高饱和脂肪饮食对老年大鼠学习记忆和脑Aβ生成的影响及机制

Effect of high-saturated-fat diet on learning and memory and Aβ generation of aged rat brain and its mechanism

目的观察高饱和脂肪饮食对老年大鼠学习记忆和脑β-淀粉样蛋白(Aβ)生成的影响及机制。方法 26只雄性老年大鼠随机分为对照组和高饱和脂肪组各13只,对照组大鼠给予正常饲料,高饱和脂肪组大鼠给予含15%牛油饲料,喂养3个月。用Morris水迷宫测定大鼠学习记忆能力,用酶联免疫吸附法(ELISA)测定海马Aβ含量,用免疫组织化学染色检测脑内β-淀粉样前体蛋白(APP)表达,用黄嘌呤氧化酶法测定血清及脑组织总超氧化物歧化酶(SOD)活性。结果与对照组相比,高饱和脂肪组大鼠平均逃避潜伏期明显延长(P<0.05),穿越原平台所在位置次数显著减少(P<0.01),脑皮质和海马区APP蛋白表达明显增多(P<0.01,P<0.05),海马Aβ含量显著升高(P<0.01),血清及脑组织总SOD水平均显著降低(P<0.01,P<0.05)。结论高饱和脂肪饮食降低学习记忆能力、增加APP和Aβ水平,其机制可能与降低脑抗氧化能力有关。

Objective To explore the effects of high-saturated-fat diet on learning and memory and Aβ generation of rat brain and investigate its mechanism.Methods Twenty six males aged rats were randomly divided into control and high-saturated-fat groups（ n = 13each）. The control group was given a normal diet,and the high-saturated-fat group was given high-saturated-fat diet containing 15% beef tallow for three months. The spatial learning and memory abilities were examined by Morris water maze test. Aβ40 content in hippocampal was measured by ELISA. β-amyloid-precursor protein（ APP） expression was measured by immunohistochemistry staining. Serum and brain total superoxide dismutase（ SOD） activities were measured by detecting xanthine oxidase activity.Results Compared with the control group,the average escape latency prolonged and platform crossing number were decreased in the high-fat group. Cerebral cortex and hippocampus APP protein expression and hippocampal Aβ40 content were increased significantly in the high-fat group. Total SOD activities in serum and brain tissue in the high-fat group were significantly lower than those of control group.Conclusions High-saturated-fat diet might reduce the ability of learning and memory and promote Aβ generation,and its mechanism might be related to decreasing antioxidant capacity of brain.