Laboratory of Experimental Neuropsychobiology, Department of Biochemistry and Molecular Biology, Natural and Exact Sciences Center, Federal University of Santa Maria, 1000 Roraima Avenue, Santa Maria, RS 97105-900, Brazil; Graduate Program in Biological Sciences: Toxicological Biochemistry, Federal University of Santa Maria, 1000 Roraima Avenue, Santa Maria, RS 97105-900, Brazil.
Laboratory of Experimental Neuropsychobiology, Department of Biochemistry and Molecular Biology, Natural and Exact Sciences Center, Federal University of Santa Maria, 1000 Roraima Avenue, Santa Maria, RS 97105-900, Brazil; Graduate Program in Biological Sciences: Toxicological Biochemistry, Federal University of Santa Maria, 1000 Roraima Avenue, Santa Maria, RS 97105-900, Brazil.
Behav Processes. 2023 Aug;210:104912. doi: 10.1016/j.beproc.2023.104912. Epub 2023 Jul 3.
Anxiety is a protective behavior when animals face aversive conditions. The open field test (OFT) is used to assess the spatio-temporal dynamics of exploration, in which both homebase formation and recognition of environmental cues may reflect habituation to unfamiliar conditions. Because emotional- and affective-like states influence exploration patterns and mnemonic aspects, we aimed to verify whether the exploratory behaviors of two zebrafish populations showing distinct baselines of anxiety differ in two OFT sessions. Firstly, we assessed the baseline anxiety-like responses of short fin (SF) and leopard (LEO) populations using the novel tank test (NTT) and light-dark test (LDT) in 6-min trials. Fish were later tested in two consecutive days in the OFT, where the spatial occupancy and exploratory profile were analyzed for 30 min. In general, LEO showed pronounced diving behavior and scototaxis in the NTT and LDT, respectively, in which an "anxiety index" corroborated their exacerbated anxiety-like behavior. In the OFT, the SF population spent less time to establish the homebase in the 1st trial, while only LEO showed a markedly reduction in the latency to homebase formation in the 2nd trial. Both locomotion and homebase-related activities were decreased in the 2nd trial, in which animals also revealed increased occupancy in the center area of the apparatus. Moreover, we verified a significant percentage of homebase conservation for both populations, while only SF showed reduced the number of trips and increased the average length of trips. Principal component analyses revealed that distinct factors accounted for total variances between trials for each population tested. While homebase exploration was reduced in the 2nd trial for SF, an increased occupancy in the center area and hypolocomotion were the main factors that contribute to the effects observed in LEO during re-exposure to the OFT. In conclusion, our novel data support the homebase conservation in zebrafish subjected to independent OFT sessions, as well as corroborate a population-dependent effect on specific behavioral parameters related to exploration.
焦虑是动物面对厌恶条件时的一种保护行为。旷场测试（OFT）用于评估探索的时空动态，其中，家域的形成和环境线索的识别都可能反映出对陌生环境的习惯化。由于情绪和情感状态会影响探索模式和记忆方面，我们旨在验证两种表现出不同焦虑基线的斑马鱼种群在两次 OFT 测试中的探索行为是否存在差异。首先，我们使用新鱼缸测试（NTT）和明暗测试（LDT）在 6 分钟的试验中评估短鳍（SF）和豹纹（LEO）种群的基线焦虑样反应。然后，鱼在 OFT 中连续两天进行测试，分析 30 分钟的空间占用和探索情况。一般来说，LEO 在 NTT 和 LDT 中分别表现出明显的潜水行为和避光行为，其中“焦虑指数”证实了它们加剧的焦虑样行为。在 OFT 中，SF 种群在第一次试验中建立家域的时间较短，而只有 LEO 在第二次试验中建立家域的潜伏期明显缩短。第二次试验中，无论是运动还是与家域相关的活动都减少了，动物在仪器中心区域的占有率也增加了。此外，我们验证了两个种群的家域保留率都有显著百分比，而只有 SF 减少了出行次数，增加了出行的平均长度。主成分分析表明，两次试验之间的总方差由不同的因素决定。虽然 SF 在第二次试验中家域探索减少，但中心区域占有率增加和低运动是导致 LEO 在重新暴露于 OFT 时观察到的影响的主要因素。总之，我们的新数据支持了斑马鱼在独立 OFT 测试中保持家域的能力，并证实了种群对与探索相关的特定行为参数的影响。
