AD: Molecular Mechanisms and Animal Models: Part II Flashcards Preview

NMH: Module 2 > AD: Molecular Mechanisms and Animal Models: Part II > Flashcards

Flashcards in AD: Molecular Mechanisms and Animal Models: Part II Deck (10)
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1

Overview of in vitro AD models?

- transfect cell lines w/ APP: neuroblastoma (as neurons don't replicate) -> measure Aβ level in medium

- AD pt specific iPSCs: same mutations]- difficult to find control as diff. ppl have differences unrelated to AD

2

Overview of in vivo AD models and advantages?

[useful for target ID & pre-clinical screening]

- rats/mice (similar brain anatomy, behav tests, NFT/plaque staging)

- fish (giant neurons-microinjections)

- worm (easy + fast breeding, cheap, ethical, powerful genetics)

- drosophilia (easy, fast breeding, cheap, ethical, powerful genetics)

3

Disadvantages of in vivo:

- rats/mice
- fish
- worm
- drosophilia

- rats/mice: time-consuming, expensive, no Aβ plaques

- fish: diff. brain anatomy, behav/staging difficult

- worm: diff. brain anatomy, behav/staging difficult

- drosophilia: diff. brain anatomy, behav/staging difficult

4

Features of rodent models that are similar to AD?

- behavioural/cognitive dysfunction

- impaired synaptic plasticity

- delta-APP processing

- amyloid plaques

5

Issues w/ rodent models of AD?

- dont develop Aβ plaques]- amino acid difference, no Aβ aggregates

- transgenetic animals express human protein (APP, presenilin, tau) e.g. APP-23 mice overexpress Swedish mutation; tau models similar to FTLD, not true AD

- double/triple trans-animals may express APP, presenilin and tau -> Aβ plaques and NFTs
BUT mice don't have large neuronal loss/atrophy (like human AD)

6

What is conditional KO?

Gene KO for certain cell type/specific brain area

(certain gene KO is embryonically lethal e.g. presenilin KO)

7

Overview of Cre-LoxP strategy for conditional gene KO?

Floxed ouse has LoxP sites around target gene (removed)

Cre mouse has Cre-Recomb enzyme inserted after specific promote

Cre recombinase only expressed in certain cell type, therefore KO (LoxP site and gene removed) only in specific cell types

8

Outcome of conditional KO of presenilin?

Decreased gamma-secretase

Mice crossed w/ APP trans-mice don't develop plaques

9

How to assess results in in vivo AD models?

- Behavioural tests (memory e.g. Morris water maze, Y maze w/ food, object recog)

- electrophysiological measures/ LTP]- assess synaptic strength

- brain imaging]- difficult to distinguish certain brain regions as mouse brains are small...rat brains are preferred for imaging

10

Outcome of intracerebral injection o AAV-vectors in WT mice? (into certain brain regions)

AAV w/ Tau -> neuronal loss in hippocampus (not seen in transgenic tau... overexpressed tau affects neuronal survival?)

AAV w/ APP -> plaques (some, not all- due to variation in experimental technique?)