科研之友
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摘要
Laboratory mice housed at typical temperatures and provided with crinkled paper nesting material build fully enclosed nests, increasing welfare, and reducing cold stress, but complicating daily animal observations by care staff. Anecdotal reports by animal care staff indicate that ill mice are not found within the nest and do not nest build. We hypothesized that both nest shape and whether or not ill mice were found outside the nest could be used as tools to identify ill mice. Forty two female C57BL/6NCrl mice were provided log of nesting material and assigned to a social treatment of either solitary or group housing. Lipopolysaccharide (LPS) injected intraperitoneally at 1 mg/kg was used to induce malaise in 0, 1, 2, or 3 mice/cage; all others received saline. Prior to the study, mice were habituated to handling and injections with positive reinforcement. In order to blind the nest scorer to treatment novel, but experienced, handlers administered the experimental injections. Nest score, number of mice in the nest, and anhedonia measured by sugared cereal consumption were recorded at the following time points: baseline, cage change, saline injection, injection, and injection + cage change and data were analyzed using GLMs with post-hoc contrasts. The number of mice observed outside the nest was not affected by any treatment. Nest score was not significantly altered in group housed mice but LPS-injected solitary mice had significantly lower nest scores than saline-injected solitary mice at the injection + cage change time point. Saline-injected mice also had a significant reduction in nest score from baseline at injection+ cage change. It is likely that receiving the injection from novel handlers were likely the cause for this alteration, yielding the unexpected result that nest building in mice is affected by a novel handler. LPS-injected mice, regardless of social treatment, ate approximate to 2 g less sugared cereal per mouse at both injection and injection + cage change time points compared to their baseline cereal consumption and saline-injected mice at the same time points. Group housing appears to mask changes in nest score if other cage residents are healthy and acutely ill individuals were not observed to have a location bias, in or out of the nest, after LPS injection. However, a reduction in nest score has the potential to be a useful tool to identify acute illness after cage change in solitary mice. Changes in nest complexity may be useful to identify illness earlier for general husbandry and welfare purposes and may be a more robust tool in chronic, rather than acute, disease models.
- 出版日期2016-7
