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Activation of mTOR signaling mediates the increased expression of AChE in high glucose condition: in vitro and in vivo evidences

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Abstract

Acetylcholinesterase (AChE) is impaired in brain of diabetic animals, which may be one of the reasons for diabetes-associated cognitive decline. However, the mechanism is still unknown. The present study was designed to investigate whether the increased expression of AChE in central neurons under high glucose (HG) condition was due to activation of mammalian target of rapamycin (mTOR) signaling. It was found that more production of reactive oxygen species, and higher levels of phospho-Akt, phospho-mTOR, phospho-p70S6K, and AChE were detected in HT-22 cells in HG group than normal glucose group after culture for 24 h, which were all attenuated by an antioxidant N-acetyl-l-cysteine. A PI3K inhibitor LY294002 significantly decreased the levels of phospho-Akt, phospho-mTOR, phospho-p70S6K, and AChE protein expression in HG-cultured HT-22 cells, and an mTOR inhibitor rapamycin markedly reduced the levels of phospho-mTOR, phospho-p70S6K, and AChE expression. Furthermore, compared with normal rats, diabetic rats showed remarkable increases in levels of AChE activity and expression, malondialdehyde, phospho-mTOR, phospho-p70S6K, and a significant decrease in total superoxide dismutase activity in both hippocampus and cerebral cortex. However, much lower levels of phospho-mTOR, phospho-p70S6K, and AChE expression occurred in both brain regions of diabetic rats treated with rapamycin when compared with untreated ones. These results indicated that mTOR signaling was activated through the activation of PI3K/Akt pathway mediated by oxidative stress in HG-cultured HT-22 cells and diabetic rat brains, which contributed to the elevated protein expression of AChE in central neurons under the condition of HG.

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Abbreviations

AChE:

Acetylcholinesterase

Cont:

Control

DACD:

Diabetes-associated cognitive decline

DCFH-DA:

2′,7′-Dichlorofluorescein diacetate

DM:

Diabetes mellitus

DMSO:

Dimethylsulfoxide

HG:

High glucose

HPLC:

High-performance liquid chromatography

LY:

LY294002

MDA:

Malondialdehyde

mTOR:

Mammalian target of rapamycin

NAC:

N-Acetyl-l-cysteine

NG:

Normal glucose

p70S6K:

p70 ribosomal S6 protein kinase

PI3K:

Phosphatidylinositol 3 kinase

Rap:

Rapamycin

ROS:

Reactive oxygen species

STZ:

Streptozotocin

T-SOD:

Total superoxidase dismutase

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Acknowledgments

The work was supported through funding from the Natural Science Foundation of China (81371210) and Qing Lan Project, China, and a project funded through the Priority Academic Program Development of Jiangsu Higher Education Institutions, China.

Conflict of Interest

The authors have declared that there is no conflict of interest.

Compliance with Ethical Standards

All animal experiments were approved through the Animal Ethics Committee of Xuzhou Medical College. All experiments were performed according to the Guidelines for Ethical Conduct in the Care and Use of Animals.

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    Authors and Affiliations

    1. Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical College, No. 209, Tongshan Road, Xuzhou, 221004, Jiangsu, China

      Yao-Wu Liu, Liang Zhang, Yu Li, Ya-Qin Cheng, Xia Zhu, Fan Zhang & Xiao-Xing Yin

    2. Department of Pharmacy, the People’s Hospital of Hebi, Henan, China

      Liang Zhang

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    Correspondence to Xiao-Xing Yin.

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    Yao-Wu Liu and Liang Zhang contributed equally to this work.

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    Liu, YW., Zhang, L., Li, Y. et al. Activation of mTOR signaling mediates the increased expression of AChE in high glucose condition: in vitro and in vivo evidences. Mol Neurobiol 53, 4972–4980 (2016). https://doi.org/10.1007/s12035-015-9425-6

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