Effects Of N-acetylneuraminic Acid On 2-vessels Occlusion Induced Vascular Dementia Rats

Objective:Toinvestigatetheeffectsandmechanismsof N-acetylneuraminic acid?Neu5Ac?on vascular dementia?VaD?rats induced2-vessels occlusion?2-VO?method.Methods:Male rats(Sprague dawley,SD of Specefic Pathogen Free?SPF?grade were used?weighing 180 g²20 g?.The rats were housed in a standard laboratory with 12 h light-dark cycles and free access to food and water.After 7 days of acclimation,except ten rats in control group were treated with sham operation only,the other rats were treated with2-VO to establish the VaD models.Three days after the operation,forty surviving VaD rats were randomly divided into five groups with 8 rats per group,as model,nimotop and three Neu5Ac groups.Rats in control and model group were oral treated with pure water,rats in nimotop group were oral treated with nimotop(11 mg·kg^-1,dissolved in 0.5%CMC-Na),rats in Neu5Ac groups were oral treated with Neu5Ac(32,63,126 mg·kg^-1,dissolved in pure water),all the rats were treated by 10 mL·kg^-11 and once a day last for thirty consecutive days.One hour after the last treatment,the place navigation tests were run,a platform with a diameter of 10 cm was placed 1.5 cm below the water surface,the escape latencies?s?of each rat in four quadrants were recorded in ninty seconds and the mean escape latencies of each rat were calculated.After the place navigation test,and the platform was removed,the spatial probe tests were run immediately for ninty seconds,the indexes as time in target quadrant?s?and target crossing?n?were recorded.After the spatial probe tests,all the rats were fasted,but allowed water,for 14¹6 h,the blood samples were collected,the rats were sacrificed and organs as brains,hearts,lungs,livers,spleens,kidneys,thymus glands,testis and epididymis were removed and weighed,the organ indexes were calculated.The routine examination of blood indexes as White Blood Cell?WBC?,Red Blood Cell?RBC?,Hemoglobin?HGB?,Hematocrit?HCT?,Platelet?PLT?,Reticulocytes?Ret?,Neutrophilicgranulocyte?NEUT?,Lymphocyte?LYMPH?,Monocytes?MONO?,Eosimophil?EO?and Basophile?BASO?were examined by automatic blood cell analyzer.The fasting serum biochemical indicators as Albumin?ALB?,Alkaline Phosphatase?ALP?,Alanine amiotransferase?ALT?,Aspartate aminotransferase?AST?,Blood Urea Nitrogen?BUN?,Creatinine?CREA?,Lactate Dehydrogenase?LDH?,Total Bilirubin?TBIL?,Total Protein?TP?,Total Cholesterol?TCHO?,Triglyceride?TG?,High density lipoprotein cholesterol?HDLC?,Low density lipoprotein cholesterol?LDLC?were determined by automatic biochemical analyzer.The inflammatory factors as Interleukin-1??IL-1??,IL-6,ransforming growth factor-??TGF-??and Tumor necrosis factor-??TNF-??were examined by enzyme marker using the enzyme-linked immunosorbent assay?ELISA?method.The oxidative stress indexes in brain as Superoxide dismutase?SOD?,Malonyldialdehyde?MDA?,Reduced glutathioe?GSH?and Glutathione peroxidase?GSH-Px?were examined by enzyme marker or Spectrophotometer according to methods of the test kit.Results:The observation on the last day of treatment showed that after2-VO operation and treated for thirty days,the main clinical signs of the VaD rats were spiritual lessness,quiet,lie prostrate,large abdomen,fat and slow reaction.The clinical signs in Neu5Ac groups were obviously alleviated.Compared with model group,the bodyweight in Neu5Ac groups were obviously decreased,and the weight gain were significantly decreased?P<0.05 or P<0.01?,but the mean bodyweight and weight gain were still bigger than the rats in control group.Compared with model group,the escape latencies of the Neu5Ac groups rats in four quadrants were not significantly changed?P>0.05?,but the mean escape latencies in Neu5Ac 63,126 mg·kg^-11 groups were significantly decreased?P<0.01?,the time in target quadrant were significantly increased?P<0.01?in all the Neu5Ac groups,and the numbers of target crossing were significantly increased?P<0.05 or P<0.01?in Neu5Ac 63,126 mg·kg^-11 groups.Compared with model group,the routine examination of blood indexes not significantly changed?P>0.05?.Compared with model group,the fasting serum biochemical indicators as TBIL,TG were significantly decreased?P<0.01?in all the Neu5Ac groups,ALT and AST were were significantly decreased?P<0.05 or P<0.01?in Neu5Ac 63,126 mg·kg^-11 groups,and BUN were significantly decreased?P<0.01?in Neu5Ac 126 mg·kg^-11 groups,the other indicators not significantly changed?P>0.05?.Compared with model group,the levels of inflammatory factors as IL-6,TNF-?and IL-1?were significantly decreased?P<0.05 or P<0.01?in all the Neu5Ac groups,but the levels of TGF-?not significantly changed?P>0.05?.Compared with model group,the levels of oxidative stress indexes in brain as SOD and GSH were significantly increased?P<0.05 or P<0.01?in all the Neu5Ac groups,the levels of GSH-Px were significantly increased?P<0.05 or P<0.01?in Neu5Ac 63,126 mg·kg^-11 groups,and the levels of MDA were significantly decreased?P<0.05 or P<0.01?in Neu5Ac 63,126 mg·kg^-11 groups.Compared with model group,the heart indexes were significantly increased?P<0.05?in Neu5Ac 63 mg·kg^-11 group,the weight and indexes the other organs not significantly changed?P>0.05?.In all the Neu5Ac groups,the histopathological changes of the brains'cone cells and the hippocampuses neurons were obviously alleviated,the numbers of normal neurons were obviously increased,and the numbers of deadly neurons were obviously decreased.Conclusions:Neu5Ac has low toxicity according to our study,no obviously toxicity was found to VaD rats after thirty days treatment,has good therapeutic effects in healing VaD rats induced 2-VO,it may be related to enhance the body-antioxidant capacity,decreasing the pro-inflammatory cytokine levels,improving the liver functions and renal functions,protecting the neurons and alleviating the histopathological changes of the brains and hippocampuses.