Electrophysiological and Imaging Calcium Biomarkers of Aging in Male and Female 5×FAD Mice

Adam O. Ghoweri, Lara Ouillette, Hilaree N. Frazier, Katie L. Anderson, Ruei Lung Lin, John C. Gant, Rachel Parent, Shannon Moore, Geoffrey G. Murphy, Olivier Thibault, James Simpkins

Research output: Contribution to journalArticlepeer-review

Abstract

Background: In animal models and tissue preparations, calcium dyshomeostasis is a biomarker of aging and Alzheimer's disease that is associated with synaptic dysfunction, neuritic pruning, and dysregulated cellular processes. It is unclear, however, whether the onset of calcium dysregulation precedes, is concurrent with, or is the product of pathological cellular events (e.g., oxidation, amyloid-β production, and neuroinflammation). Further, neuronal calcium dysregulation is not always present in animal models of amyloidogenesis, questioning its reliability as a disease biomarker. Objective: Here, we directly tested for the presence of calcium dysregulation in dorsal hippocampal neurons in male and female 5×FAD mice on a C57BL/6 genetic background using sharp electrodes coupled with Oregon-green Bapta-1 imaging. We focused on three ages that coincide with the course of amyloid deposition: 1.5, 4, and 10 months old. Methods: Outcome variables included measures of the afterhyperpolarization, short-term synaptic plasticity, and calcium kinetics during synaptic activation. Quantitative analyses of spatial learning and memory were also conducted using the Morris water maze. Main effects of sex, age, and genotype were identified on measures of electrophysiology and calcium imaging. Results: Measures of resting Oregon-green Bapta-1 fluorescence showed significant reductions in the 5×FAD group compared to controls. Deficits in spatial memory, along with increases in Aβ load, were detectable at older ages, allowing us to test for temporal associations with the onset of calcium dysregulation. Conclusion: Our results provide evidence that reduced, rather than elevated, neuronal calcium is identified in this 5×FAD model and suggests that this surprising result may be a novel biomarker of AD.

Original languageEnglish
Pages (from-to)1419-1438
Number of pages20
JournalJournal of Alzheimer's Disease
Volume78
Issue number4
DOIs
StatePublished - 2020

Bibliographical note

Publisher Copyright:
© 2020 - IOS Press and the authors. All rights reserved.

Keywords

  • 5×FAD
  • Alzheimer's disease
  • afterhyperpolarization
  • aging
  • calcium
  • electrophysiology
  • hippocampus
  • hyperactivity
  • intracellular
  • sex

ASJC Scopus subject areas

  • Neuroscience (all)
  • Clinical Psychology
  • Geriatrics and Gerontology
  • Psychiatry and Mental health

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