts of immobility than grouped mice. Isolated mice showed the highest percent time spent immobile in the forced swim test, while grouped mice showed the least. The percent time immobile of separated mice in the forced swim test was greater than group housed mice but less than isolated mice Both grouped and isolated mice showed a much larger startle response than separated mice and all groups showed a reduced startle response following a warning prepulse. There were no differences between groups in learning or memory tests of cued or context fear conditioning.
Conclusion: These preliminary results suggest that separation from grouped housing induces depression-like behaviour in mice as shown by weight gain, the tail suspension test and the forced swim test. Overall, separation of mice from cage-mates resulted in changes in four of the tests used to asses depression-like behaviour. Further development of the mouse separation model of depression will examine age and sex differences across mouse strains and the sensitivity of different behavioural tests of depression. |
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