L6: Neurotransmitters & receptors

Question 1

what are the 3 types of neurotransmitter

Answer 1

• small molecule
• peptide
• gas

Question 2

types of small molecule neurotransmitters with examples

Answer 2

• ACh
• amino acids (glutamate, GABA)
• biogenic amines (adrenergics, dopamine, serotonin etc.)
• purines (ATP, adenosine)

Question 3

neurotransmission with small molecules (ACh)

Answer 3

1. Ap opens VG Ca2+ channels
2. Ca ⇒ release of vesicles from anchoring protein
3. Fuse with membrane- full or kiss and run
4. Neurotransmitter released into synnapse
5. Binds receptor temporarily-> activates receptor
6. Neurotransmitter removed by ACh-esterase which turns ACh into acetyl CoA + choline

Question 4

Ionotropic receptors

Answer 4

neurotransmitter binds → channel opens → ions flow across membrane
- when ligand not bound, channel is closed

Question 5

Metabotropic receptors

Answer 5

= GPCRs
- protein in membrane, has subunits
- Binding -> conformational change
- Causes some other effect on a different protein (effector protein) which usually goes on to activate ion channels
- For ACh, biogenic amines, neuropeptides, purines

Question 6

Glutamatergic synapse (4 steps)

Answer 6

synthesis: glutamate synthesised from glutamine
packaging: vGLUT pumpins glutamate into vesicles, uses ATP
exocytosis: into cleft where it binds to post synaptic glutamate receptors
recycling: primarily taken up by glia cell via EAAT channel which converts glutamate into glutamine so it can be transported back into presynaptic cell

Question 7

neuropeptide storage

Answer 7

large granular vesicle (LGVs) which may also contain other neurotransmitters e.g. ACh to have multiple effects

Question 8

neuropeptide action

Answer 8

• neuropeptides act on GPCRs on synaptic membrane = slow acting, long lasting
• also bind to GPCRs outside of the cleft that alters what happens in the membrane to feedback into the synapse = modulatory role

Question 9

neuropeptide example

Answer 9

hypothalamic hormones

Question 10

nitric oxide storage

Answer 10

can’t be stored because diffuses freely across membranes, so is made on demand

Question 11

NO in post-synaptic cells

Answer 11

• converts GTP to cGMP via soluble guanylyl cyclase
• cGMP is a secondary messenger- goes on and does other stuff like triggering insertion of more ion channels
  
  • so NO not directly effecting things like ion channels, but modulating