Section of Experimental Animal Models, Faculty of Health and Medical Sciences, University of Copenhagen, Groennegaardsvej 15, DK-1870 Frederiksberg C, Denmark.
Novo Nordisk A/S, Novo Nordisk Park, DK-2760 Måløv, Denmark.
Physiol Behav. 2019 Jul 1;206:59-66. doi: 10.1016/j.physbeh.2019.02.022. Epub 2019 Feb 18.
Burrowing and nest building are examples of highly motivated innate behaviours in rodents. Assessments based on these behaviours can be used as non-invasive indicators of pain, distress and suffering. In this study, we investigated the effect of three stressful procedures, namely grid floor housing for 24 h, 15 min of isoflurane anaesthesia and an intraperitoneal saline injection daily for three days, on nest building and burrowing in female C57BL/6NTac mice. For burrowing, we also investigated the effect of the presence of a shelter and nesting material (standard home cage enrichment) versus no shelter and nesting material, and whether the test can be performed during normal working hours. Alongside this, we investigated the effect of grid floor, isoflurane anaesthesia and intraperitoneal injections on stress hormone level, body weight, fur status and sucrose preference. The burrowing test was found to be sensitive to 24 h grid floor housing when no shelter but only a cardboard tube was present during testing. The mice burrowed a mean of 21 g less after grid floor housing (P < .01). This change was accompanied by decreased sucrose preference (P < .01) and body weight (P < .01). 15 min of anaesthesia with isoflurane induced changes in the nest building activity test. After exposure to isoflurane the mice built less complex nests (P = .04). This was accompanied by a decrease in sucrose preference (P < .01), a decrease in body weight (P < .01), and elevated stress hormone levels (P < .01). One daily intraperitoneal injection of saline for three days did not result in changes in nest building activity (P > .01). We also found that the mice burrowed equal amount during normal working hours and prior to the dark phase, indicating that the burrowing test can be performed during normal working hours instead of prior to the dark phase (P = .62).
打洞和筑巢是啮齿动物高度自发的行为的例子。基于这些行为的评估可以作为疼痛、不适和痛苦的非侵入性指标。在这项研究中，我们研究了三种应激程序对雌性 C57BL/6NTac 小鼠筑巢和打洞行为的影响，这三种应激程序分别是：24 小时网格地板笼饲养、15 分钟异氟烷麻醉和连续三天每天腹腔注射生理盐水。对于打洞行为，我们还研究了有无庇护所和筑巢材料（标准笼内丰富环境）对打洞行为的影响，以及测试是否可以在正常工作时间进行。此外，我们还研究了网格地板、异氟烷麻醉和腹腔注射对应激激素水平、体重、皮毛状况和蔗糖偏好的影响。当测试期间只有一个纸管而没有庇护所时，打洞测试对 24 小时网格地板饲养很敏感。与网格地板饲养前相比，小鼠的打洞量平均减少了 21 克（P<0.01）。这种变化伴随着蔗糖偏好的降低（P<0.01）和体重的降低（P<0.01）。15 分钟异氟烷麻醉会引起筑巢活动测试的变化。暴露于异氟烷后，小鼠筑的巢结构更简单（P=0.04）。这伴随着蔗糖偏好的降低（P<0.01）、体重的降低（P<0.01）和应激激素水平的升高（P<0.01）。连续三天每天腹腔注射生理盐水不会导致筑巢活动的变化（P>0.01）。我们还发现，在正常工作时间和暗期前，小鼠的打洞量相同，这表明打洞测试可以在正常工作时间进行，而不是在暗期前进行（P=0.62）。
