Neurotransmitter Systems I : Glutamate Flashcards
What occurs at synapses?
β Synaptic transmission
β Electrical β chemical β electrical
What are the 3 criteria for being a neurotransmitter?
β Molecule must be synthesized and stored in the presynaptic neuron - for fast transmission
β Molecule must be released by the presynaptic axon terminal upon stimulation
β Must produce a response in the postsynaptic cells
How do vesicles fuse to the membrane?
β Change in voltage when AP occurs β Activates voltage gated Ca2+ channels β Calcium rushes into the cell β Activates the proteins on the vesicles β Signals to fuse to the synaptic membrane
Describe action potential propagation
1) At rest the voltage gated K+ and Na+ channels are closed
2) There is a depolarising stimulus
3) this activates the voltage gated Na+ channels in the membrane
4) further Na+ influx and more depolarisation
5) At the top of the peak (~ +40mv) the Na+ channels are deactivated by plugging
6) No further influx of Na+ into the cell
7) The voltage gated K+ channels are activated and opened
8) K+ flows out of the membrane down its gradient
9) Voltage decreases
10) K+ channels are open for a bit too long so it hyperpolarises
11) Na+/K+ pump restores the resting potential
Why can the action potential only travel one way?
β The sodium channels are plugged
β Na+ can only move forwards
What are the 4 main neurotransmitters?
β ACh
β Glutamate
β GABA
β Glycine
What are amino acid neurotransmitters?
β GABA
β glutamate
β glycine
Why are amino acid neurotransmitters called that?
β their precursors are amino acids
How is glutamine turned into glutamate?
β phosphate activated glutaminase
β Amine group gets substituted by an oxygen
Where is glutamate synthesized?
β In the nerve terminals
Describe how glutamate gets packaged into vesiscles
1) Glutamate is packed in the vesicles by vesicular glutamate transporter
2) It is counter transported with H+ ions
3) The intracellular environment of vesicles is very acidic so the H+ want to diffuse down their gradient
4) the transporter moves H+ out and glutamate in
Where is the AMPA receptor found?
β Post synaptically
What are the 3 ionotropic receptors for glutamate?
β AMPA
β NMDA
β Kainate
Why do the ionotropic receptors for glutamate have those names?
β They all have the endogenous agonist glutamate
β They can be activated by exogenous compounds
What are the 4 subunit types of AMPA receptors?
β GluA1
β GluA2
β GluA3
βGluA4