Yang Di, So Kwok-Fai, Lo Amy Cy
Department of Ophthalmology, First Affiliated Hospital of Kunming Medical University, Kunming Medical University, Kunming, Yunnan, China.
Department of Ophthalmology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong.
Clin Exp Ophthalmol. 2017 Sep;45(7):717-729. doi: 10.1111/ceo.12950. Epub 2017 Apr 27.
Retinal ischaemia is a common feature shared by numerous eye diseases. Ischaemic insult leads to retinal dysfunction and neuronal death. Lycium barbarum polysaccharides are well known for eyesight preservation. We have previously reported the effect of Lycium barbarum polysaccharides on cell death, blood ocular barrier and oxidative stress within 24 h retinal ischaemia. This study focuses on retinal function and looks for ultrastructural and cellular correlates after a relatively long period of reperfusion for 7 days.
Two-hour ischaemia was induced by intraluminal occlusion of the internal carotid artery. Either Lycium barbarum polysaccharides or phosphate-buffered saline was orally pre-administered daily for 7 days before ischaemia and continued for 1, 3 and 7 days after reperfusion. Electroretinogram was performed to evaluate visual function. Paraffin-embedded retinal sections were prepared 7 days after reperfusion and utilized for histological and immunohistochemical analyses.
Ischaemia led to sustained inhibition of b-wave amplitude and oscillatory potentials. Lycium barbarum polysaccharide-treated mice exhibited greater b-wave and oscillatory potential responses from days 1 to 7 after reperfusion. In addition, increased number of viable cells and calretinin-positive cells, as well as enhanced immunoreactivity of protein kinase C alpha and attenuated glial fibrillary acidic protein expression, was noted in Lycium barbarum polysaccharide-treated retina.
Daily consumption of Lycium barbarum polysaccharides effectively alleviated ischaemia-induced retinal dysfunction as well as reduced correlated neuronal death and glial activation. This prolonged effect could last at least 7 days. It suggested that Lycium barbarum polysaccharides might serve as a neuroprotective agent in ischaemic retinopathies.
视网膜缺血是多种眼部疾病共有的常见特征。缺血性损伤会导致视网膜功能障碍和神经元死亡。枸杞多糖以保护视力而闻名。我们之前报道了枸杞多糖对视网膜缺血24小时内细胞死亡、血眼屏障和氧化应激的影响。本研究聚焦于视网膜功能，并在相对较长的7天再灌注期后寻找超微结构和细胞层面的关联。
通过颈内动脉腔内闭塞诱导两小时的缺血。在缺血前7天每天口服给予枸杞多糖或磷酸盐缓冲盐水，并在再灌注后持续1、3和7天。进行视网膜电图以评估视觉功能。在再灌注7天后制备石蜡包埋的视网膜切片，并用于组织学和免疫组织化学分析。
缺血导致b波振幅和振荡电位持续受到抑制。枸杞多糖处理的小鼠在再灌注后第1天至第7天表现出更大的b波和振荡电位反应。此外，在枸杞多糖处理的视网膜中，可见存活细胞和钙视网膜蛋白阳性细胞数量增加，蛋白激酶Cα的免疫反应性增强，胶质纤维酸性蛋白表达减弱。
每日摄入枸杞多糖可有效减轻缺血诱导的视网膜功能障碍，并减少相关的神经元死亡和胶质细胞激活。这种延长的效应至少可持续7天。这表明枸杞多糖可能作为缺血性视网膜病变的神经保护剂。
