Department of Animal Science, Purdue University, West Lafayette, Indiana, United States of America.
Department of Chemistry, Indiana University, Bloomington, Indiana, United States of America.
PLoS One. 2022 Nov 2;17(11):e0276844. doi: 10.1371/journal.pone.0276844. eCollection 2022.
Home cage aggression causes poor welfare in male laboratory mice and reduces data quality. One of the few proven strategies to reduce aggression involves preserving used nesting material at cage change. Volatile organic compounds from the nesting material and several body fluids not only correlate with less home cage aggression, but with more affiliative allo-grooming behavior. To date, these compounds have not been tested for a direct influence on male mouse social behavior. This study aimed to determine if 4 previously identified volatile compounds impact home cage interactions. A factorial design was used with cages equally split between C57BL/6N and SJL male mice (N = 40). Treatments were randomly assigned across cages and administered by spraying one compound solution on each cage's nesting material. Treatments were refreshed after day 3 and during cage change on day 7. Home cage social behavior was observed throughout the study week and immediately after cage change. Several hours after cage change, feces were collected from individual mice to measure corticosterone metabolites as an index of social stress. Wound severity was also assessed after euthanasia. Measures were analyzed with mixed models. Compound treatments did not impact most study measures. For behavior, SJL mice performed more aggression and submission, and C57BL/6N mice performed more allo-grooming. Wound severity was highest in the posterior region of both strains, and the middle back region of C57BL/6N mice. Posterior wounding also increased with more observed aggression. Corticosterone metabolites were higher in C57BL/6N mice and in mice treated with 3,4-dimethyl-1,2-cyclopentanedione with more wounding. These data confirm previous strain patterns in social behavior and further validates wound assessment as a measure of escalated aggression. The lack of observed treatment effects could be due to limitations in the compound administration procedure and/or the previous correlation study, which is further discussed.
笼内攻击行为会降低雄性实验小鼠的福利并降低数据质量。减少攻击行为的少数有效策略之一是在更换笼子时保留使用过的筑巢材料。筑巢材料和几种体液中的挥发性有机化合物不仅与笼内攻击行为减少相关，还与更多的社交性互理毛行为相关。迄今为止，这些化合物尚未被测试是否会直接影响雄性小鼠的社交行为。本研究旨在确定之前鉴定的 4 种挥发性化合物是否会影响雄性小鼠的笼内互动。采用因子设计，将 C57BL/6N 和 SJL 雄性小鼠的笼子平均分为两组（N=40）。处理方案在笼子间随机分配，并通过向每个笼子的筑巢材料喷洒一种化合物溶液来实施。在第 3 天和第 7 天更换笼子时进行处理更新。在整个研究周内以及更换笼子后立即观察笼内社交行为。更换笼子数小时后，从个体小鼠中收集粪便以测量皮质酮代谢物作为社交压力的指标。安乐死后还评估了伤口严重程度。使用混合模型分析测量结果。化合物处理并未影响大多数研究指标。就行为而言，SJL 小鼠表现出更多的攻击和屈服行为，而 C57BL/6N 小鼠表现出更多的社交性互理毛行为。两种品系的后背部区域以及 C57BL/6N 小鼠的中背部区域的伤口严重程度最高。随着观察到的攻击行为增加，后背部的伤口也会增加。C57BL/6N 小鼠的皮质酮代谢物水平更高，并且在接受 3,4-二甲基-1,2-环戊二酮处理的小鼠中，伤口越多，皮质酮代谢物水平越高。这些数据证实了先前在社交行为方面的品系模式，并进一步验证了伤口评估作为衡量攻击性升级的一种方法。未观察到处理效果可能是由于化合物给药程序和/或之前的相关性研究存在局限性，进一步对此进行了讨论。
