Maiko Uemura

Exercise Is More Effective than Diet Control in Preventing High Fat Diet-induced β-Amyloid Deposition and Memory Deficit in Amyloid Precursor Protein Transgenic Mice

Background: Exercise and diet control are fundamental approaches to metabolic conditions caused by high fat diet (HFD). Results: HFD-induced memory deficit and Aβ deposition were more ameliorated in the exercise- than in the diet control-induced mice. Conclusion: Exercise was more effective than diet control in preventing HFD-induced AD development. Significance: Exercise has the highest priority in the prevention of AD. Accumulating evidence suggests that some dietary patterns, specifically high fat diet (HFD), increase the risk of developing sporadic Alzheimer disease (AD). Thus, interventions targeting HFD-induced metabolic dysfunctions may be effective in preventing the development of AD. We previously demonstrated that amyloid precursor protein (APP)-overexpressing transgenic mice fed HFD showed worsening of cognitive function when compared with control APP mice on normal diet. Moreover, we reported that voluntary exercise ameliorates HFD-induced memory impairment and β-amyloid (Aβ) deposition. In the present study, we conducted diet control to ameliorate the metabolic abnormality caused by HFD on APP transgenic mice and compared the effect of diet control on cognitive function with that of voluntary exercise as well as that of combined (diet control plus exercise) treatment. Surprisingly, we found that exercise was more effective than diet control, although both exercise and diet control ameliorated HFD-induced memory deficit and Aβ deposition. The production of Aβ was not different between the exercise- and the diet control-treated mice. On the other hand, exercise specifically strengthened the activity of neprilysin, the Aβ-degrading enzyme, the level of which was significantly correlated with that of deposited Aβ in our mice. Notably, the effect of the combination treatment (exercise and diet control) on memory and amyloid pathology was not significantly different from that of exercise alone. These studies provide solid evidence that exercise is a useful intervention to rescue HFD-induced aggravation of cognitive decline in transgenic model mice of AD.

Potential interactions between pericytes and oligodendrocyte precursor cells in perivascular regions of cerebral white matter.

Pericytes are embedded within basal lamina and play multiple roles in the perivascular niche in brain. Recently, oligodendrocyte precursor cells (OPCs) have also been reported to associate with cerebral endothelium. Is it possible that within this gliovascular locus, there may also exist potential spatial and functional interactions between pericytes and OPCs? Here, we demonstrated that in the perivascular region of cerebral white matter, pericytes and OPCs may attach and support each other. Immunostaining showed that pericytes and OPCs are localized in close contact with each other in mouse white matter at postnatal days 0, 60 and 240. Electron microscopic analysis confirmed that pericytes attached to OPCs via basal lamina in the perivascular region. The close proximity between these two cell types was also observed in postmortem human brains. Functional interaction between pericytes and OPCs was assessed by in vitro media transfer experiments. When OPC cultures were treated with pericyte-conditioned media, OPC number increased. Similarly, pericyte number increased when pericytes were maintained in OPC-conditioned media. Taken together, our data suggest a potential anatomical and functional interaction between pericytes and OPCs in cerebral white matter.

Copper enhances APP dimerization and promotes Aβ production.

Alzheimers disease (AD) is characterized by the deposition of amyloid-β (Aβ) plaques, senile plaque. The Aβ peptide is cleaved from amyloid precursor protein (APP) by β-secretase and γ-secretase. Until now, many literatures have documented that the high concentration of copper is present in Aβ plaques and enhances aggregation of. The APP copper binding domain (CuBD) is located in the N-terminal next to the growth factor-like domain that gets involved in APP homodimerization. Importantly, dimerization of APP has profound effect on Aβ production. We investigated whether copper alters the state of APP dimerization and how it affects APP metabolism. Here, we demonstrate that copper enhanced APP dimerization and increased extracellular release of Aβ. Moreover, copper chelator, D-penicillamine, suppressed APP dimerization and decreased extracellular release of Aβ. These results suggest that the action of copper may be profoundly associated with the pathway of Aβ production in AD pathogenesis.

Continuation of exercise is necessary to inhibit high fat diet-induced β-amyloid deposition and memory deficit in amyloid precursor protein transgenic mice.

High fat diet (HFD) is prevalent in many modern societies and HFD-induced metabolic condition is a growing concern worldwide. It has been previously reported that HFD clearly worsens cognitive function in amyloid precursor protein (APP) transgenic mice. On the other hand, we have demonstrated that voluntary exercise in an enriched environment is an effective intervention to rescue HFD-induced β-amyloid (Aβ) deposition and memory deficit. However, it had been unclear whether consumption of HFD after exercising abolished the beneficial effect of exercise on the inhibition of Alzheimers disease (AD) pathology. To examine this question, we exposed wild type (WT) and APP mice fed with HFD to exercise conditions at different time periods. In our previous experiment, we gave HFD to mice for 20 weeks and subjected them to exercise during weeks 10–20. In the present study, mice were subjected to exercise conditions during weeks 0–10 or weeks 5–15 while being on HFD. Interestingly, we found that the effect of exercise during weeks 0–10 or weeks 5–15 on memory function was not abolished in WT mice even if they kept having HFD after finishing exercise. However, in APP transgenic mice, HFD clearly disrupted the effect of exercise during weeks 0–10 or weeks 5–15 on memory function. Importantly, we observed that the level of Aβ oligomer was significantly elevated in the APP mice that exercised during weeks 0–10: this might have been caused by the up-regulation of Aβ production. These results provide solid evidence that continuation of exercise is necessary to rescue HFD-induced aggravation of cognitive decline in the pathological setting of AD.

High Fat Diet Enhances β-Site Cleavage of Amyloid Precursor Protein (APP) via Promoting β-Site APP Cleaving Enzyme 1/Adaptor Protein 2/Clathrin Complex Formation.

Obesity and type 2 diabetes are risk factors of Alzheimer’s disease (AD). We reported that a high fat diet (HFD) promotes amyloid precursor protein (APP) cleavage by β-site APP cleaving enzyme 1 (BACE1) without increasing BACE1 levels in APP transgenic mice. However, the detailed mechanism had remained unclear. Here we demonstrate that HFD promotes BACE1/Adaptor protein-2 (AP-2)/clathrin complex formation by increasing AP-2 levels in APP transgenic mice. In Swedish APP overexpressing Chinese hamster ovary (CHO) cells as well as in SH-SY5Y cells, overexpression of AP-2 promoted the formation of BACE1/AP-2/clathrin complex, increasing the level of the soluble form of APP β (sAPPβ). On the other hand, mutant D495R BACE1, which inhibits formation of this trimeric complex, was shown to decrease the level of sAPPβ. Overexpression of AP-2 promoted the internalization of BACE1 from the cell surface, thus reducing the cell surface BACE1 level. As such, we concluded that HFD may induce the formation of the BACE1/AP-2/clathrin complex, which is followed by its transport of BACE1 from the cell surface to the intracellular compartments. These events might be associated with the enhancement of β-site cleavage of APP in APP transgenic mice. Here we present evidence that HFD, by regulation of subcellular trafficking of BACE1, promotes APP cleavage.

Pericyte-derived bone morphogenetic protein 4 underlies white matter damage after chronic hypoperfusion

Subcortical small vessel disease (SVD) is characterized by white matter damage resulting from arteriolosclerosis and chronic hypoperfusion. Transforming growth factor beta 1 (TGFB1) is dysregulated in the hereditary SVD, CARASIL (cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy). However, very little is known about the role of the largest group in the TGFB superfamily – the bone morphogenetic proteins (BMPs) – in SVD pathogenesis. The aim of this study was to characterize signaling abnormalities of BMPs in sporadic SVD. We examined immunostaining of TGFB1 and BMPs (BMP2/BMP4/BMP6/BMP7/BMP9) in a total of 19 post‐mortem human brain samples as follows: 7 SVD patients (4 males, 76–90 years old); 6 Alzheimers disease (AD) patients (2 males, 67–93 years old) and 6 age‐matched disease controls (3 males, 68–78 years old). We subsequently investigated the effects of oxygen–glucose deprivation and BMP4 addition on cultured cells. Furthermore, adult mice were subjected to chronic cerebral hypoperfusion using bilateral common carotid artery stenosis, followed by continuous intracerebroventricular infusion of the BMP antagonist, noggin. In the SVD cases, BMP4 was highly expressed in white matter pericytes. Oxygen–glucose deprivation induced BMP4 expression in cultured pericytes in vitro. Recombinant BMP4 increased the number of cultured endothelial cells and pericytes and converted oligodendrocyte precursor cells into astrocytes. Chronic cerebral hypoperfusion in vivo also upregulated BMP4 with concomitant white matter astrogliogenesis and reduced oligodendrocyte lineage cells, both of which were suppressed by intracerebroventricular noggin infusion. Our findings suggest ischemic white matter damage evolves in parallel with BMP4 upregulation in pericytes. BMP4 promotes angiogenesis, but induces astrogliogenesis at the expense of oligodendrocyte precursor cell proliferation and maturation, thereby aggravating white matter damage. This may explain white matter vulnerability to chronic hypoperfusion. The regulation of BMP4 signaling is a potential therapeutic strategy for treating SVD.

Zonisamide inhibits monoamine oxidase and enhances motor performance and social activity

Zonisamide (ZNS) is an effective drug for not only motor symptoms but also non-motor symptoms in Parkinsons disease. However, the actions of ZNS as an anti-Parkinsonian drug are not well understood. To clarify the actions of ZNS in vivo, we administered ZNS to mice and examined the effects on neurotransmitter metabolism and behaviors, focusing on motor and non-motor symptoms. Administration of ZNS decreased dopamine (DA) turnover in various brain regions, including the striatum. In behavioral tests, ZNS enhanced locomotor activity and novelty seeking in the open field test, light-dark transition test, and the social interaction test. Consistent with these results of DA metabolism in ZNS-treated mice, monoamine oxidase activity was significantly inhibited by ZNS in primary neurons and astrocytes. Collectively, these data suggest that ZNS inhibits monoamine oxidase activity and decreases DA turnover, which increases locomotor activity and novelty seeking in mice. ZNS is potentially useful to improve not only motor symptoms but also neuropsychiatric non-motor symptoms such as apathy in PD.

Prolonged sensory impairment in the perineal region after painless delivery through lumbar epidural anesthesia

In the painless delivery, the neuronal injury caused by regional anesthesia sometimes causes diagnostic difficulty because of the common findings with lumbosacral injury due to vaginal delivery. We herein report a 36‐year‐old woman presenting with long‐standing cauda equina syndrome due to neurotoxicity of regional anesthetic. Neurological examination revealed the almost symmetrical, heterogeneous sensory deficit mainly in the perineal region, hypoactive quadriceps femoris reflex, decreased anal sphincter reflex, and dermographia. The correct diagnosis is important to support the quality of life of patients.