Abstract
Cerebral hypoglycemia/hypometabolism is associated with Alzheimer’s disease (AD) and is routinely used to assist clinical diagnosis of AD by brain imaging. However, whether cerebral hypoglycemia/hypometabolism contributes to the development of AD or is a response of reduced neuronal activity remains unclear. To investigate the causal relationship, we cultured the differentiated N2a neuroblastoma cells in glucose/pyruvate-deficient media (GDM). Shortly after the N2a cells cultured in the GDM, the mitochondria membrane potential was reduced and the AMP-activated-proteinkinase (AMPK), an energy sensor, was activated. Treatment of GDM not only increased the levels of tau phosphorylation at Ser262 and Ser396, but also increased the levels of active forms of GSK3α and GSK3β, two known kinases for tau phosphorylation, of the N2a cells. The levels of activated Akt, a mediator downstream to AMPK and upstream to GSK3α/β, were reduced by the GDM treatment. The effect of hypoglycemia was further examined in vivo by intracerebroventricular (icv) injection of streptozotocin (STZ) to the Wistar rats. STZ selectively injuries glucose transporter type 2-bearing cells which are primarily astrocytes in the rat brain, hence, interrupts glucose transportation from blood vessel to neuron. STZicv injection induced energy crisis in the brain regions surrounding the ventricles, as indicated by higher pAMPK levels in the hippocampus, but not cortex far away from the ventricles. STZ-icv treatment increased the levels of phosphorylated tau and activated GSK3β, but decreased the levels of activated Akt in the hippocampus. The hippocampus-dependent spatial learning and memory was impaired by the STZ-icv treatment. In conclusion, our works suggest that hypoglycemia enhances the AMPK-Akt-GSK3 pathway and leads to tau hyperphosphorylation.
Keywords: Alzheimer’s disease, hypoglycemia, AMPK, Akt, GSK3, tau
Current Alzheimer Research
Title:Hypoglycemia Induces Tau Hyperphosphorylation
Volume: 10 Issue: 3
Author(s): Chu-Wan Lee, Yao-Hsiang Shih, Shih-Ying Wu, Tingting Yang, Chingju Lin and Yu-Min Kuo
Affiliation:
Keywords: Alzheimer’s disease, hypoglycemia, AMPK, Akt, GSK3, tau
Abstract: Cerebral hypoglycemia/hypometabolism is associated with Alzheimer’s disease (AD) and is routinely used to assist clinical diagnosis of AD by brain imaging. However, whether cerebral hypoglycemia/hypometabolism contributes to the development of AD or is a response of reduced neuronal activity remains unclear. To investigate the causal relationship, we cultured the differentiated N2a neuroblastoma cells in glucose/pyruvate-deficient media (GDM). Shortly after the N2a cells cultured in the GDM, the mitochondria membrane potential was reduced and the AMP-activated-proteinkinase (AMPK), an energy sensor, was activated. Treatment of GDM not only increased the levels of tau phosphorylation at Ser262 and Ser396, but also increased the levels of active forms of GSK3α and GSK3β, two known kinases for tau phosphorylation, of the N2a cells. The levels of activated Akt, a mediator downstream to AMPK and upstream to GSK3α/β, were reduced by the GDM treatment. The effect of hypoglycemia was further examined in vivo by intracerebroventricular (icv) injection of streptozotocin (STZ) to the Wistar rats. STZ selectively injuries glucose transporter type 2-bearing cells which are primarily astrocytes in the rat brain, hence, interrupts glucose transportation from blood vessel to neuron. STZicv injection induced energy crisis in the brain regions surrounding the ventricles, as indicated by higher pAMPK levels in the hippocampus, but not cortex far away from the ventricles. STZ-icv treatment increased the levels of phosphorylated tau and activated GSK3β, but decreased the levels of activated Akt in the hippocampus. The hippocampus-dependent spatial learning and memory was impaired by the STZ-icv treatment. In conclusion, our works suggest that hypoglycemia enhances the AMPK-Akt-GSK3 pathway and leads to tau hyperphosphorylation.
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Cite this article as:
Lee Chu-Wan, Shih Yao-Hsiang, Wu Shih-Ying, Yang Tingting, Lin Chingju and Kuo Yu-Min, Hypoglycemia Induces Tau Hyperphosphorylation, Current Alzheimer Research 2013; 10 (3) . https://dx.doi.org/10.2174/1567205011310030009
DOI https://dx.doi.org/10.2174/1567205011310030009 |
Print ISSN 1567-2050 |
Publisher Name Bentham Science Publisher |
Online ISSN 1875-5828 |
Call for Papers in Thematic Issues
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Aims and Scope: Introduction: Alzheimer's disease (AD) poses a significant global health challenge, with an increasing prevalence that demands concerted efforts to advance our understanding and strategies for prevention, diagnosis, treatment, and rehabilitation. This thematic issue aims to bring together cutting-edge research and innovative approaches from multidisciplinary perspectives to address ...read more
Current updates on the Role of Neuroinflammation in Neurodegenerative Disorders
Neuroinflammation is an invariable hallmark of chronic and acute neurodegenerative disorders and has long been considered a potential drug target for Alzheimer?s disease (AD) and dementia. Significant evidence of inflammatory processes as a feature of AD is provided by the presence of inflammatory markers in plasma, CSF and postmortem brain ...read more
Deep Learning for Advancing Alzheimer's Disease Research
Alzheimer's disease (AD) poses a significant global health challenge, with an increasing number of individuals affected yearly. Deep learning, a subfield of artificial intelligence, has shown immense potential in various domains, including healthcare. This thematic issue of Current Alzheimer Research explores the application of deep learning techniques in advancing our ...read more
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Dementia affects 18 million people worldwide. Dementia is a syndrome of symptoms caused by brain disease, usually chronic or progressive, clinically characterized by multiple impairments of higher cortical functions such as memory, thinking, orientation, and learning. In addition, in the course of dementia, cognitive deficits are observed, which often hinder ...read more
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