MARBEC, Univ. Montpellier, CNRS, Ifremer, IRD, Palavas-les-flots, France; Laboratoire Ressources Halieutiques, Ifremer, Place Gaby Coll, F-17137 L'Houmeau, France.
MARBEC, Univ. Montpellier, CNRS, Ifremer, IRD, Palavas-les-flots, France.
Physiol Behav. 2019 Aug 1;207:76-85. doi: 10.1016/j.physbeh.2019.04.020. Epub 2019 Apr 29.
Coping styles consist of a coherent set of individual physiological and behavioral differences in stress responses that are consistent across time and context. Such consistent inter-individual differences in behavior have already been shown in European sea bass (Dicentrarchus labrax), but the associated mechanisms are still poorly understood. Here, we combine physiological measurements with individual behavioral responses in order to characterize coping styles in fish. Fish were tagged and placed in a tank for group risk-taking tests (GRT) at 8 months of age to evaluate boldness using the proxy latency of leaving a sheltered area towards an open area. A subsample of these fish were individually challenged 16 months later using an open field test (OFT), in which the boldness was assessed after being placed in a shelter within an open arena. Latency to exit the shelter, time spent in the shelter, and distance travelled were recorded for this purpose. The blood and brain were then collected to evaluate plasma cortisol concentration and neurotransmitter levels (dopamine, norepinephrine, serotonin, and related metabolites), as well as brain transcription of key genes involved in stress axis regulation (gr1, gr2, mr, crf), neurogenesis (neurod1, neurod2, pcna), and neuronal development (egr1). Fish acting bolder in the GRT were not necessarily those acting bolder in the OFT, highlighting the relatively low consistency across different types of tests performed with a 16-months interval. There was, however, a significant correlation between stress markers and boldness. Indeed, mRNA levels of mr, crf, gr2, egr1, and neurod2, as well as norepinephrine levels were higher in shy than bold fish, whereas brain serotonergic activity was lower in shy fish. Overall, our study highlights the fact that boldness was not consistent over time when testing context differed (group vs. alone). This is in agreement with previous literature suggesting that social context play a key role in boldness measurement and that the particular life history of each individual may account in shaping the personality fate of a fish.
应对方式由个体在压力反应中的一系列生理和行为差异组成，这些差异在时间和环境上具有一致性。这种行为上的个体间一致性差异已经在欧洲鲈鱼（Dicentrarchus labrax）中得到了证实，但相关机制仍知之甚少。在这里，我们将生理测量与个体行为反应相结合，以描述鱼类的应对方式。这些鱼在 8 个月大时被标记并放入一个水箱中进行群体冒险测试（GRT），以通过离开遮蔽区进入开阔区的时间来评估其大胆程度。这些鱼的一部分在 16 个月后被单独用一个开阔场地测试（OFT）进行挑战，在此测试中，在开放场地的遮蔽区中放置鱼后，评估其大胆程度。为此，记录了离开遮蔽区的潜伏期、在遮蔽区停留的时间和行进的距离。然后收集血液和大脑，以评估血浆皮质醇浓度和神经递质水平（多巴胺、去甲肾上腺素、血清素和相关代谢物），以及参与应激轴调节的关键基因（gr1、gr2、mr、crf）、神经发生（neurod1、neurod2、pcna）和神经元发育（egr1）的脑转录。在 GRT 中表现出更大胆的鱼不一定在 OFT 中表现出更大胆，这突出了在相隔 16 个月进行不同类型测试时相对较低的一致性。然而，应激标志物和大胆之间存在显著相关性。事实上，mr、crf、gr2、egr1 和 neurod2 的 mRNA 水平以及去甲肾上腺素水平在害羞鱼中较高，而在害羞鱼中脑血清素活性较低。总的来说，我们的研究强调了一个事实，即在测试环境不同（群体与单独）时，大胆程度不会随时间保持一致。这与之前的文献一致，即社会环境在大胆测量中起着关键作用，并且每个个体的特定生活史可能会影响鱼类个性的形成。
