Long-term running exercise improves cognitive function and promotes microglial glucose metabolism and morphological plasticity in the hippocampus of APP/PS1 mice.

BACKGROUND: The role of physical exercise in the prevention of Alzheimer's disease (AD) has been widely studied. Microglia play an important role in AD. Triggering receptor expressed in myeloid cells 2 (TREM2) is expressed on microglia and is known to mediate microglial metabolic activity and brain glucose metabolism. However, the relationship between brain glucose metabolism and microglial metabolic activity during running exercise in APP/PS1 mice remains unclear. METHODS: Ten-month-old male APP/PS1 mice and wild-type mice were randomly divided into sedentary groups or running groups (AD_Sed, WT_Sed, AD_Run and WT_Run, n = 20/group). Running mice had free access to a running wheel for 3 months. Behavioral tests, [18]F-FDG-PET and hippocampal RNA-Seq were performed. The expression levels of microglial glucose transporter (GLUT5), TREM2, soluble TREM2 (sTREM2), TYRO protein tyrosine kinase binding protein (TYROBP), secreted phosphoprotein 1 (SPP1), and phosphorylated spleen tyrosine kinase (p-SYK) were estimated by western blot or ELISA. Immunohistochemistry, stereological methods and immunofluorescence were used to investigate the morphology, proliferation and activity of microglia. RESULTS: Long-term voluntary running significantly improved cognitive function in APP/PS1 mice. Although there were few differentially expressed genes (DEGs), gene set enrichment analysis (GSEA) showed enriched glycometabolic pathways in APP/PS1 running mice. Running exercise increased FDG uptake in the hippocampus of APP/PS1 mice, as well as the protein expression of GLUT5, TREM2, SPP1 and p-SYK. The level of sTREM2 decreased in the plasma of APP/PS1 running mice. The number of microglia, the length and endpoints of microglial processes, and the ratio of GLUT5+/IBA1+ microglia were increased in the dentate gyrus (DG) of APP/PS1 running mice. Running exercise did not alter the number of 5-bromo-2'-deoxyuridine (BrdU)+/IBA1+ microglia but reduced the immunoactivity of CD68 in the hippocampus of APP/PS1 mice. CONCLUSIONS: Running exercise inhibited TREM2 shedding and maintained TREM2 protein levels, which were accompanied by the promotion of brain glucose metabolism, microglial glucose metabolism and morphological plasticity in the hippocampus of AD mice. Microglia might be a structural target responsible for the benefits of running exercise in AD. Promoting microglial glucose metabolism and morphological plasticity modulated by TREM2 might be a novel strategy for AD treatment.

Anti-LINGO-1 antibody ameliorates cognitive impairment, promotes adult hippocampal neurogenesis, and increases the abundance of CB1R-rich CCK-GABAergic interneurons in AD mice.

In view of the negative regulatory effect of leucine-rich repeat and immunoglobulin-like domain-containing nogo receptor-interacting protein 1 (LINGO-1) on neurons, an antibody against LINGO-1 (anti-LINGO-1 antibody) was herein administered to 10-month-old APP/PS1 transgenic Alzheimer's disease (AD) mice for 2 months as an experimental intervention. Behavioral, stereology, immunohistochemistry and immunofluorescence analyses revealed that the anti-LINGO-1 antibody significantly improved the cognitive abilities, promoted adult hippocampal neurogenesis (AHN), decreased the amyloid beta (Aß) deposition, enlarged the hippocampal volume, and increased the numbers of total neurons and GABAergic interneurons, including GABAergic and CCK-GABAergic interneurons rich in cannabinoid type 1 receptor (CB1R), in the hippocampus of AD mice. In contrast, this intervention significantly reduced the number of GABAergic interneurons expressing LINGO-1 and CB1R in the hippocampus of AD mice. More importantly, we also found a negative correlation between LINGO-1 and CB1R on GABAergic interneurons in the hippocampus of AD mice, while the anti-LINGO-1 antibody reversed this relationship. These results indicated that LINGO-1 plays an important role in the process of hippocampal neuron loss in AD mice and that antagonizing LINGO-1 can effectively prevent hippocampal neuron loss and promote AHN. The improvement in cognitive abilities may be attributed to the improvement in AHN, and in the numbers of GABAergic interneurons and CCK-GABAergic interneurons rich in CB1Rs in the hippocampus of AD mice induced by the anti-LINGO-1 antibody. Collectively, the double target effect (LINGO-1 and CB1R) initiated by the anti-LINGO-1 antibody may provide an important basis for the study of drugs for the prevention and treatment of AD in the future.

Four-month treadmill exercise prevents the decline in spatial learning and memory abilities and the loss of spinophilin-immunoreactive puncta in the hippocampus of APP/PS1 transgenic mice.

BACKGROUND: Previous studies have reported that exercise could improve the plasticity of hippocampal synapses. However, the effects of exercise on synapses in the hippocampus in Alzheimer's disease (AD) are not completely known. METHODS: In this study, thirty 12-month-old male APP/PS1 double transgenic mice were randomly divided into a sedentary group (n = 15) and a running group (n = 15). Fifteen 12-month-old male wild-type littermates were assigned to the control group (n = 15). While running mice were assigned to treadmill running for four months, the control mice and sedentary mice did not run during the study period. After Morris water maze testing, five mice in each group were randomly selected for a stereological assessment of spinophilin-immunoreactive puncta in the CA1, CA2-3 and dentate gyrus (DG) of the hippocampus. RESULTS: Morris water maze testing revealed that while the learning and memory abilities in sedentary APP/PS1 mice were significantly worse than those in wild-type control mice, the learning and memory abilities in running APP/PS1 mice were significantly better than those in sedentary APP/PS1 mice. The stereological results showed that the spinophilin-immunoreactive puncta numbers of the CA1, CA2-3 and DG in the hippocampus of sedentary APP/PS1 mice were significantly lower than those of wild-type control mice and that the numbers of these spines in the CA1, CA2-3 and DG in the hippocampus of running APP/PS1 mice were significantly higher than those of sedentary APP/PS1 mice. Moreover, a running-induced improvement in spatial learning and memory abilities was significantly correlated with running-induced increases in the spinophilin-immunoreactive puncta numbers in the CA1 and DG of the hippocampus. CONCLUSIONS: Four-month treadmill exercise induced a significant improvement in spatial learning and memory abilities and a significant increase in the number of spinophilin-immunoreactive puncta of the CA1, CA2-3 and DG in the hippocampus of APP/PS1 mice. Running-induced improvements in spatial learning and memory abilities were significantly correlated with running-induced increases in the spinophilin-immunoreactive puncta numbers in the CA1 and DG of the hippocampus.

Synthesis of Terminal Vinylindoles via RhIII -Catalyzed Direct C-H Alkenylation with Potassium Vinyltrifluoroborate.

An efficient RhIII -catalyzed direct C2-alkenylation of indoles using readily available potassium vinyltrifluoroborate under mild conditions has been developed. This protocol features wide substrate scope and excellent functional group compatibility, enabling a facile access to diverse terminal vinylindoles in moderate to good yields. Furthermore, the C2-alkenylated indole can be easily transformed into 9H-carbazole through a ring-closing metathesis/aromatization cascade.

Antagonizing LINGO-1 reduces activated microglia and alleviates dendritic spine loss in the hippocampus of APP/PS1 transgenic mice.

In Alzheimer's disease (AD), microglia are involved in synaptic pruning and mediate synapse loss. LINGO-1 is a negative regulator of nerve growth, and whether antagonizing LINGO-1 can attenuate synaptic pruning by microglia and rescue dendritic spines in the hippocampus in AD is still unclear. On this basis, the anti-LINGO-1 antibody, which binds to LINGO-1 protein and antagonizes the effects of LINGO-1, was administered to 10-month-old APP/PS1 transgenic mice for 2 months. The Morris water maze test, immunohistochemical and stereological methods, immunofluorescence and 3D reconstruction were used. Compared to wild-type mice, APP/PS1 transgenic mice had worse performance on behavioral tests, fewer dendritic spines but more microglia in the hippocampus. Meanwhile, the microglia in APP/PS1 transgenic mice had more branches of medium length (4-6 µm) and a cell body area with greater variability. Moreover, APP/PS1 transgenic mice had more postsynaptic termini colocalized with microglia in the hippocampus than wild-type mice. The anti-LINGO-1 antibody significantly reversed these changes in AD, indicating that the anti-LINGO-1 antibody can improve hippocampus-dependent learning and memory abilities and effectively rescue dendritic spines in the hippocampus of AD mice and that microglia might participate in this progression in AD. These results provide a scientific basis for further studying the mechanism of the anti-LINGO-1 antibody in AD and help to elucidate the role of LINGO-1 in the treatment of AD.

Anti-LINGO-1 antibody protects neurons and synapses in the medial prefrontal cortex of APP/PS1 transgenic mice.

The medial prefrontal cortex (mPFC), one of the most vulnerable brain regions in Alzheimer's disease (AD), plays a critical role in cognition. Leucine-rich repeat and immunoglobulin-like domain-containing nogo receptor-interacting protein-1 (LINGO-1) negatively affects nerve growth in the central nervous system; however, its role in the pathological damage to the mPFC remains to be studied in AD. In this study, an anti-LINGO-1 antibody was administered to 10-month-old APP/PS1 mice, and behavioral tests, stereological methods, immunohistochemistry and immunofluorescence were used to answer this question. Our results revealed that LINGO-1 was highly expressed in the neurons of the mPFC of AD mice, and the anti-LINGO-1 antibody improved prefrontal cortex-related function and reduced the protein level of LINGO-1, atrophy of the volume, Aß deposition and massive losses of synapses and neurons in the mPFC of AD mice. Antagonizing LINGO-1 could effectively alleviate the pathological damage in the mPFC of AD mice, which might be an important structural basis for improving prefrontal cortex-related function. Abnormal expression of LINGO-1 in the mPFC may be one of the key targets of AD, and the effect initiated by the anti-LINGO-1 antibody may provide an important basis in the search for drugs for the prevention and treatment of AD.

Running exercise protects spinophilin-immunoreactive puncta and neurons in the medial prefrontal cortex of APP/PS1 transgenic mice.

The medial prefrontal cortex (mPFC) is thought to be closely associated with emotional processes, decision making, and memory. Previous studies have identified the prefrontal cortex as one of the most vulnerable brain regions in Alzheimer's disease (AD). Running exercise has widely been recognized as a simple and effective method of physical activity that enhances brain function and slows the progression of AD. However, the effect of exercise on the mPFC of AD is unclear. To address these issues, we investigated the effects of 4 months of exercise on the numbers of spinophilin-immunoreactive puncta and neurons in the mPFC of 12-month-old APPswe/PSEN1dE9 (APP/PS1) transgenic AD model mice using stereological methods. The spatial learning and memory abilities of mice were tested using the Morris water maze. Four months of running exercise delayed declines in spatial learning and memory abilities. The stereological results showed significantly lower numbers of spinophilin-immunoreactive puncta and neurons in the mPFC of APP/PS1 mice than in the wild-type control group. The numbers of spinophilin-immunoreactive puncta and neurons in the mPFC of running APP/PS1 mice were significantly greater than those in the APP/PS1 control mice. In addition, running-induced improvements in spatial learning and memory were significantly associated with running-induced increases in spinophilin-immunoreactive puncta and neurons numbers in the mPFC. Running exercise could delay the loss of spinophilin-immunoreactive puncta and neurons in the mPFC of APP/PS1 mice. This finding might provide an important structural basis for exercise-induced improvements in the spatial learning and memory abilities of individuals with AD.

Exercise more efficiently regulates the maturation of newborn neurons and synaptic plasticity than fluoxetine in a CUS-induced depression mouse model.

Depression, a common and important cause of morbidity and mortality worldwide, is commonly treated with antidepressants, electric shock and psychotherapy. Recently, increasing evidence has shown that exercise can effectively alleviate depression. To determine the difference in efficacy between exercise and the classic antidepressant fluoxetine in treating depression, we established four groups: the Control, chronic unpredictable stress (CUS/STD), running (CUS/RUN) and fluoxetine (CUS/FLX) groups. The sucrose preference test (SPT), the forced swimming test (FST), the tail suspension test (TST), immunohistochemistry, immunofluorescence and stereological analyses were used to clarify the difference in therapeutic efficacy and mechanism between exercise and fluoxetine in the treatment of depression. In the seventh week, the sucrose preference of the CUS/RUN group was significantly higher than that of the CUS/STD group, while the sucrose preference of the CUS/FLX group did not differ from that of the CUS/STD group until the eighth week. Exercise reduced the immobility time in the FST and TST, while fluoxetine only reduced immobility time in the TST. Hippocampal structure analysis showed that the CUS/STD group exhibited an increase in immature neurons and a decrease in mature neurons. Exercise reduced the number of immature neurons and increased the number of mature neurons, but no increase in the number of mature neurons was observed after fluoxetine treatment. In addition, both running and fluoxetine reversed the decrease in the number of MAP2+ dendrites in depressed mice. Exercise increased the number of spinophilin-positive (Sp+) dendritic spines in the hippocampal CA1, CA3, and dentate gyrus (DG) regions, whereas fluoxetine only increased the number of SP+ spines in the DG. In summary, exercise promoted newborn neuron maturation in the DG and regulated neuronal plasticity in three hippocampal subregions, which might explain why running exerts earlier and more comprehensive antidepressant effects than fluoxetine.

Anti-LINGO-1 antibody treatment alleviates cognitive deficits and promotes maturation of oligodendrocytes in the hippocampus of APP/PS1 mice.

Leucine-rich repeat and immunoglobulin-like domain-containing nogo receptor-interacting protein 1 (LINGO-1), a negative regulator of oligodendrocyte differentiation and myelination, is associated with cognitive function, and its expression is highly upregulated in Alzheimer's disease (AD) patients. Anti-LINGO-1 antibody treatment can effectively antagonize the negative regulatory effect of LINGO-1. In this study, we aim to assess the effect of anti-LINGO-1 antibody treatment on cognition and hippocampal oligodendrocytes in an AD transgenic animal model. First, 10-month-old male amyloid-ß (Aß) protein precursor (APP)/presenilin 1 (PS1) mice were administered anti-LINGO-1 antibody for 8 weeks. Then, learning and memory abilities were assessed with the Morris water maze (MWM) and Y-maze tests, and Aß deposition and hippocampal oligodendrocytes were investigated by immunohistochemistry, immunofluorescence, and stereology. We found that anti-LINGO-1 antibody alleviated the deficits in spatial learning and memory abilities and working and reference memory abilities, decreased the density of LINGO-1 positive cells, decreased Aß deposition, significantly increased the number of mature oligodendrocytes and the density of myelin, reversed the abnormal increases in the number of oligodendrocyte lineage cells and the densities of oligodendrocytes precursor cells in APP/PS1 mice. Our results provide evidence that LINGO-1 might be involved in the process of oligodendrocyte dysmaturity in the hippocampus of AD mice, and that antagonizing LINGO-1 can alleviate cognitive deficits in APP/PS1 mice and decrease Aß deposition and promote oligodendrocyte differentiation and maturation in the hippocampus of these mice. Our findings suggest that changes in LINGO-1 and oligodendrocytes in the hippocampus play important roles in the pathogenesis of AD and that antagonizing LINGO-1 might be a potential therapeutic strategy for AD.

Atrophy of lacunosum moleculare layer is important for learning and memory in APP/PS1 transgenic mice.

Changes in the hippocampus are closely associated with learning and memory in Alzheimer's disease; however, it is not clear which morphological and cellular and subcellular changes are essential for learning and memory. Here, we accurately quantitatively studied the hippocampal microstructure changes in Alzheimer's disease model mice and analyzed the relationship between the hippocampal microstructure changes and learning and memory. Ten-month-old male APP/PS1 transgenic mice and age-matched nontransgenic littermate mice were randomly selected. The spatial learning and memory abilities were assessed using the Morris water maze. The volumes of each layer and numbers of neurons, dendritic spines and oligodendrocytes in the hippocampal subregions were investigated using unbiased stereological techniques. The APP/PS1 transgenic mice showed a decline in hippocampus-dependent spatial learning and memory abilities, smaller volumes of each layer (other than stratum radiatum) and fewer numbers of neurons, dendritic spine synapses and mature oligodendrocytes in the hippocampal subregions than nontransgenic mice. In particular, the decline of spatial learning ability was significantly correlated with the atrophy of lacunosum moleculare layer (LMol) and the decrease of hippocampal neurons and mature oligodendrocytes rather than dendritic spines. The CA1-3 fields (including LMol) atrophy was significantly correlated with the decrease both of neurons, dendritic spines and mature oligodendrocytes. However, the dentate gyrus atrophy was significantly correlated with the decrease of neurons and mature oligodendrocytes rather than dendritic spines. The loss of neurons, dendritic spines synapses and mature oligodendrocytes together caused the LMol atrophy and then led to a decline in hippocampus-dependent spatial learning ability in mice with Alzheimer's disease.