Fundamental Principles of Synaptic Transmission Flashcards
1
Q
how are neurotransmitters released?
A
- AP reaches the axon terminal
- voltage gated Ca2+ channels open
- influx of Ca2+ into the neurone and the Ca2+ binds to the sensor proteins in the cytoplasm
- Ca2+ protein complex stimulates the fusion of the vesicle and membrane which leads to the exocytosis of the neurotransmitter
2
Q
what are SNARES?
A
Soluble N-ethylmaleimide-sensitive factor A attachment protein Receptor
3
Q
what are the 2 types of SNARES?
A
vesicle-SNARES (v-SNARES) and target-SNARES (t-SNARES)
4
Q
what are examples of v-SNARES?
A
synaptotagmin and sunaptobrevin
5
Q
what are examples of t-SNARES?
A
syntaxin1 and SNAP25
6
Q
describe the mechanism of endocytosis
A
- Ca2+ enters the neurone and binds to synaptotagmin
- this increases the affinity to membrane phospholipids
- the vesicle binds to the membrane phospholipids which decreases the affinity to vSNARES but increases the affinity to tSNARES
- synaptobrevin binds to the tSNARES and creates a SNAREpin
- SNAREpin pulls the vesicle to the membrane which causes the vesicle to deform
- causes the neurotransmitter to be released
7
Q
why is Ach short acting?
A
they are broken down by cholinesterases
8
Q
how is Ach modulated?
A
- hemicholinium: competes w Ach for uptake
- vesamicol: prevents uptake ofAch in vesicle
- toxins: stops fusion of vesicle
- cholinesterase inhibitors: can be short acting, medium acting or long acting
9
Q
how is NA inhibited?
A
-not by an enzyme by they are taken up into extra neuronal cells
10
Q
how is NA made?
A
- tyrosine is taken into the cell and tyrosine hydroxylase converts tyrosine into DOPA
- DOPA is converted to dopamine byt DOPA carboxylase
- dopamine β hydroxylase converts dopamine into NA which can be used for metabolites or can be converted further into adrenaline
11
Q
how is NA modulated?
A
1) reserpine: stops the uptake of NA into the vesicle
2) guanethidine: displaces NA
3) drugs: inhibit uptake of NA into the neuronal transporter or compete as uptake
