魔芋葡甘露聚糖对高热能膳食诱导小鼠认知功能障碍及脑部氧化应激状态的影响

Effects of Konjac Glucomannan on Cognitive Dysfunction and Brain Oxidative Stress State in Mice Induced by a High-Calorie Diet

本研究旨在探讨不同分子质量(1、5、90 kDa)魔芋葡甘露聚糖(konjac glucomannan,KGM)对高脂高果糖膳食(high fat and high fructose diet,HFFD)诱导小鼠认知功能障碍及脑部氧化应激状态的干预作用。本实验通过HFFD造模,将90只小鼠随机分为正常饮食组(ND)、阴性对照组(ND+1 kDa KGM、ND+5 kDa KGM、ND+90 kDa KGM)、HFFD模型组(HFFD)、干预组(HFFD+1 kDa KGM、HFFD+5 kDa KGM、HFFD+90 kDa KGM)和阳性对照组(HFFD+KGM)。通过旷场、Y迷宫、水迷宫等行为学实验测试评估小鼠学习记忆能力,脑组织病理学切片观察神经细胞形态变化,测定脑组织谷胱甘肽(glutathione,GSH)相对含量和过氧化氢酶(catalase,CAT)相对活力,分析不同分子质量KGM对HFFD引起的小鼠认知功能紊乱及氧化应激状态的影响。结果显示,不同分子质量KGM均能够显著改善高热能膳食诱导小鼠的工作记忆能力(P<0.05);90 kDa KGM干预组小鼠在旷场及水迷宫定位巡航实验中的总移动距离显著增加(P<0.05);而1 kDa KGM干预组小鼠逃避潜伏期显著缩短(P<0.05),且空间探索实验中小鼠穿越原平台的次数及在平台所在象限的移动距离显著增加(P<0.05)。脑组织病理学切片结果显示,这些分子质量KGM对高热能膳食诱导小鼠海马区神经元的形态异常具有明显改善作用。抗氧化酶活力测定结果表明90 kDa KGM能显著地提高小鼠脑组织中GSH的相对含量(P<0.05),1 kDa KGM能显著增加CAT相对活力(P<0.05)。研究结果表明高分子质量(90 kDa)的KGM可以有效地提高小鼠自发活动能力,而低分子质量(1 kDa)的KGM可以更有效地改善高热能膳食小鼠的学习记忆能力,其机制可能与脑部氧化应激状态有关。

The purpose of this study was to explore the effects of konjac glucomannan(KGM)with different molecular masses(1,5 and 90 kDa)on cognitive dysfunction and brain oxidative stress in mice induced by a high-calorie diet.In this study,90 mice were randomly divided into nine groups:normal diet(ND),negative control(ND+1 kDa KGM,ND+5 kDa KGM,and ND+90 kDa KGM),high-fat and high-fructose diet(HFFD)model,intervention(HFFD+1 kDa KGM,HFFD+5 kDa KGM,and HFFD+90 kDa KGM),and positive control(HFFD+KGM).Behavioral tests including open field,Y maze and Morris water maze tests were conducted to evaluate the learning and memory ability of mice.Meanwhile,the morphological changes of brain nerve cells were evaluated by pathological section,and the relative content of glutathione(GSH)and the relative activity of catalase(CAT)in brain tissue were determined by commercial kits.The results demonstrated that KGM,regardless of its molecular mass,could significantly improve the spatial working memory capacity of mice fed HFFD(P<0.05).The total movement distance of mice in the 90 kDa KGM intervention group was significantly increased in the open field and water maze positioning navigation tests(P<0.05),while supplementation of 1 kDa KGM significantly decreased the escape latency(P<0.05)and significantly increased the number of times that mice crossed the platform location and the movement distance in the quadrant(P<0.05).Immunohistochemical results showed that konjac glucomannan markedly inhibited the morphological abnormalities of hippocampal neurons in the mouse brain induced by HFFD.Similarly,90 kDa KGM significantly increased the relative level of GSH(P<0.05),and 1 kDa KGM significantly up-regulated the relative activity of CAT in mouse brain tissue(P<0.05).These results indicated that konjac glucomannan with high molecular mass(90 kDa)can effectively enhance the spontaneous activity of mice,while konjac glucomannan with low molecular mass(1 kDa)can significantly improve the learning and memory ability of mice fed a high-calorie diet.The underlying mechanism may be related to the oxidative stress state in the brain.