Social instigation and repeated aggressive confrontations in male Swiss mice: analysis of plasma corticosterone, CRF and BDNF levels in limbic brain areas

Abstract Introduction: Agonistic behaviors help to ensure survival, provide advantage in competition, and communicate social status. The resident-intruder paradigm, an animal model based on male intraspecific confrontations, can be an ethologically relevant tool to investigate the neurobiology of aggressive behavior. Objectives: To examine behavioral and neurobiological mechanisms of aggressive behavior in male Swiss mice exposed to repeated confrontations in the resident intruder paradigm. Methods: Behavioral analysis was performed in association with measurements of plasma corticosterone of mice repeatedly exposed to a potential rival nearby, but inaccessible (social instigation), or to 10 sessions of social instigation followed by direct aggressive encounters. Moreover, corticotropin-releasing factor (CRF) and brain-derived neurotrophic factor (BNDF) were measured in the brain of these animals. Control mice were exposed to neither social instigation nor aggressive confrontations. Results: Mice exposed to aggressive confrontations exhibited a similar pattern of species-typical aggressive and non-aggressive behaviors on the first and the last session. Moreover, in contrast to social instigation only, repeated aggressive confrontations promoted an increase in plasma corticosterone. After 10 aggressive confrontation sessions, mice presented a non-significant trend toward reducing hippocampal levels of CRF, which inversely correlated with plasma corticosterone levels. Conversely, repeated sessions of social instigation or aggressive confrontation did not alter BDNF concentrations at the prefrontal cortex and hippocampus. Conclusion: Exposure to repeated episodes of aggressive encounters did not promote habituation over time. Additionally, CRF seems to be involved in physiological responses to social stressors.

摘要 引言：攻击行为有助于保障生存、在竞争中获取优势并传递社会地位。基于雄性种内对抗的动物模型——居住者-入侵者范式（resident-intruder paradigm），可作为研究攻击行为神经生物学的行为生态学相关工具。研究目的：探究在居住者-入侵者范式中反复暴露于对抗情境的雄性瑞士小鼠，其攻击行为的行为学与神经生物学机制。研究方法：本研究对两类小鼠开展行为学分析并检测其血浆皮质酮水平：一类为反复暴露于「附近存在不可接触的潜在竞争者（社会激发，social instigation）」情境的小鼠，另一类为先经历10次社会激发、随后开展直接攻击对抗的小鼠。此外，本研究还检测了上述动物脑组织中的促肾上腺皮质激素释放因子（corticotropin-releasing factor，CRF）与脑源性神经营养因子（BNDF）水平。对照组小鼠既不接受社会激发，也不经历攻击对抗。研究结果：经历攻击对抗的小鼠，在首次与最后一次实验中，均表现出典型物种特异性的攻击与非攻击行为模式。此外，与仅接受社会激发的小鼠相比，反复经历攻击对抗的小鼠血浆皮质酮水平升高。在10次攻击对抗实验后，小鼠的海马体CRF水平呈现非显著性下降趋势，且该水平与血浆皮质酮水平呈负相关。与之相反，反复开展社会激发或攻击对抗实验，均未改变小鼠前额叶皮层与海马体的脑源性神经营养因子（BNDF）浓度。研究结论：反复经历攻击对抗事件并未随时间推移产生习惯化效应。此外，CRF似乎参与了针对社会应激源的生理应答。

搜集汇总

背景与挑战

背景概述

该数据集聚焦于雄性瑞士小鼠在反复社会挑衅和攻击性对抗中的行为及神经生物学反应，特别关注血浆皮质酮、CRF和BDNF水平的变化。研究结果表明，反复攻击性对抗不会随时间产生习惯化，且CRF参与了对社会应激源的生理反应。