Animal Models of AD Flashcards
2 novel models in AD research
virus based models
PLB transgenic knock in mice
ideal gene delivery system
transfer genes into developing and mature animals
transduce cells with high efficiency
be cell type/tissue specific
mediate high level, long term expression
limited cytotoxicity
avoid over expression
sufficient DNA lengths
2 viral gene delivery applications
disease modelling - mutated genes, introduce genes
treatment - gene therapy, functional genes
receptors for adenovirus
coxsackie adenovirus receptor
CAR
what determines cell types virus infects and targetting capacity?
serotype
what are serotypes?
sub-groups of micro-organism which share similar antigens
viral vector systems
retrovirus
adenovirus
AAV
HSV
AD relevant AAV viruses
APP
BACe1
Tau
immunoblot
show virus expressing the gene
transgene expression
expression analyses
analysis under bright field, fluoresence and merged microscopy
vesicles taken up transgene
amyloid transfected neurons
degeneration and death
tau transfected neurons
form clusters
quantification of cell death
count % healthy neurons
defined processes, no vacuoles
what can increase % healthy neurones with tau/APP?
caffeine
problems with transgenic AD mouse models
varied promoters, no suitable controls, difficult to compare
PLB lines positives
compare triple/double/single lines
APP, tau, PS1, BACE1
instead of pronuclear injection use knock in
APP and tau - use cre/loxp to remove 1
PLB4BACE1 knock in model rational
BACE rate limiting step in production of beta amyloid
drug discovery
how to see if animal expressing hBACE1?
immunohistochemistry and western blot
increased compared to control
dentate gyrus and Ca1
APP processing in PLB4Bace1
decreased full length APP
increased cleavage products
PLB4 - brain inflammation
severe in hippocampus and cortex
GFAP astrocyte staining
PLB4BACE1 mice behaviour
decreased activity, working memory, semantic memory, anxiety, spatial memory
metabolic phenotypes of PLB4 mice
diet induced obesity and glucose intolerance
PLB4 FDD-PET imaging
less uptake of glucose in PLB4 mice in brain
increased brown adipose tissue - subtype of diabetes
type of PLB diabetes
lean type 2
AD and diabetes - what is the link?
increased risk of type 2 diabetes in AD
BACE1
CHOP
multifunctional and pro-apoptotic transcription factor
PLB - food intake and energy regulation
both increased
PTP1B
inhibitor of insulin receptor
increased in PLB4 mice
ER stress leads to what?
upregulation of CHOP
role of Ach
attention, arousal and memory
delayed matching to place
rats learn to locate platform, delay or 30s or 1 hour to trial 2
platform changed each day
what type of drug is scopolamine?
anticholinergic
acquisition of DMTP under scopolamine
learn DMTP - impair long term memory
amyloid cascade
APP, amyloid protein, amyloid deposits, neuronal toxicity
beta amyloid + scopolamine
additional effects impairs memry in water maze
where is tau found?
normally in neurons
pathologically in glia
trace amounts in heart, kidney, lung, muscle, pancreas
normal function of tau
promote tubulin assembly into MT
bundling of MT
stabilises cytoskeleton
tau in AD
Braak and Braak et al 1993
tau undergo conformational change early in AD
abnormal tau accumulate in somatodendritic compartment of neuron
3 types of tau pathology
Neurofibrillary tangles - pyramidal cells filled with paired helical and straight filaments of tau
neuritic plaques - tau around amyloid core
neuronal threads
hyperphosphorylation of tau
abnormal in AD
destabilises MT - aggregation
okadoic acid blocks phosphatases
Tau and PAPS
PAPS produces pores in cell allowing intracellular delivery of tau into hippocampal cells
then use okadaic acid - via minipump for 7 days
water maze and histology
reference memory water maze
4 days, 4 trials per day
platform same position
reversal learning - in opposite quadrant
3 types of animals in PAPS trial
only PAPS
PAPS and tau
PAPS, tau and okadaic acid
triple animals in PAPS
slow learners
reduced long term potentiation
tau in CA1 of hippocampus
phosphorylated tau in distal dendrites
