Grooming behaviour in rodents has been associated with emotional distress, especially in unfamiliar and aversive contexts. However, the biological function of grooming in such situations is still unclear. We hypothesised that particular grooming subtypes are differentially associated with the stress response. Here, we investigated the effects of an acute stress exposure on grooming and ultrasonic vocalisations (USVs) assessed on different testing contexts varying in the level of familiarity. To this aim, footshocked and non-footshocked rats were tested for 20 minutes on one of the following conditions: an unfamiliar open-field test, a familiar open-field test, and an individual home cage filled with bedding. We found that footshock stress slightly decreased complex grooming sequences while increased cephalic grooming. Stress induced a negative affective state inferred from an increase and decrease of 22-kHz and 50-kHz calls, respectively. The latter USVs correlated positively with the complex grooming subtypes. Altogether, a detailed analysis of grooming seems necessary for elucidating its diverse biological functions. Nevertheless, footshock stress and testing conditions produced weaker-than-expected effects, possibly because the time elapsed between footshocks and behavioural testing was too short for eliciting a full stress response, and because the simple footshock-chamber experience may have impeded detecting stronger effects of familiarity.

中文翻译：

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在大鼠的开放场和家笼测试中，急性应激对梳理亚型和超声波发声的影响不同

啮齿动物的美容行为与情绪困扰有关，尤其是在陌生和厌恶的环境中。然而，在这种情况下梳理毛发的生物学功能尚不清楚。我们假设特定的美容亚型与压力反应存在差异。在这里，我们调查了急性压力暴露对美容和超声发声 (USV) 的影响，评估在不同的测试环境中，熟悉程度不同。为此，在以下条件之一下对足电击和非足电击大鼠进行了 20 分钟的测试：不熟悉的露天试验、熟悉的露天试验和装有被褥的单独家笼。我们发现，足震压力略微减少了复杂的梳理序列，同时增加了头部梳理。压力分别从 22 kHz 和 50 kHz 呼叫的增加和减少中推断出一种消极的情感状态。后一种 USV 与复杂的美容亚型呈正相关。总而言之，对梳理毛发的详细分析似乎有必要阐明其多样化的生物学功能。然而，足震压力和测试条件产生的影响比预期的要弱，这可能是因为足震和行为测试之间的时间太短，无法引起完全的压力反应，并且因为简单的足震室经历可能阻碍了检测到更强烈的影响熟悉。对梳理毛发的详细分析似乎有必要阐明其多样化的生物学功能。然而，足震压力和测试条件产生的影响弱于预期，可能是因为足震和行为测试之间的时间太短，无法引发完整的压力反应，并且因为简单的足震室经验可能阻碍检测到更强烈的影响熟悉。对梳理毛发的详细分析似乎有必要阐明其多样化的生物学功能。然而，足震压力和测试条件产生的影响弱于预期，可能是因为足震和行为测试之间的时间太短，无法引发完整的压力反应，并且因为简单的足震室经验可能阻碍检测到更强烈的影响熟悉。