| Summary: | 碩士 === 靜宜大學 === 食品營養學系 === 88 === Abstract
Aging may cause brain neuron atrophy and degeneration、decreasing neurotransmitters and brain function, and finally result in learning and memory ability dysfunction. Because nucleosides and nucleotides are neurotrophic agents, our aim is to study the effects of nucleosides and nucleotides supplementation on learning and memory dysfunction caused by aging. According to the previous studies, nucleosides and nucleotides might affect brain neuron growth and phospholipids synthesis、modulate signal transmission by receptors on the cell membrane, and have a further effect on cell proliferation and neuronal transmission. Although most of the tissues could synthesize nucleotides to meet their requirement, but some organs, such as brain, have to rely on liver; on the other hand, under disease or special physical condition, the requirement of nucleotides are elevated, so that dietary supplementation might be necessary. According to our previous observation, dietary supplementation of 0.5 % nucleosides-nucleotides mixture (NNM) could improve learning and memory ability and decrease the brain degeneration. We proposed to study the effects of different doses of NNM supplementation on learning and memory. Using 7 month-old SAMP8(senescence-accelerated mice prone-8) as subjects, feeding 0.5%、0.3%、0.1% NNM and the control group (non-NNM) diets for 12 weeks. Body weight and food intake were recorded regularly, and the open field test was taken one week prior to the avoidance tests. The single-trial passive avoidance test and the active shuttle avoidance test were conducted at the 8th and 12th week to evaluate the learning and memory. Pathological study of the brain was performed after animal sacrificed. According to the results, body weight and food intake declined at the late phases, but there’s no significant difference between groups. There’s no remarkable difference in the open field test either, but observed decline in the locomotion time after 5 minutes. As for the single-trial passive avoidance test, the difference between groups was not remarkable. But the 0.5 % NNM group showed the best learning and memory ability in the active shuttle avoidance test, and had significantly more avoidance responses than the 0.1% NNM and the control group. The amount of vacuoles and lipofuscin in the cerebral cortex and hippocampus, which have a close relation to memory processes, remarkably declined with the increasing NNM supplementation. The amount of vacuoles in the 0.5 %、0.3 % and 0.1 % group was significantly less than the control group; lipofuscin in the 0.3 % and 0.5 % group also apparently less than the control group, where the 0.5 % group revealed the best improvement. We considered that 0.5 % NNM supplementation could improve the pathological changes in the brain caused by aging, and had an efficient amelioration in learning and memory ability.
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