Title

Hippocampal Synaptic and Neural Network Deficits in Young Mice Carrying the Human APOE4 Gene

Department

neurology

Document Type

Article

Abstract

Introduction: Apolipoprotein E4 (APOE4)Â is a major genetic risk factor for late-onset sporadic Alzheimer disease. Emerging evidence demonstrates a hippocampus-associated learning and memory deficit in aged APOE4 human carriers and also in aged mice carrying human APOE4 gene. This suggests that either exogenous APOE4 or endogenous APOE4 alters the cognitive profile and hippocampal structure and function. However, little is known regarding how Apoe4 modulates hippocampal dendritic morphology, synaptic function, and neural network activity in young mice. Aim: In this study, we compared hippocampal dendritic and spine morphology and synaptic function of young (4Â months) mice with transgenic expression of the human APOE4 and APOE3 genes. Methods: Hippocampal dendritic and spine morphology and synaptic function were assessed by neuronal imaging and electrophysiological approaches. Results: Morphology results showed that shortened dendritic length and reduced spine density occurred at hippocampal CA1 neurons in Apoe4 mice compared to Apoe3 mice. Electrophysiological results demonstrated that in the hippocampal CA3-CA1 synapses of young Apoe4 mice, basic synaptic transmission, and paired-pulse facilitation were enhanced but long-term potentiation and carbachol-induced hippocampal theta oscillations were impaired compared to young Apoe3 mice. However, both Apoe genotypes responded similarly to persistent stimulations (4, 10, and 40Â Hz for 4Â seconds). Conclusion: Our results suggest significant alterations in hippocampal dendritic structure and synaptic function in Apoe4 mice, even at an early age.

Medical Subject Headings

neurology

Publication Date

2017

Publication Title

CNS Neuroscience and Therapeutics

ISSN

17555930

Volume

23

Issue

9

First Page

748

Last Page

758

Digital Object Identifier (DOI)

10.1111/cns.12720

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