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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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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DOI: https://doi.org/10.1007/s12035-015-9425-6