Effect And Mechanism Of DHA Supplementation During Development On Rats Spatial Learning And Mecmory Ability

Objective(1) The effects of DHA and another four kinds of oil on the spatial learning and memory ability, lipid peroxidation and serum lipids were studies in rats.(2) Further studies on the dose-effect and time-effect relationship of supplementation of DHA during development of rats improving the spatial learning and memory ability, especially the toxic effect of supplementation of large dose of DHA for long time.(3) To investigate the mechnism of supplementation of DHA during development of rats improving the spatial learning and memory ability.Methods(1) A total of 88 neonatal male SD rats,1 month old, were randomly divided into eleven groups according to the method of random digits table, eight rats in each group. DHA oil, perilla oil, walnut oil, peanut oil and colza oi were divided into two doses of group:2.445ml/kg bw.d and 8.15ml/kg bw.d. Negative control group was independently designed. The sampels were given by way of intragastric administration, keeping for thirty days. After that, the spatial learning and memory ability were detected by Morris water maze test, and the level of total protein, Acetylcholinesterase(AChE), Superoxide dismutase(SOD), Malondialdehyde (MDA), Total cholesterol(TC), High density lipoprotein cholesterol(HDL-C), Triglycerid(TG), Glutamic-oxaloacetic transaminase (GOT) and Glutamic-pyruvic transaminase(GPT) were determined.(2) A total of 144 neonatal male SD rats,1 month old, were randomly divided into six groups according to the method of random digits table: negative control group which fed normal feed, negative control group which fed essential fatty acid-deficient feed, positive control group (Piracetam 400 mg/kg bw.d), low, middle, high dose of DHA group (150, 300,600 mg/kg bw.d), twenty-four rats in each group. After 4 weeks, 8 weeks and 12 weeks of administration respectively, the spatial learning and memory ability were detected by Morris water maze test, and after that the level of total protein, Acetylcholinesterase(AChE), Superoxide dismutase(SOD), Malondialdehyde (MDA) in the brain tissue of rats and blood routine were determined.Results(1) Compared with negative control group, the escape latency decreased significantly (P<0.05, P<0.01) in perilla oil group and walnut oil group, the activity of Acetylcholinesterase(AChE) decreased significantly (P<0.01, P<0.05) in high dose of perilla oil group and walnut oil group, the activity of Superoxide dismutase(SOD) increased significantly in high dose of perilla oil group, peanut oil group and high dose of colza oil group. Compared with negative control group, the activity of Superoxide dismutase(SOD) and malondialdehyde(MDA) content increased significantly in high dose of DHA group, total cholesterol(TC) content decreased significantly in low and high dose of DHA group, the activity of Glutamic-pyruvic transaminase(GPT) increased significantly in low and high dose of peanut oil group.(2) In the Morris water maze test, at 8 weeks of administration, compared with negative control group, the escape latency decreased significantly (P<0.05) in positive control group and middle dose of DHA group, the ratio of the effective time and the number of crossing-platform increased significantly (P<0.05). At 12 weeks of administration compared with negative control group, the escape latency increased significantly (P<0.01) in high dose of DHA group, malondialdehyde(MDA) content of brain increased significantly (P<0.05), the activity of Superoxide dismutase(SOD) decreased significantly (P<0.05), And there was no statistical significance among the other groups about the indexes of AChE, SOD, MDA.Conclusion(1) Supplementation of perilla oil and walnut oil could improve the spatial learning and memory ability, the mechanism might have relationship with acetylcholine system. Perilla oil, peanut oil and colza oil may have anti-oxidant activity. DHA could decrease serum lipids. Supplementation of large dose of DHA may cause elevation of lipid peroxidation and toxic effect.(2) Supplementation of DHA during development of rats improving the spatial learning and memory ability has significant dose-effect and time-effect relationship. Supplementation of large dose of DHA for long time during development of rats could reduce the spatial learning and memory ability(3) The mechanism of DHA improving spatial learning and memory ability might have no significant relationship with AChE, SOD and MDA.