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Brain alpha-amylase: a novel energy regulator important in Alzheimer disease?

Authors
  • Byman, Elin1
  • Schultz, Nina1
  • Fex, Malin2
  • Wennström, Malin1
  • 1 Clinical Memory Research Unit, Department of Clinical Sciences Malmö, Lund University, Malmö, Sweden. , (Sweden)
  • 2 Unit for Molecular Metabolism, Lund University Diabetes Centre, Department of Clinical Sciences, Lund University, Malmö, Sweden. , (Sweden)
Type
Published Article
Journal
Brain Pathology
Publisher
Wiley (Blackwell Publishing)
Publication Date
Nov 01, 2018
Volume
28
Issue
6
Pages
920–932
Identifiers
DOI: 10.1111/bpa.12597
PMID: 29485701
Source
Medline
Keywords
Language
English
License
Unknown

Abstract

Reduced glucose metabolism and formation of polyglucosan bodies (PGB) are, beside amyloid beta plaques and neurofibrillary tangles, well-known pathological findings associated with Alzheimer's disease (AD). Since both glucose availability and PGB are regulated by enzymatic degradation of glycogen, we hypothesize that dysfunctional glycogen degradation is a critical event in AD progression. We therefore investigated whether alpha (α)-amylase, an enzyme known to efficiently degrade polysaccharides in the gastrointestinal tract, is expressed in the hippocampal CA1/subiculum and if the expression is altered in AD patients. Using immunohistochemical staining techniques, we show the presence of the α-amylase isotypes AMY1A and AMY2A in neuronal dendritic spines, pericytes and astrocytes. Moreover, AD patients showed reduced gene expression of α-amylase, but conversely increased protein levels of α-amylase as well as increased activity of the enzyme compared with non-demented controls. Lastly, we observed increased, albeit not significant, load of periodic acid-Schiff positive PGB in the brain of AD patients, which correlated with increased α-amylase activity. These findings show that α-amylase is expressed and active in the human brain, and suggest the enzyme to be affected, alternatively play a role, in the neurodegenerative Alzheimer's disease pathology. © 2018 Lund University. Brain Pathology published by John Wiley & Sons Ltd on behalf of International Society of Neuropathology.

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