Effects Of Radix Polygalae On Learning And Memory, Hippocampal Long-Term Potentiation And SOD, MDA Level Of Brain Tissue In Aging Rats

Aging has become a more and more hot issue in modern society with the acceleration of population senescence in the world. Studies have confirmed that aging is closely related to the occurrence of neurodegenerative diseases such as Alzheimer's disease and so on. So the investigation of finding effective drugs that can delay the aging process and exploring the mechanism may provide beneficial assistant to prevention and treatment of degenerative diseases.Hippocampal long-term potentiation (LTP), a persistent enhancement of excitatory synaptic transmission induced by high-frequency stimulation (HFS), is a form of plasticity of synaptic transmission. It has been accepted as a popular electrophysiological model for learning and memory.There are many theories of aging mechanism in the modern medicine research, the destructive effects of free radicals in which is agreed by majority of scholars. Malondialdehyde (MDA) is a lipid peroxidation. It can cause lipid peroxidation by attacking the polyunsaturated fatty acids in biofilm. But superoxide dismutase (SOD) plays a vital role in balance between oxidation and anti-oxidation. It can protect cells from damaging by removing the superoxide anion radical (O2-.).Therefore, MDA and SOD can be used as an indicator that reflecting the information of aging body.According to the Chinese Materia Medica, Radix Polygalae is guessed to have a special effect upon the will and the mental powers, improving understanding and strengthening the memory. It has been recognized as a miracle drug that can enhance intelligence or wisdom for thousands years. But investigation of its mechanism of anti-aging is still in an exploratory stage especially the influence to LTP in hippocampus. In this thesis, we use electrophysiological method to induce in vivo LTP in the hippocampus CA1 region as the model of synaptic plasticity, and Morris maze test was used to evaluate the learning and memory of each rat, SOD and MDA in the brain tissue were measured in order to observe the anti-ageing effect of Radix Polygalae. Objective: To observe the effects of Radix Polygalae on learning and memory of model rats caused by D-gal, and to prove whether the effects were dose-dependent.Methods:32 male Wistar rats were divided randomly into four groups, i.e. control group, model group, high dose Radix Polygalae group and low dose Radix Polygalae group. Morris maze test was used to evaluate the learning and memory of each rat.Results:(1) Through five days of trainging, each rat appeared learning and memory ability with the escape latency shortened gradually; (2) Compared with control group, the time of staying at platform quad was significantly shortened (P<0.01) and the time of passing platform was significantly decreased (P<0.01) in model group; Compared with model group, the time of staying at platform quad were significantly prolonged(P<0.01, P<0.05), and the times of passing platform were significantly increased(P<0.01, P<0.05) in both high dose group and low dose group; Furthermore, the time of staying at platform quad was significantly prolonged (P<0.05) and the time of passing platform was significantly increased (P<0.05) in high dose group than low dose group.Conclusion:Radix Polygalae can improve learning and memory ability of aging rats dose-dependently.Partâ…¡Effects of Radix Polygalae on Long-Term Potentiation in Hippocampus in Vivo of Aging Rats Caused by D-galObjective: To observe the effects of Radix Polygalae on long-term potentiation in hippocampus in vivo of model rats caused by D-gal and to investigate the mechanism underlying the effects of Radix Polygalae on learning and memory; and to prove whether the effects were dose-dependent.Methods:The groups were assigned as Partâ… . In vivo LTP in the hippocampus CA1 region was represented by the ratio of fEPSP amplitudes before and after high frequency stimulation (HFS) after Morris maze test.Results:Compared with control group, the LTP was significantly restrained (P<0.01) in model group; Compared with model group, the LTPs were significantly enhanced(P<0.01, P<0.01) in both high dose group and low dose group. Furthermore, the LTP was significantly enhanced in high dose group than low dose group (P<0.05). Conclusion:Radix Polygalae can improve the learning and memory ability of aging rats by reducing the restraint to LTP caused by D-gal, and improving the synaptic plasticity dose-dependently.Partâ…¢Effects of Radix Polygalae on SOD, MDA in Brain Tissue in Aging Rats Caused by D-galObjective:To observe the effects of Radix Polygalae on SOD and MDA in brain tissue caused by D-gal and to investigate the mechanism underlying the effects of Radix Polygalae on learning and memory; and to prove whether the effects were dose-dependent.Methods:The groups were assigned as Partâ… . After the former test, brain tissues of each rat were separated from cranial cavity, then detect the activity of SOD by xanthine oxidase method and examine the level of MDA though TBA colorimetric.Results: Compared with control group, the activity of SOD was significantly reduced (P<0.01) and the level of MDA was significantly increased (P<0.01) in model group; Compared with model group, the activity of SOD were significantly elevated (P<0.01, P<0.01) and the level of MDA were significantly lessened (P<0.01, P<0.01) in both high dose group and low dose group. Furthermore, the activity of SOD was more elevated (P<0.05), and the level of MDA was more lessened (P<0.05) in high dose group than low dose group.Conclusion: Radix Polygalae can improve the learning and memory ability of aging rats by improving the antioxidative enzyme ability, eliminating the free radical, lessening the lipid peroxidation effect dose-dependently.