Evaluation of Brain Metabolism and Neuroinflammation in Mice with Alzheimer's Disease Treated by Ketogenic Diet by 18F-FDG and 18F-DPA-714 Micro PET/CT
Purpose To investigate whether ketogenic diet(KD)can promote cognition by regulating brain metabolism and neuroinflammation in Alzheimer's disease model mice.Materials and Methods Twenty male APP/PS1 mice were randomly assigned to either a KD group(APP/PS1+KD)or a regular diet group(APP/PS1),with 10 mice in each group.Additionally,10 wild-type C57BL/6 male mice served as the control group.The APP/PS1+KD group was fed with a ketogenic feed,the APP/PS1 group received a regular diet,and the control group was maintained on standard chow for a duration of 4 months.Blood ketone levels of mice were monitored after 4 weeks and 4 months of continuous feeding.Cognitive function was assessed via the morris water maze.18F-FDG and 18F-DPA-714 micro PET/CT were performed to evaluate the effects of KD on glucose metabolism and neuroinflammation across various brain regions in the Alzheimer's disease mice.Following PET/CT imaging,brain tissue samples were collected,and the hippocampal Cal region was selected for paraffin sectioning to detect the expression of glial fibrillary acidic protein and ionized calcium-binding adapter molecule 1 through immunofluorescence analysis.Results In the Morris water maze in the fourth month,compared with the control group,the APP/PS1 group had a significantly longer escape latency on days 3-4(P<0.05 or P<0.01).Compared with the control group,the APP/PS1 group showed a significant decrease in relative 18F-FDG uptake in brain regions such as the striatum,hippocampus,dorsal thalamus,central gray matter,superior colliculus,olfactory bulb,and midbrain(P<0.01,P<0.05).Compared with the APP/PS1 group,the APP/PS1+KD group showed a significant increase in relative 18F-FDG uptake in the hippocampus and dorsal thalamus(P<0.01).Compared with the control group,the APP/PS1 group showed a significant increase in relative uptake of 18F-DPA-714 in brain regions such as the striatum,hippocampus and hypothalamus(P<0.05 or P<0.001).Compared with the APP/PS1 group,the APP/PS1+KD group decreased the relative uptake of 18F-DPA-714 in the hippocampus(P<0.01).Compared with the control group and APP/PS1+KD group,the fluorescence intensity of glial fibrillary acidic protein and ionized calcium-binding adapter molecule 1 protein in the brain(hippocampus)of APP/PS1 group mice was significantly increased(both P<0.01).Conclusion KD has the potential to ameliorate cognitive and behavioral deficits in APP/PS1 mice by enhancing brain metabolism and attenuating neuroinflammation.