Effects of a Dehydroevodiamine-Derivative on Synaptic Destabilization and Memory Impairment in the 5xFAD, Alzheimer's Disease Mouse Model

Carboxy-dehydroevodiamine·HCl (cx-DHED) is a derivative of DHED, which improves memory impairment. Carboxyl modification increases solubility in water, indicating that its bioavailability is higher than that of DHED. Cx-DHED is expected to have better therapeutic effects on Alzheimer's disease (AD) than DHED. In this study, we investigated the therapeutic effects of cx-DHED and the underlying mechanism in 5xFAD mice, transgenic (Tg) mouse model of AD model mice. In several behavioral tests, such as Y-maze, passive avoidance, and Morris water maze test, memory deficits improved significantly in cx-DHED-treated transgenic (Tg) mice compared with vehicle-treated Tg mice. We also found that AD-related pathologies, including amyloid plaque deposition and tau phosphorylation, were reduced after the treatment of Tg mice with cx-DHED. We determined the levels of synaptic proteins, such as GluN1, GluN2A, GluN2B, PSD-95 and Rabphilin3A, and Rab3A in the brains of mice of each group and found that GluN2A and PSD-95 were significantly increased in the brains of cx-DHED-treated Tg mice when compared with the brains of Tg-vehicle mice. These results suggest that cx-DHED has therapeutic effects on 5xFAD, AD model mice through the improvement of synaptic stabilization

S100A9 Knockout Decreases the Memory Impairment and Neuropathology in Crossbreed Mice of Tg2576 and S100A9 Knockout Mice Model

Our previous study presented evidence that the inflammation-related S100A9 gene is significantly upregulated in the brains of Alzheimer's disease (AD) animal models and human AD patients. In addition, experiments have shown that knockdown of S100A9 expression improves cognition function in AD model mice (Tg2576), and these animals exhibit reduced amyloid plaque burden. In this study, we established a new transgenic animal model of AD by crossbreeding the Tg2576 mouse with the S100A9 knockout (KO) mouse. We observed that S100A9KO/Tg2576 (KO/Tg) mice displayed an increased spatial reference memory in the Morris water maze task and Y-maze task as well as decreased amyloid beta peptide (Aβ) neuropathology because of reduced levels of Aβ, C-terminal fragments of amyloid precursor protein (APP-CT) and phosphorylated tau and increased expression of anti-inflammatory IL-10 and also decreased expression of inflammatory IL-6 and tumor neurosis factor (TNF)-α when compared with age-matched S100A9WT/Tg2576 (WT/Tg) mice. Overall, these results suggest that S100A9 is responsible for the neurodegeneration and cognitive deficits in Tg2576 mice. The mechanism of S100A9 is able to coincide with the inflammatory process. These findings indicate that knockout of S100A9 is a potential target for the pharmacological therapy of AD. © 2014 Kim et al.1

Amyloid Precursor Protein Binding Protein-1 Modulates Cell Cycle Progression in Fetal Neural Stem Cells

Amyloid precursor protein binding protein-1 (APP-BP1) binds to the carboxyl terminus of the amyloid precursor protein (APP) and serves as the bipartite activation enzyme for the ubiquitin-like protein, NEDD8. In the present study, we explored the physiological role of APP-BP1 in the cell cycle progression of fetal neural stem cells. Our results show that cell cycle progression of the cells is arrested at the G1 phase by depletion of APP-BP1, which results in a marked decrease in the proliferation of the cells. This action of APP-BP1 is antagonistically regulated by the interaction with APP. Consistent with the evidence that APP-BP1 function is critical for cell cycle progression, the amount of APP-BP1 varies depending upon cell cycle phase, with culminating expression at S-phase. Furthermore, our FRET experiment revealed that phosphorylation of APP at threonine 668, known to occur during the G2/M phase, is required for the interaction between APP and APP-BP1. We also found a moderate ubiquitous level of APP-BP1 mRNA in developing embryonic and early postnatal brains; however, APP-BP1 expression is reduced by P12, and only low levels of APP-BP1 were found in the adult brain. In the cerebral cortex of E16 rats, substantial expression of both APP-BP1 and APP mRNAs was observed in the ventricular zone. Collectively, these results indicate that APP-BP1 plays an important role in the cell cycle progression of fetal neural stem cells, through the interaction with APP, which is fostered by phopshorylation of threonine 668

Dehydroevodiamine center dot HCl Protects Against Memory Impairment and Cerebral Amyloid-beta Production in Tg2576 Mice by Acting as a beta-Secretase Inhibitor

We previously demonstrated that dehydroevodiamine•HCl (DHED), which was purified from Evodia rutaecarpa Bentham (Rutaceae), has beneficial effects on memory impairment and neuronal damage in three disease models. To investigate the preventive action of DHED in Alzheimer’s disease (AD), a progressive neurodegenerative disorder characterized by memory decline, amyloid-β (Aβ) protein-containing neuritic plaques and neurofibrillary tangles, in this study, we proposed that DHED may be therapeutically effective against the memory impairment and disease-related neurochemical changes that occur in Tg2576 (Tg) mice. DHED (0.5 mg/kg) was intraperitoneally administered to 7-month-old Tg and wild type mice for 4 months. In passive avoidance and water maze tests, DHED improved memory impairment of Tg mice after 4 months of administration. DHED also reduced cortical levels of soluble Aβ40, soluble Aβ42 and total Aβ peptides in the Tg mice. Additionally, we investigated whether DHED may be a β-secretase inhibitor that affects the production of Aβ related to the formation of neuritic plaques. DHED directly inhibited β-secretase activity in a concentrationdependent manner. The concentration required for 50 % enzyme inhibition (IC50) was 40.96 µM, and DHED may act as a competitive inhibitor of β-secretase. Moreover, DHED interacted strongly with BACE1 (β-secretase 2QP8), as demonstrated in the analysis of the binding mode of DHED in the active site of human BACE1. In conclusion, DHED may exhibit therapeutic effects for AD as a β-secretase inhibitor. © 2016 Bentham Science Publishers.1

S100A9KOxTg crossbred mice showed significant improvement in spatial reference memory.

<p>We performed memory tests at the age of 13-months. (A) The Morris water maze test was performed. Training trials were conducted for 5 consecutive days. From the 5^th day of training trials, escape latency was significantly increased in the WT/Tg group. However, the latency was decreased in the KO/Tg group compared to the WT/Tg group.<i>*p</i><0.05 by one-way ANOVA. (B) The probe test was performed 48 h after the final training session. The times that the mice of each group stayed in zones 1, 2, 3 and 4 were compared. The time spent in the platform quadrant (zone 4) was significantly decreased in the WT/Tg group. However, the KO/Tg group showed memory improvement compared to the WT/Tg group in zone 4. (C) In the Y-maze, the WT/Tg group showed a significant decrease in the alternation rate of arm entries. In the passive avoidance test, the latency time of the KO/Tg group was greatly increased. Behavior task groups were as follows: n = 7–11 per group. These results were analyzed by ANOVA followed by the LSD test <i>*p</i><0.05, <i>**p<</i>0.01.</p

The anti-inflammatory cytokine IL-10 was significantly increased and pro-inflammatory cytokines IL-6 and TNF-α were decreased in the cortex of KO/Tg mice brains compared to WT/Tg mice brains at 14 months old.

<p>(A) The level of IL-10 was detected in the tissue lysates from the cortical region of the brain from each group by sandwich ELISA. IL-10, which is a representative anti-inflammatory cytokine, was increased in the cortex of KO/Tg mice brains compared to WT/Tg mice brains. (B) The level of IL-6 was detected in the tissue lysates from the cortical region of the brain from each group by sandwich ELISA. IL-6, which is a representative pro-inflammatory cytokine, was decreased in the cortex of KO/Tg mice brains compared to WT/Tg mice brains. (C) The level of TNF-α was detected in the tissue lysates from the cortical region of the brain from each group by sandwich ELISA. TNF-α, which is a representative pro-inflammatory cytokine, was decreased in the cortex of KO/Tg mice brains compared to WT/Tg mice brains. (n = 9–10), *<i>p</i><0.05 by one-way ANOVA.</p

Accumulation of phosphorylated tau was detected in neurites surrounding amyloid plaques in the brain of S100A9 crossbred mice at 14 months old.

<p>Phosphorylated tau (P-tau) was detected in the hippocampus and cortex of WT/Tg and KO/Tg mice brains by immunohistochemistry. The amount of P-tau was significantly reduced in KO/Tg mice brains compared with WT/Tg mice brains. (h) – (j) are P-tau stained region of (c) and (g). Sections are 4 µm thick. ((a) – (h) Scale bar; 200 µm, (h) – (k) scale bar; 50 µm).</p

The number of amyloid plaques and amount of Aβ_1-42 were reduced in S100A9 KO/Tg mice.

<p>After the tests, the mice brains were isolated and the brain slices were stained with Congo red for the detection of amyloid plaques. (A) Histological analysis was performed out at the age of 14-months. In the cortex, hippocampus and entorhinal cortex, amyloid plaques were detected using Congo red staining. (i)-(l) The Congo red-stained region of (c), (g) and (h). Thio-S stained region of (m). Sections are 4 µm thick. ((a) – (h) Scale bar; 200 µm, (i)-(l) scale bar; 50 µm). (B) Quantitative analysis of Congo red-stained plaque number. The number of amyloid plaques was counted in brain slices containing the hippocampal region of each group, and the average number of plaques per brain slice was calculated. In brains from the KO/Tg group, Aβ deposition was significantly reduced in the cortex and hippocampus, compared to the WT/Tg group. The total numbers of mice per group were as follows: n = 3–6 per group.<i>*p</i><0.05 by one-way ANOVA. (C, D) Western blot analysis was performed with the total lysates from the cortical region and hippocampal region of brains in each group using the 6E10 antibody. Aβ and CT bands were detected and normalized by the amount of APP and GAPDH. In the WT/Tg mice brain, many Aβ and CT were produced compared to KO/Tg mice. (n = 10). (E, F) Aβ<b>_1-42</b> levels in cortical or hippocampal brain regions in all groups were analyzed by Aβ ELISA. The levels of Aβ<b>_1-42</b> were highly increased in the cortex and hippocampus of WT/Tg mice compared with age-matched WT/WT or WT/KO mice. Note that the levels of Aβ<b>_1-42</b> were decreased in the cortex and hippocampus of KO/Tg mice brains compared with WT/Tg mice brains (n = 4). (G, H) Western blot analysis was performed with total lysates from the cortical region of the brains in each group using an antibody against oligomeric Aβ. In the cortex of KO/Tg mice brains, the relative quantity of oligomeric Aβ was decreased compared with WT/Tg mice. (n = 3) <i>*p</i><0.05 by one-way ANOVA.</p