Memory of 5xFAD APP/PS1 transgenic mice

Introduction

This page is the second part of a study of the article

Failures to reconsolidate memory in a mouse model of Alzheimer’s disease

by Masuo Ohno

Context

The model mice for this experiment were 5xFAD APP/PS1 transgenic mice.

These mice carry 5 total mutations in genes for APP production and PS production ( 3 and 2 mutations) to recreate human Alzheimers disease.

This leads to plaques that would take even 6 to 12 months to form in other transgenic mice, to develop in 2 months.

However, by 6 months, most of the hippocampus and the cortices of the transgenic mice were found to be filled with the peptide. This explains a part of the results from the experiment.

The experiment

Transgenic mice of 3 to 4 months, 6 to 7 months and 10 to 15 months were trained to associate a certain room with an electric shock.

24 hours later they were placed in that same room again. In this situation, normal mice will remember this room and show freezing behaviour.

The memory issues arising from around 6 months may be caused by Aβ filling certain brain areas, especially the hippocampus, in that time.

The youngest group of mice did too. The problem was in the older mice. Mice from 6 months of age froze less, meaning the association was no more, or at least less, in their brains.

This result however still has several possible explanations.

The decrease in freezing behaviour could be due to an issue in memory acquirement ( the perception ) or in memory consolidation ( the creation of a long term memory ).

The second experiment allows us to see which is true.

Part 1 : A fourth stage of memory consolidation & model mice

Next Part : Is memory acquisition or reconsolidation the problem in Alzheimers ?