Georgia Southern University, Armstrong Campus, Savannah, GA 11935, USA.
Cells. 2021 Mar 12;10(3):637. doi: 10.3390/cells10030637.
Evidence from human and animal studies indicate that disrupted light cycles leads to alterations of the sleep state, poor cognition, and the risk of developing neuroinflammatory and generalized health disorders. Zebrafish exhibit a diurnal circadian rhythm and are an increasingly popular model in studies of neurophysiology and neuropathophysiology. Here, we investigate the effect of alterations in light cycle on the adult zebrafish brain: we measured the effect of altered, unpredictable light exposure in adult zebrafish telencephalon, homologous to mammalian hippocampus, and the optic tectum, a significant visual processing center with extensive telencephalon connections. The expression of heat shock protein-70 (HSP70), an important cell stress mediator, was significantly decreased in optic tectum of adult zebrafish brain following four days of altered light exposure. Further, pSer473-Akt (protein kinase B) was significantly reduced in telencephalon following light cycle alteration, and pSer9-GSK3β (glycogen synthase kinase-3β) was significantly reduced in both the telencephalon and optic tectum of light-altered fish. Animals exposed to five minutes of environmental enrichment showed significant increase in pSer473Akt, which was significantly attenuated by four days of altered light exposure. These data show for the first time that unpredictable light exposure alters HSP70 expression and dysregulates Akt-GSK3β signaling in the adult zebrafish brain.
来自人类和动物研究的证据表明，光周期的紊乱会导致睡眠状态的改变、认知能力下降，以及神经炎症和全身性健康紊乱的风险增加。斑马鱼表现出昼夜节律，并且在神经生理学和神经病理生理学研究中成为越来越受欢迎的模型。在这里，我们研究了光周期变化对成年斑马鱼大脑的影响：我们测量了改变成年斑马鱼端脑（与哺乳动物海马体同源）和视顶盖（具有广泛端脑连接的重要视觉处理中心）中光暴露的不可预测性对其的影响。在经过四天的光暴露后，成年斑马鱼大脑视顶盖中的热休克蛋白 70（HSP70）的表达显著降低，HSP70 是一种重要的细胞应激介质。进一步的研究表明，光周期改变后，端脑中的 pSer473-Akt（蛋白激酶 B）显著减少，而光改变后的鱼的端脑和视顶盖中的 pSer9-GSK3β（糖原合成酶激酶 3β）也显著减少。暴露于五分钟环境富集的动物表现出 pSer473Akt 的显著增加，而四天的光暴露则显著减弱了这一增加。这些数据首次表明，不可预测的光暴露会改变成年斑马鱼大脑中的 HSP70 表达，并使 Akt-GSK3β 信号通路失调。
