Department of Child Psychology.
Department of Biobank Center.
Behav Brain Res. 2023 Feb 2;437:114160. doi: 10.1016/j.bbr.2022.114160. Epub 2022 Oct 17.
Anxiety is a common emotional disorder in children. To understand its underlying mechanisms, chronic unpredictable stress (CUS) has been established as a stress model in zebrafish. By using the tall tank test, the stress response reliability could be improved in adult fish which has not been confirmed in larvae. In addition, the increasing evidences have shown that cerebellum plays important roles in anxiety. Whether CUS will affect cerebellar neuronal activity remains unknown. We found that CUS exposure to larvae (from 10 to 17 days post fertilization) induced anxiety-like behaviors and social cohesion impairments within 1-2 d after CUS, including a prolonged freezing time, an increased time spent at the bottom of tank, an increased thigmotaxis index, and an increased interindividual distance. Our results showed that the four behavioral tests were homogeneous, especially the tall tank test either anxiety-like behaviors or the basal locomotion. Furthermore, we found that CUS enhanced the excitability of cerebellar neurons, as the amplitude, frequency, time to peak and half-width of spontaneous firing significantly decreased, as well as the amplitude of excitatory post-synaptic current when compared with the control group. CUS also activated hyperpolarization-activated cyclic nucleotide-gated and potassium channels of cerebellar neurons. Multiple linear regression analysis showed that the total distance in bottom (tall tank test) was correlated positively with outward Na-K currents (r = 0.848, P = 0.016), and the thigmotaxis index (open field test) correlated with action potential amplitude (r = 0.854, P = 0.030). Altogether, early life CUS transiently induced an anxiety-like behavior which could be more accurately assessed by combining the tall tank test with other behavior tests in young zebrafish. CUS increased the excitability of cerebellar neurons might provide new targets to treat emotional diseases such as anxiety.
焦虑是儿童常见的情绪障碍。为了了解其潜在机制，慢性不可预测应激（CUS）已被建立为斑马鱼的应激模型。通过使用高壁水箱测试，可以提高成年鱼的应激反应可靠性，但尚未在幼鱼中得到证实。此外，越来越多的证据表明，小脑在焦虑中发挥重要作用。CUS 是否会影响小脑神经元活动尚不清楚。我们发现，CUS 暴露于幼鱼（从受精后 10 天到 17 天）会在 CUS 后 1-2 天内引起类似焦虑的行为和社会凝聚力受损，包括冻结时间延长、在水箱底部停留时间增加、触壁行为增加和个体间距离增加。我们的结果表明，四项行为测试具有同质性，特别是高壁水箱测试无论是焦虑样行为还是基础运动。此外，我们发现 CUS 增强了小脑神经元的兴奋性，与对照组相比，自发性放电的幅度、频率、到达峰值时间和半宽度以及兴奋性突触后电流的幅度显著降低。CUS 还激活了小脑神经元的超极化激活环核苷酸门控和钾通道。多元线性回归分析表明，底部总距离（高壁水箱测试）与外向钠钾电流呈正相关（r=0.848，P=0.016），触壁指数（旷场测试）与动作电位幅度呈正相关（r=0.854，P=0.030）。总之，早期生活 CUS 短暂诱导出类似焦虑的行为，通过将高壁水箱测试与幼鱼的其他行为测试相结合，可以更准确地评估。CUS 增加小脑神经元的兴奋性可能为治疗焦虑等情绪疾病提供新的靶点。
