Research Summary: Prolonged Depression-Like Behavior Caused by Immune Challenge: Influence of Mouse Strain and Social Environment


Immune challenge by bacterial lipopolysaccharide (LPS) causes short-term
behavioral changes indicative of depression. The present study sought to explore
whether LPS is able to induce long-term changes in depression-related behavior
and whether such an effect depends on mouse strain and social context. LPS (0.83
mg/kg) or vehicle was administered intraperitoneally to female CD1 and C57BL/6
mice that were housed singly or in groups of 4. Depression-like behavior was
assessed with the forced swim test (FST) 1 and 28 days post-treatment.
Group-housed CD1 mice exhibited depression-like behavior 1 day post-LPS, an
effect that leveled off during the subsequent 28 days, while the behavior of
singly housed CD1 mice was little affected. In contrast, singly housed C57BL/6
mice responded to LPS with an increase in depression-like behavior that was
maintained for 4 weeks post-treatment and confirmed by the sucrose preference
test. Group-housed C57BL/6 mice likewise displayed an increased depression-like
behavior 4 weeks post-treatment. The behavioral changes induced by LPS in
C57BL/6 mice were associated with a particularly pronounced rise of
interleukin-6 in blood plasma within 1 day post-treatment and with changes in
the dynamics of the corticosterone response to the FST. The current data
demonstrate that immune challenge with LPS is able to induce prolonged
depression-like behavior, an effect that depends on genetic background (strain).
The discovery of an experimental model of long-term depression-like behavior
after acute immune challenge is of relevance to the analysis of the epigenetic
and pathophysiologic mechanisms of immune system-related affective


Publisher: Public Library of Science

Date Published: 6-June-2011

Author(s): Painsipp E., Köfer M., Sinner F., Holzer P.


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