Yamagami Hikaru, Fuji Tatsuya, Wako Mayumi, Hasegawa Yasushi
College of Environmental Technology, Muroran Institute of Technology, 27-1 Mizumoto, Muroran 050-8585, Japan.
Antioxidants (Basel). 2021 Mar 24;10(4):505. doi: 10.3390/antiox10040505.
Pearl and nacre have been used in traditional medicines for treating brain dysfunctions, such as epilepsy, myopia, palpitations and convulsions. We previously showed that a pearl oyster nacre extract improves scopolamine-induced memory impairments using the Y-maze, Banes maze and object recognition tests. In this study, we aimed to isolate the memory-improving substance using ion-exchange column chromatography and reverse-phase column chromatography and elucidate the molecular mechanism underlying its memory-improving activity. The isolated substance was found to be a sulfated polysaccharide with a molecular weight of approximately 750 kDa. Monosaccharide composition analysis showed that it was rich in galactose, glucose, mannose and uronic acid. Furthermore, the mRNA expression levels of oxidative stress, inflammatory response and neuroprotective factors in the cerebral cortex were investigated. Treatment with the polysaccharide increased the expression levels of the antioxidant enzymes Cu, Zn -superoxide dismutase (SOD) and catalase and attenuated the scopolamine-mediated upregulation of the inflammatory cytokines interleukin-1 and interleukin-6. In addition, the polysaccharide suppressed the decrease in the expression levels of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF). These findings strongly suggest that the polysaccharide in the nacre extract mediated its antiamnesic effects by preventing oxidative stress and inflammation and increasing the expression levels of BDNF and NGF.
珍珠和珍珠母已被用于传统医学中治疗大脑功能障碍，如癫痫、近视、心悸和抽搐。我们之前的研究表明，珍珠贝珍珠母提取物通过Y迷宫、巴恩斯迷宫和物体识别测试改善了东莨菪碱诱导的记忆损伤。在本研究中，我们旨在利用离子交换柱色谱法和反相柱色谱法分离出具有改善记忆作用的物质，并阐明其改善记忆活性的分子机制。结果发现，分离出的物质是一种分子量约为750 kDa的硫酸化多糖。单糖组成分析表明，它富含半乳糖、葡萄糖、甘露糖和糖醛酸。此外，还研究了大脑皮层中氧化应激、炎症反应和神经保护因子的mRNA表达水平。多糖处理增加了抗氧化酶铜、锌超氧化物歧化酶（SOD）和过氧化氢酶的表达水平，并减弱了东莨菪碱介导的炎症细胞因子白细胞介素-1和白细胞介素-6的上调。此外，多糖抑制了脑源性神经营养因子（BDNF）和神经生长因子（NGF）表达水平的下降。这些发现有力地表明，珍珠母提取物中的多糖通过预防氧化应激和炎症以及增加BDNF和NGF的表达水平来介导其抗遗忘作用。
