Effects Of Medium Chain Triglycerides And α-linolenic Acid On The Norepinephrine,Dopamine Metabolism And Brain Function In The APP/PS1 Transgenic Mice

Objective1.To investigate the effects of a-linolenic acid and medium-chain fatty acid on the learning and memory function in the APP/PS1 transgenic mice,and to explore the related mechanisms.2,To observe the effects of a-linolenic acid and medium-chain fatty acid on the DA and NE in the APP/PS1 transgenic mice,and to explore the related mechanisms.3.To investigate the effects of a-linolenic acid and medium-chain fatty acid on the weight,serum lipid and β-hydroxybutyric acid levels in the APP/PS1 transgenic mice.Methods1.25 APP/PS1 transgenic mice(APPSWe.PSENld9)aged 4 weeks old,were randomly divided into ALA+MCFA(combined intervention group),MCFA group(Intervention group)and LCFA group(control group)according to their fasting weight,and 10 wild type mice(WT,No APP or PS1 genotype)were considered as normal group.2.The mice were fed different fatty acid formula for 36 weeks.The Morris water maze was used to analyze the differences of behavioral experiment in each group.Positioning navigation test training was conducted in the first four days,the space exploration experiment was finished in the fifth day.3.There was a statistical difference of behavioral experiment among the groups of mice,then to execute each mouse and isolate their hippocampus and cortical tissue.The APP,Aβ42,Tau,TH and MAO protein levels were detected with Western blot,and the immunohistochemical method was used to detect Aβ deposition in the brain.4.After taking blood,the serum lipid levels in each group were measured by enzyme analysis.The effects of various fatty acids on the norepinephrine,dopamine metabolism and β-hydroxybutyric acid in the APP/PS1 transgenic mice were compared with the technique of high performance liquid chromatography-tandem mass spectrometry(HPLC-MS-MS).Results1.Morris water maze test:In the navigation experiment,compared with the LCFA group,the average escape latency in the ALA+MCFA group was significantly shorter on the 2nd,3rd,and 4th days(p<0.05),and on the 4th day it was significantly shorter than the MCFA group(p<0.05).The mean latency of MCFA group is relatively stable,and there is a significant statistical difference(p<0.05)compared with LCFA group on the first and fourth days(p<0.05).Intra-comparisons showed that the mean escape latency only in the ALA+MCFA group was significantly decreased on the 3rd and 4th days,respectively(p<0.05).It also indicated that the learning ability of the mice in this group was most improved.In the pace exploration experiment,the average times of four groups of mice across the platform in the quadrant where the platform was setted(quadrant III),respectively are:2.63 times in ALA + MCFA group,2.44 times in MCFA group,0.25 times in LCFA group,and 2.78 times in WT group.The results of variance analysis showed that the difference of ALA+MCFA or MCFA was statistically significant(P<0.05)compared with LCFA group.2.Western blot test results:After Western blot imprinting gray were analysised by scion image software,the indicators and GADPH internal value,the area of the gray level ratio as shown in table 5,compared with WT group,the A beta 42,APP and Tau protein levels of three groups of APP/PS1 mice were obviously increased in their hippocampus and cortex tissue(p<0.05).Compared with the LCFA group,the expression levels A beta 42 and Tau protein in the hippocampus and cortex were significantly reduced in the ALA+MCFA group and the MCFA group(p<0.05).A beta 42,APP and Tau protein levels between the ALA + MCFA group and MCFA the two groups had no statistical difference in the cortex(p>0.05),the hippocampus APP,Tau levels also no statistical difference(p>0.05),but A beta 42 protein expression of MCFA group significantly higher(p<0.05).Compared with LCFA group,DBH of serum of ALA+MCFA and MCFA group decreased significantly(P<0.05).There was no significant difference in MAO’s expression level(P>0.05).The expression level of hippocampal TH in the ALA+MCFA group was significantly higher than LCFA group(P<0.05),while there was no statistical difference in the expression level of the brain TH in the MCFA group(P>0.05).3.Immunohistochemical results:Compared with the WT group,the number of A beta plaque(AP)in cerebral hippocampal was significantly increased in the AD model group.Compared with the LCFA group,there were relatively less AP in CA1 and DG areas in the hippocampus of ALA+MCFA and MCFA group.4.Results of high performance liquid chromatography tandem mass spectrometry show that:compared with the LCFA group,the serum levels of beta hydroxybutyric acid and norepinephrine in the mice of ALA+MCFA and MCFA group were both higher,but the difference was not statistically significant(p>0.05).The brain DA level in the ALA+MCFA group was higher than that in the LCFA group,but the difference was not significant(P>0.05).The brain DA level in the MCFA group was significantly higher than that in the LCFA group(P<0.05).5.Blood lipid detection results:compared with LCFA group,the cholesterol and triglyceride levels in the ALA+MCFA and MCFA group were significantly lower(P<0.05),indicating that both ALA and MCFA could improve the lipid metabolism of the AD model mice.Conclusion1.Morris water maze test results show that the learning and memory function of ALA+ MCFA and MCFA group were superior to LCFA group,and the differences of mean escape latency,times across platform were statistically significant(P<0.05),ALA and MCFA can obviously improve the morris water maze performance in APP/PS1 mice,and MCFA+ ALA group has a better effect.2.Western blot and immunohistochemistry results show that MCFA and ALA can improve the learning and memory function of the APP/PS1 mice by reducing the phosphorylation of Tau protein and the production and deposition of Aβ42 protein.3.The levels of TC and TG in the ALA+MCFA and MCFA groups were significantly lower than that in the LCFA group,indicating that both ALA and MCFA had the effect of improving blood lipids.4.Although the NE level in the combined intervention and MCFA group increased,the former had a higher DA level,but there was no statistical difference compared with the LCFA group.The MCFA could significantly increase the DA level in the brain.The combined intervention also promoted the expression of the key enzyme TH,but inhibits the expression of DBH.