Neurotransmitters II Flashcards
Give examples of catecholamines
Dopamine, noradrenaline, adrenaline
What is the more common name for 5-HT?
Serotonin
What is acetylcholine associated with?
- Memory
- Coordination
- Sleep cycle
- Mood
- Aggression
Reaction to form ACh
Acetyl CoA + Choline ——–> Ach
Requires choline acetyltransferase
Reaction to break down ACh
Ach ———> Choline + Acetic acid
Requires acetylcholinesterase
Which neurotransmitter is lost in Alzheimer’s?
Acetylcholine
3 ways to interfering with ACh
- Prevent release
- AChE inhibitors
- Block ACh receptors
Which organism can cause botulism and prevent the release of ACh?
Black widow spider
Example of chemical that blocks nicotinic ACh receptors
Curare
Example of chemical that blocks muscarinic ACh receptors
Atropine
Difference between muscarinic and nicotinic ACh receptors
Muscarinic receptors are G-protein couple
Nicotinic receptors are ligand-gatedd
What is the catecholamine system?
Regions of nervous system associated with movement, mood, attention, visceral function
What can tyrosine be converted to? Give example of well-known middle man
Epinephrine
Dopamine
Symptoms of Parkinson’s disease
- Temor
- Rigidity
- Monotonous slurred speech
- Akinesia
Do people suffering from Parkinson’s disease lose sensation?
No
What is the pathology of Parkinson’s disease?
Deeneration of substantial nigra
- Use dopamine for imaging in PET scan
Nigrostitial pathway
Striatum can be considered as a system that inhibits motor function
Dopamine via D2 receptors inhibits cells of striation - disinhibition
In Parkinson’s inhibition is lost therefor, increase in inhibition of motor function from striatum
What does the striatum inhibit?
Motor function
What inhibits the striatum in normal function?
Dopamine via D2 receptors
Treatment of Parkinson’s disease
- L-Dopa
- Reserpine
- Amphetamine
- Cocaine
- D2 agonists
- MAO(B) inhibitors
How can cocaine treat Parkinson’s disease?
Blocks reuptake so increases dopamine stimulation. Can also treat schizophrenia
L-Dopa treatment
Use perisperhal DDC inhibitor to stop side effects but long-term treatments will lead to problems as tolerance develops
What is chronic L-Dopa syndrome? What is it caused by?
Dopa-induced dyskinesias fluctuating with sudden and severe immobility
Caused by long-term use of L-dopa as treatment
What is dyskinesia?
Abnormality/Impairment of voluntary movement
What is the dopamine system composed of?
Dopamine and the cortical and limbic system
What do dopamine neurones inhibit the secretion of from the pituitary gland?
Prolactin
What can the overproduction of prolactin lead to?
Gynaecomastia (over-enlargement of breasts)
Galactorrhoea (spontaneous flow of milk)
What does the noradrenaline system arise from?
Locus coerulus
What metabolises catecholamines?
- Catechol-O-methyltransferase (COMT) in cytoplasm
- Monamine oxidase (MAO) on outer mitochondrial membrane
Where can you find MAO and what do they metabolise?
Outer mitochondrial membrane, liver, gut
Metabolise catecholamies
Example of transmitter that MAO-A breaks down
Noradrenealine and serotonin
Example of transmitter that MAO-B breaks down
Dopamine
What can MAO inhibitors be used to treat? How do these work
- Depression (inhibition of MAO leads to increase in NA and serotonin)
- Parkinsons (inhibition of MAO leads to increase in DA)
What is 5-HT released by?
Raphe nuclei in the brainstem
What is released by the raphe nuclei in the brainstem?
Serotonin
Treatment of depression
- Tricyclics
- Specific serotonin reuptake inhibitors i.e. fluoxetine
- MAO-A inhibitiors
Why are tricyclics used to treat depression?
Block reuptake of 5-HT and NA
MAO inhibitors and the cheese effect
MAO breaks down dietary tyramine which is sympathomimetic
MAO-I —> hypertensive crisis
How can tyramine affect blood flow?
Cannot pass blood-brain barrier
Some neurotransmitter antagonists inhibit transmitter re-uptake: true or false?
True
In the brain, a neurotransmitter can have more than one mode of action on postsynaptic cells: true or false?
True
The arrival of an action potential at a synapse causes the emptying of more than 90% of all the synaptic vesicles in the bouton: true or false?
False, the action potential a few milliseconds behind needs to release some vesicles
What is the major inhibitory neurotransmitter in the brainstem and spinal cord?
Glycine
