| Objective: To investigate the improved effects of combined nutrients in rats with impaired cognition and motor function and illustrate its possible mechanism.Method: (1) The model with impaired cognition and motor function was established by intrahippocampal injection ofβ-amyloid protein (Aβ). Twenty seven male Sprague-Dawley rats were randomly divided into control group,βamyloid group (Aβ) and saline group. The rats were injected with Aβor saline in bilateral hippocampus (1μl per lateral) in Aβand saline group respectively. Two weeks later, the pathologic changes of hippocampus were observed. The learning and memory ability of rats were examined by water maze test and one trial passive avoidance test. The contents of serum vitamin A and E were determined by fluorospectrophotometry, vitamin C by ultraviolet spectrophotometry, folic acid by chemiluminescence competitive immunoassay, iron, copper and zinc by atomic absorption spectrophotometry and free fatty acids by gas chromatography. The activity of glutathione reductase in blood, aspartic transaminase in erythrocyte and acetylcholine esterase in serum and brain was also determined by ultraviolet spectrometry. (2) Sixteen male Wistar rats were divided into aged group (15months old) and young group (3months old), eight in each. The behavioral tests were carried out through water maze, rod walking and plank walking test. (3) Fourteen male and sixteen female Wistar aged rats were randomly divided into intervened group and control group, seven male and eight female in each. The rats in intervened group were fed with diets supplemented with combined nutrients and mixed plant extract administered intragastrically at 4ml/kg bw/d, while the rats in control group were fed with basic diets and water. The experiment lasted 10 weeks. The cognition and motor behavior was tested with water maze and rod walking test. The levels of noradrenaline, serotonin, dopamine in brain and vitamin E in serum were determined by fluorospectrophotometry, brain acetylcholine, serum protein and albumin, activities of brain and serum acetylcholine esterase, blood glutathione peroxidase, serum total anti-oxidation capability and hydroxy radical inhibition capability by ultraviolet spectrophotometry. The changes of long-term potentiation in hippocampal dentate gyrus were observed through electrophysiology, and protein synthesis in frontal cortex by two dimensional gel electrophoresis. The expressed differential proteins were identified by analysis of peptide mass fingerprint and database retrieval. Western blotting was used to identify the changes of stathmin 1 expression. Results: (1) Deposition of Aβand pathological changes were not observed in hippocampus in Aβgroup. Compared with control group, the learning and memory in Aβgroup decreased but it's insignificant. The contents of serum vitamin C and iron decreased in Aβgroup, while the activity of acetylcholine esterase in brain and serum increased significantly.The composition of free fatty acids in serum changed significantly. (2)Compared with young rats, the cognition and motor function of aged rats declined, but restored after intervention by combined nutrients. (3) In intervened group, the anti-oxidation capability and vitamin E contents in serum, the contents of acetylcholine, noradrenaline, serotonin and dopamine in brain were increased, but acetylcholine esterase activity in serum and brain decreased. The amplitude of long-term potentiation in hippocampal dentate gyrus and the efficacy of hippocampal synaptic transmission were significantly elevated. Eleven protein spots with changes of contents were observed in two dimensional gel electrophoresis maps and ten of them were identified successfully. Among the identified proteins, six proteins decreased in frontal cortex of dietary supplemented rats including pyruvate kinase, pyruvate dehydrogenase E1 alpha 1, aspartate transaminase, mitochondrial creatine kinase 1, voltage-dependent anion channel 2 protein and triosephosphate isomerase 1, while the other four proteins increased, including peroxiredoxin 2, subunitd of mitochondrial H-ATP synthase, stathmin 1 and Cu-Zn superoxide dismutase. The results of Western blotting confirmed that frontal cortex stathmin 1 in intervened group increased than that in control group. Conclusion: The aged rat can be taken as model with impaired cognition and motor function to study the effects of nutrition intervention and the mechanisms involved. The combined nutrients have improved effects on cognition and motor function of aged rats and the effects might correlate with improved anti-oxidation status, elevated neurotransmitter level, increased efficacy of synaptic transmission and increased expression of protein related to cognition in frontal cortex. Stathmin 1 might protect the neuron in aged rat.
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