The Improving Effects Of LSAE On The Learning And Memory’s Impairment Mice Induced By D-galactose

Objective:To investigate the effects of Litchi Seed Extract (Litchi Seed Aqueous Extracts,LSAE) on learning and memory disordered in murine induced by D-galactose, andstudy the possible mechanism of action.Method:2month-old50Kunming mice,20±2g, sharing equal numbers in genders,randomly divided into normal control group (Normal,10mice) and model group (40mice). Mice in the model group were injected with D-galactose (500mg kg-1d-1)continuously subcutaneously for8weeks in order to establish learning and memorydeficits model while normal counterparts were subcutaneously injected with saline.From the5th week, the40mice were further randomized into the following subgroupsand fed with drugs respectively for4weeks i.e. model group (Model,10mice),huperzine A group (huperzine, A, HU,10mice,0.4mg kg-1d-1), litchi extract highdose group (LSAE H,10mice,60g kg-1d-1) and litchi low dose group (LSAE L,10mice,15g kg-1d-1), normal control group and model control group were administratedwith distilled water (10ml kg-1d-1). From the8th week, spontaneous activity of micewas tested by SMART video-tracking system while the learning and memory abilitieswere evaluated by Morris water maze. Use chemical colorimetry to measuresuperoxide dismutase (SOD) activity, and glutathione peroxidase (GSH-Px) activity,malondialdehyde(MDA), advanced glycation end products (AGEs) content in serum,and measure nitric oxide (NO) content, nitric oxide synthase(NOS) activity, asacetylcholine(Ach) content, acetylcholinesterase(AchE) activity in the brain tissue.Flow cytometry (flow cytometer, FCM) was adopted to determin the potential ofbrain cells mitochondrial membrane. AGEs and Aβ of hippocampal tissues weredetected by immunohistochemistry. RT-PCR method was used to measurebcl-2mRNA, baxmRNA and β-amyloid precursor protein (β-APP) mRNA expression in hippocampus. Transmission electron microscopy was used to observe the changesof mitochondria structure.Result:(1) Compared with the normal group, the spontaneous activities in the modlegroup were decreased significantly, with slower average speed (p<0.05, p<0.01)during day and night, and increased resting time rates (p<0.01, p<0.01) during dayand night, shorten fast motion time rates (p<0.01, p<0.01) during day and night, andincreased slow motion time rate (p<0.05) during day time. Learning and memoryability decreased significantly, showed as the escape latency was significantlyprolonged (p<0.01), time rate in target zone was significantly shorten (p<0.01) andthe number of passing through the platform was decreased significantly (p<0.01) inthe Morris water maze.(2) In comparison with the normal group, model group’s serum SOD andGSH-Px activity decreased obviously (P<0.01, P<0.01), the level of MDA increasedsignificantly (P<0.01), and the content of AGEs increased significantly (p<0.05), inthe brain tissue the content of NO was significantly increased (p<0.05), so as the NOSactivity (p<0.05). The Ach content decreased obviously (p<0.05), while the activity ofAchE increased significanty (p<0.05), mitochondrial membrane potential decreasedsignificantly (p<0.05). The expression of bcl-2mRNA decreased (p<0.01), whilebaxmRNA was significantly increased (p<0.01) and β-APPmRNA (p<0.05),hippocampus’s AGEs and Aβ increased significantly, mitochondria in hippocampalneurons were reduced in number, swelled in shape, mitochondrial cristae vague,shortened or even disappeared, matrix reduced, membrane ruptured, vacuolardegenerated.(3) For the LSAE(high dose and low dose), the rest time rates were reduced(p<0.01, p<0.01), the fast movement time rates increased (p<0.01, p<0.01) during theday time compared with the model group; for the LSAE (low dose) the average velocity was increased (p<0.05), the fast movement time rate was increased (P <0.05)during the night time. The escape latency were shortened (p<0.05, p<0.01) for theLSAE (high dose and low dose) in Morris water maze.(4) For the LSAE (high dose and low dose), serum SOD activity were increased(p<0.01, p<0.01) as the GSH-Px activity increased (p<0.01, p<0.01) compared withthe model group, while the content of MDA (p<0.05) was decreased of LSAE(lowdose), and the AGEs content of serum was decreased (p<0.05) of LSAE (high dose)..(5) Compared with the model group mice, the levels of NO in brain tissue weredecreased (p<0.05, p<0.05) of LSAE (high dose and low dose), as the activity of NOSwere decreased (p<0.05, p<0.05).(6) Differing from the model group, the mitochondrial membrane potential inbrain cells was improved of LSAE (high dose)(p<0.05).(7) The expressions of bcl-2mRNA in brain were increased (p<0.05, p<0.05) inLSAE (high dose and low dose), while the expressions of baxmRNA were decreased(p<0.01, p<0.05), as β-APPmRNA was decreased (p<0.05) in the LSAE (low dose)with contrast to the model group mice.(8) Compared with the model group, hippocampus AGEs, Aβ were reduced, andthe mitochondrial ultrastructure in hippocampus were protected for LSAE (high doseand low dose).Conclusion:In Morris water maze, LSAE can improve the learning and memory impairmentsin the mice induced by D-galactose, which may be related to increasing the anti-oxidative ability.