Research On The Molecular Mechanism Of Icariin Against Brain Energy Metabolism Disorders In Alzheimer’s Disease Based On Non-canonical Wnt Signaling Pathway

Objective:To investigate whether icariin（ICA）up-regulates the non-canonical Wnt signaling pathway to promote energy metabolism and improve the learning and memory function of APP/PS1/Tau triple transgenic Alzheimer’s disease AD（3×Tg-AD）mice.Methods:Three-month-old male 3×Tg-AD model mice were randomly divided into 2groups（N=10/group）:3×Tg-AD and 3×Tg-AD+ICA 60 mg/kg);same sex and same month wild type（WT）mice were randomly divided into 2 groups（N=10/group）:WT and WT+ICA 60 mg/kg.Mice in the ICA administration group were given ICA 60 mg/kg by gavage,and 3×Tg-AD group and WT control group mice were given equal volume of vehicle（0.5%Tween 80 distilled water）,once a day,for 5 months.After the administration:Y maze and open field experiments were used to test the memory ability and autonomous exploration behavior of mice.Nissl staining and hematoxylin-eosin（HE）staining were used to observe the morphology and structure of hippocampal neurons in the mouse brain;Immunofluorescence technique was used to detect the accumulation of amyloidβ（Aβ）in the hippocampus of the mouse brain.Colorimetric method was used to detect the content of adenosine triphosphate（ATP）,an energy substance in the hippocampus of mice.Western blot was used to detect the rate-limiting enzymes in the glycolysis pathway of mouse hippocampus:HK1,PFK1,PKM1（subtypes of HK,PFK and PK respectively）;the key enzyme in the second stage of aerobic oxidation pathway:PDC;oxidation key enzymes of phosphorylation pathway:protein expression of mitochondrial respiratory chain cytochrome reductase（COXIII）and cytochrome oxidase（COXIV）;non-canonical Wnt signaling pathway related molecules:protein expression of ligand Wnt5a,dynamin related protein（DRP）,calcium/calmodulin dependent protein kinase kinaseⅡ(Ca²⁺/calmodulin dependent protein kinaseⅡ,Ca MKKⅡ),protein kinase C（protein kinase C,PKC）phosphorylation level.Results:（1）The results of the study showed that compared with WT mice,the learning and memory ability and autonomous exploration behavior of 3×Tg-AD model mice were significantly reduced,accompanied by a decrease in the number of neurons in the hippocampus CA3 and DG regions,cell structure damage and an increase in Aβdeposition,the above phenomenon was significantly improved after ICA administration.At the same time,the ATP content in the hippocampus of 3×Tg-AD mice was significantly lower than those of WT mice,and the above situation was improved after ICA administration.In addition,western blot results showed that compared with WT mice,the protein expression of key enzymes（HK1,PKM1）in the glycolysis pathway of the hippocampus of 3×Tg-AD model mice was significantly decreased after ICA administration,while the expression of PFK1 the protein expression did not change between the groups;the key enzymes of the second stage of aerobic oxidation:PDC,COXIII and COXIV;non-canonical Wnt signaling pathway related molecules（Wnt5a and DRP,Ca MKKⅡ,PKC phosphorylation sites）were also significantly lower than that of the WT group,and the above-mentioned protein expression increased significantly after ICA administration.Conclusion:The protective mechanism of ICA on the central nervous system of3×Tg-AD mice may be related to the upregulation of non-canonical Wnt signaling pathways to improve brain energy metabolism disorders.