Stroke and excitotoxicity second half 1.0 Flashcards
What happens if the postsynaptic neuron depolarises?
Positive ions flow in
Postsynaptic receptor consequences of an excessive release of glutamate?
Activate AMPA and KAINATE receptors (both lead to Na+ going into the postsynaptic neuron (more depolarisation))
What happens to NMDA receptors at higher than -40mV?
The magnesium block is removed meaning Na+ can flow through
What does the sodium calcium exchanger do?
Protects the neurons from having too much sodium in them by swapping intracellular Na+ for extracellular Ca2+
Why does having excessive Ca2+ in a neuron cause issues?
It is a signalling molecule that can cause free radicals to form which damage the membrane and cytoskeleton
Which enzymes does Ca2+ activate?
Proteases, lipases, caspaces
What happens as a result of caspase activation?
Cell death
What happens if Ca2+ activates too much of its enzymes?
The lipid bilayer is digested (lipases), as well as anything made of proteins (proteases)
Long term effect on neurons in the core of a stroke?
They never repoalrise
What happens to the neurons in the penumbra of a stroke?
They can repolarise
What is difficult about repolarising a penumbra neuron?
The ATPase NaK pump has to work very hard to restore the concentrations of the ions to the correct level for a -70mV membrane potential, and this uses a lot of energy
Which treatment is only for thrombotic ischaemic strokes?
Tissue plasminogen activator (tPA)
What does tPA do?
Breaks down blood clots
Treatment for hemorrhagic stroke?
Surgery to fix the ruptured blood vessel
What are targets for neuroprotective agents for stroke treatment?
AMPA/NMDA receptor blockers, Na+/Ca2+ blockers, enzyme inhibitors
How could neuronal cells be recovered after a stroke?
Stem cells
What are some things that prevent people from having a stroke again?
Antihypertensives
Why are antihypertensives used to prevent stroke?
Reduce high blood pressure
What lifestyle choices can increase risk of stroke?
Obesity, lack of exercise, smoking, alcohol
For which type of stroke are blood thinners prescribed?
Ischaemic
What is a transient ischaemic attack?
Short lived neurological signs similar to those from a stroke
What do the long term stroke symptoms depend on?
The brain region affected
Symptoms if motor cortex is affected?
Skeletal muscle movement affected
Symptoms if wernicke’s area of brain is affected?
Difficulty understanding language/listening
Symptoms if Brocas area of brain is affected?
speech and writing
Symptoms if right motor cortex is comprimised?
Left half of body is affected
What random molecule can cause exitoxicity?
Domoic acid
Why can domoic acid cause excitotoxicity?
It is a glutamate receptor agonist
Where is domoic acid found?
Amnesic shellfish
What produces domoic acid?
Algae
Which glutamate agonists can cause excitotoxicity?
Domoic acid, oxalydiaminopropionic acid, beta-Methylamino-L-alanine
Which foods can cause excitotoxicity?
Shellfish, grass pea, cycad seeds
