Dataset Information

Chronic low dose of AM404 ameliorates the cognitive impairment and pathological features in hyperglycemic 3xTg-AD mice.

ABSTRACT:

Rationale

Hyperglycemia accelerates the progression of Alzheimer's disease (AD), and GSK3? plays a potential link between AD and hyperglycemia. Therefore, a direct or indirect GSK3? inhibition may have potential to delay the progression of AD. Our previous biochemical assay identified AM404 as a GSK3? inhibitor at high dose (IC50?=?5.353 ?M); however, other study suggests that AM404 impaired synaptic plasticity of hippocampus at high dose (10 mg/kg; i.p.). Therefore, the dose and duration of treatment are crucial for the effects of AM404.

Objective

The effects and molecular mechanisms of AM404 at low dose were evaluated from in vitro to in vivo models.

Methods

AM404 (0.1-0.5 ?M) was tested on tau hyperphosphorylated mouse hippocampal primary cultures treated with Wortmannin (WT) and GF109203X (GFX). Hyperglycemic triple transgenic AD (3×Tg-AD) mice at 6 months old were intraperitoneally injected with AM404 (0.25 mg/kg) for 4 weeks. The spatial learning and memory of mice were measured using the Morris water maze. Mouse brain and serum samples were collected for pathological analyses.

Results

AM404 (0.5 ?M) exhibited significantly augmented neuroprotection toward tau hyperphosphorylation in primary cultures. The chronic systemic administration of AM404 (0.25 mg/kg) attenuated cognitive deficits in hyperglycemic 3×Tg-AD mice. Moreover, chronic low dose of AM404 significantly attenuated A? production, tau protein phosphorylation, and inflammation associated with an increase of pS473Akt and pS9-GSK3?. Therefore, AM404 at low dose, not only increased neuroprotection, but also ameliorated cognitive deficit, could be partly by regulating the Akt/GSK3? signaling, which may contribute to downregulation of A?, tau hyperphosphorylation, and inflammation in hyperglycemic 3×Tg-AD mice.

Conclusions

These results highlight that chronic administration of AM404 at low dose may be through the Akt/GSK3? pathway to ameliorate the impairment in hyperglycemic 3×Tg-AD mice.

SUBMITTER: Huang HJ

PROVIDER: S-EPMC6469654 | biostudies-literature | 2019 Feb

REPOSITORIES: biostudies-literature

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Publications

Chronic low dose of AM404 ameliorates the cognitive impairment and pathological features in hyperglycemic 3xTg-AD mice.

Huang Hei-Jen HJ Chen Shu-Ling SL Huang Hsin-Yu HY Sun Ying-Chieh YC Lee Guan-Chiun GC Lee-Chen Guey-Jen GJ Hsieh-Li Hsiu Mei HM Su Ming-Tsan MT

Psychopharmacology 20181113 2

<h4>Rationale</h4>Hyperglycemia accelerates the progression of Alzheimer's disease (AD), and GSK3β plays a potential link between AD and hyperglycemia. Therefore, a direct or indirect GSK3β inhibition may have potential to delay the progression of AD. Our previous biochemical assay identified AM404 as a GSK3β inhibitor at high dose (IC50 = 5.353 μM); however, other study suggests that AM404 impaired synaptic plasticity of hippocampus at high dose (10 mg/kg; i.p.). Therefore, the dose and duratio ...[more]

PMID: 30426182

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Project description:GluA1, GluA2, GluA3, and GluA4 are the constitutive subunits of amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs), the major mediators of fast excitatory transmission in the mammalian central nervous system. Most AMPARs are Ca(2+)-impermeable because of the presence of the GluA2 subunit. GluA2 mRNA undergoes an editing process that results in a Q-R substitution, a key factor in the regulation of AMPAR Ca(2+)-permeability. AMPARs lacking GluA2 or containing the unedited subunit are permeable to Ca(2+) and Zn(2+). The phenomenon physiologically modulates synaptic plasticity while, in pathologic conditions, leads to increased vulnerability to excitotoxic neuronal death. Given the importance of these subunits, we have therefore evaluated possible associations between changes in expression levels of AMPAR subunits and development of cognitive deficits in 3xTg-AD mice, a widely investigated transgenic mouse model of Alzheimer's disease (AD). With quantitative real-time PCR analysis, we assayed hippocampal mRNA expression levels of GluA1-4 subunits occurring in young [3?months of age (m.o.a.)] and old (12 m.o.a) Tg-AD mice and made comparisons with levels found in age-matched wild type (WT) mice. Efficiency of GluA2 RNA editing was also analyzed. All animals were cognitively tested for learning short- and long-term spatial memory with the Morris Water Maze (MWM) navigation task. 3xTg-AD mice showed age-dependent decreases of mRNA levels for all the AMPAR subunits, with the exception of GluA2. Editing remained fully efficient with aging in 3xTg-AD and WT mice. A one-to-one correlation analysis between MWM performances and GluA1-4 mRNA expression profiles showed negative correlations between GluA2 levels and MWM performances in young 3xTg-AD mice. On the contrary, positive correlations between GluA2 mRNA and MWM performances were found in young WT mice. Our data suggest that increases of AMPARs that contain GluA1, GluA3, and GluA4 subunits may help in maintaining cognition in pre-symptomatic 3xTg-AD mice.

Dataset Information

Chronic low dose of AM404 ameliorates the cognitive impairment and pathological features in hyperglycemic 3xTg-AD mice.

Rationale

Objective

Methods

Results

Conclusions

Publications

Chronic low dose of AM404 ameliorates the cognitive impairment and pathological features in hyperglycemic 3xTg-AD mice.

Similar Datasets

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