PDF(Pubmed)
Abstract：
Prolonged hyperglycemia causes long-term vision complications and an increased risk of cognitive deficits. High blood sugar also confers an osmotic load/stress to cells. We assessed behavioral and neurochemical changes in zebrafish brain and retina following prolonged hyperglycemia for 4-weeks or 8-weeks. At each time point, behavior was assessed using 3-chamber choice task and optomotor response; tissue was then collected and levels of inflammatory markers, tight junction proteins, and neurotransmitters determined using Western Blots. After 4-weeks, brain levels of v-rel reticuloendotheliosis viral oncogene homolog A (avian) (RelA; NF-kB subunit), IkB kinase (IKK), and glial fibrillary acidic protein (GFAP) were significantly elevated; differences in zonula occludens-1 (ZO-1), claudin-5, glutamic acid decarboxylase (GAD), and tyrosine hydroxylase (TH) were not significant. In retina, significant differences were observed only for TH (decreased), Rel A (increased), and GFAP (increased) levels. Glucose-specific differences in initial choice latency and discrimination ratios were also observed. After 8-weeks, RelA, GAD, and TH were significantly elevated in both tissues; IKK and GFAP levels were also elevated, though not significantly. ZO-1 and claudin-5 levels osmotically decreased in retina but displayed an increasing trend in glucose-treated brains. Differences in discrimination ratio were driven by osmotic load. OMRs increased in glucose-treated fish at both ages. In vivo analysis of retinal vasculature suggested thicker vessels after 4-weeks, but thinner vessels at 8-weeks. In vitro, glucose treatment reduced formation of nodes and meshes in 3B-11 endothelial cells, suggesting a reduced ability to form a vascular network. Overall, hyperglycemia triggered a strong inflammatory response causing initial trending changes in tight junction and neuronal markers. Most differences after 4-weeks of exposure were observed in glucose-treated fish suggesting effects on glucose metabolism independent of osmotic load. After 8-weeks, the inflammatory response remained and glucose-specific effects on neurotransmitter markers were observed. Osmotic differences impacted cognitive behavior and retinal protein levels; protein levels in brain displayed glucose-driven changes. Thus, we not only observed differential sensitivities of retina and brain to glucose-insult, but also different cellular responses, suggesting hyperglycemia causes complex effects at the cellular level and/or that zebrafish are able to compensate for the continued high blood glucose levels.
摘要：
长时间的高血糖会导致长期的视力并发症和认知障碍的风险增加。高血糖还赋予细胞渗透负荷/压力。我们评估了持续4周或8周高血糖后斑马鱼大脑和视网膜的行为和神经化学变化。在每个时间点,行为评估使用三室选择任务和视电机反应;然后收集组织和炎症标记物的水平，紧密连接蛋白，和使用西方印迹确定的神经递质。4周后,v-rel网状内皮增生病病毒癌基因同源物A（禽）（RelA；NF-kB亚基）的脑水平，IkB激酶(IKK),和胶质纤维酸性蛋白（GFAP）显着升高；小带闭塞-1（ZO-1）的差异，claudin-5，谷氨酸脱羧酶（GAD），酪氨酸羟化酶(TH)无显著差异。在视网膜中,仅在TH（下降）中观察到显着差异，RelA(增加),和GFAP（增加）水平。还观察到初始选择潜伏期和辨别比的葡萄糖特异性差异。8周后,Rela,GAD,和TH在两个组织中都显着升高；IKK和GFAP水平也升高，虽然不是很重要。ZO-1和claudin-5水平在视网膜中渗透降低，但在葡萄糖处理的大脑中显示出增加的趋势。区分率的差异是由渗透负荷驱动的。在两个年龄段，经过葡萄糖处理的鱼的OMR均增加。视网膜血管系统的体内分析提示4周后血管较厚，但在8周时血管更薄。体外，葡萄糖治疗减少了3B-11内皮细胞中节点和网状物的形成，表明形成血管网的能力降低。总的来说,高血糖引发强烈的炎症反应,导致紧密连接和神经元标志物的初始趋势变化.暴露4周后，在葡萄糖处理的鱼中观察到大多数差异，表明对葡萄糖代谢的影响与渗透负荷无关。8周后,炎症反应仍然存在,并观察到葡萄糖对神经递质标志物的特异性影响.渗透差异影响认知行为和视网膜蛋白质水平；大脑中的蛋白质水平显示出葡萄糖驱动的变化。因此，我们不仅观察到视网膜和大脑对葡萄糖损伤的不同敏感性，但也有不同的细胞反应，提示高血糖在细胞水平引起复杂的影响和/或斑马鱼能够补偿持续的高血糖水平。
