L2 - Molecular determinants of the epilepsies Flashcards

1
Q

What is epilepsy?

A

Chronic neurological disorder characterised by spontaneous recurrent seizures

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2
Q

True or false

Epilepsy has no age, racial, social, gender or geographical boundaries

A

true

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3
Q

The cause of epilepsy is…

A

unknown in appox half of those suffering - genetic and acquired

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4
Q

epilepsy is thought to occur as a result of …

A

an imbalance between excitatory (glutamatergic) and inhibiry (GABA) neurotransmission - which usually work together to maintain neuronal homeostasis

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5
Q

over __% of patients don’t respond to current drug treatments

A

30%

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6
Q

Describe focal seizures:

A

Start in one region of the brain - but can then spread

usually result from an acquired brain insult

have underlying structural brain pathology

good candidates for surgery

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7
Q

Describe generalised seizures:

A

Start in both hemispheres of the brain simultaneously

Mostly genetic causes

No underlying structural brain pathology

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8
Q

Generalised non-convulsive seizures are usually ___ episodes of staring with unresponsiveness. You have have ___ per day. The have a ____ onset. Can be provolked by _______

A

Generalised non-convulsive seizures are usually brief episodes of staring with unresponsiveness. You have have hundreds per day. The have a sudden onset. Can be provolked by hyperventilation

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9
Q

True or false

Generalised non-convulsive seizures are common in childhood

A

true

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10
Q

The cause of Generalised non-convulsive seizures are unknown

A

true

but there is a strong genetic component - but more than one gene involved

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11
Q

Descibe the GAERS model

A

Genetic absense epilepsy rats from strasbourg (GAERS)

100% develop seizures by 4 months

NEC is the control strain - no seizures

polygenic: more than one gene contributing

most widely used animal model - many of the same features as human epilepsy

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12
Q

Absense seizures result from abnormal, ________ ________ activity

A

hypersynchronous thalamocortical activity

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13
Q

What makes up the thalamocortical circuit?

A

Somatosensory cortex

Ventrobasal nucleus of the thalamus

reticular nucleus of the thalamus

Two modes of firing:
awake –> tonic
sleep –> oscillatory

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14
Q

During absense seizures the brains switches to the ____ sleep moide in the thalamocortical circuit, while the person is still awake

A

Sleep –> oscillatory

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15
Q

What are the multifactorial molecular causes of genetic generalised epilepsy?

A

High/Low voltage activated Ca2+ channels

AMPA receptors

Stargazin and TARPS

GABA(a) receptors

K+ channels

voltage gated Na+ channels

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16
Q

true or false

Mutations in human Ca3.2 t-type calcium channel have been found in patients with genetic generalised epilepsy

A

true

we need to investigate how human mutations are effect calcium channel function - but study is hard in human patients

17
Q

true or false

anti-epileptic drugs work in all patients

A

false

some people they dont due to the mutations they carry

18
Q

Do GAERS have mutations n the same genes as humans with genetic generalised epilepsy (GGE)?

A

yes

Ca 3.2 mutation Ca2_ channels - changes arginine to proline

we know GAERS is polygenic tho, but it IS homozygous for this mutation

19
Q

Is the Ca 3.2 mutation highly conserved?

A

Yes - has a high homology in mammals

20
Q

The GAERS mouse has one copy of the R1584P mutation in Ca 3.2 mutation Ca2+ channels gene

A

false

two copies (PP)

exhibits spontaneous absence seizures

21
Q

By looking at heterozygous genes of the R1584P mutation we can assess…

A

the extent to which the Ca 3.2 mutation

Showed that is correlates with the epileptic phenotyle

22
Q

True or false

R1584 Ca 3.2 mutation affects seziure duration

A

false

23
Q

GGE is polygenic. How can we investigate the role of R1584 Ca 3.2 mutation in isolation?

A

Ca3.2 transgenic mouse

can be switched on/off in different cell types

24
Q

What is stargazin?

A

ubiquitously expressed in the brain

expression enriched in synaptic plasma membranes

Stabilises AMPA receptors

25
Q

Describe the features of the stargazin mouse

A

Mutation in stargazin gene

Has an epileptic, ataxic and head tossing phenotype

Has reduced stargazin mRNA and undetectable protein levels

26
Q

True or false

GAERS has a mutation in the stargazin gene

A

False

27
Q

What do AMPA receptors do?

A

mediate the actions of excitatory neurotransmitter, glutamate

28
Q

How does Stargazin modulate the AMPA receptor function?

A

AMPA receptors won’t be stable without stargazin

29
Q

Gaers have ______ stargazin mRNA expression in the ________cortex _____but not ______ the onset of seizures

A

Gaers have increased stargazin mRNA expression inthe somatosensory cortex after but not before the onset of seizures

It is a consequence of the seizures

30
Q

AMPA receptor protein is ______ specifially at the plasma membrane in gaers

A

increased

31
Q

INcreased stargazin leads to ….

A

hyperexcitability

32
Q

How can we investigate if this increase in stargazin and AMPA receptor expresion is causative of epilepsy?

A

Small interfering RNA or viral knockdown/overexpression

in an non-epileptic animal increase stargazin and/or AMPA receptor expression and see if the animal has absense seizures

33
Q

name some of the ion channels implicated in the pathophysiology of GGE

A

T-type calcium channels,
AMPA receptors
Stargazin

34
Q

True or false

mutations in humans with GGE are also present in animal models of GGE ( GAERS)

A

True