NT systems (Neuropharm)

Question 1

What is a NT?

Answer 1

A chemical substance whihc is released at the end of a nerve fibre by the arrival of a nerve impulse & by diffusing across the synapse or junction, effects the transfer of the impulse to another nerve fibre, a muscle fibre, or some other structure

Question 2

What are the 4 criteria for a NT?

Answer 2

1 - Substance must be synthesised in the neuron & the enzymes needed for its synthesis must be present in the neuron

2 - Must be released in sufficient quantity to elicit a response from postsynaptic neuron or cell loacted in the effector organ

3 - Mechanisms for removal or inactivation of the NT from the synaptic cleft must exist

4 - It should mimic the action of the endogenously released NT when administered exogenously at or near a synapse

Question 3

How were NTs discovered?

Answer 3

• Unclear whether communication between neurones was purely electrical or involved chemicals
• In 1921 Otto Loewi proved chemical communication
• Chemical turned out to be ACh

Question 4

What are the 3 NT classes?

Answer 4

• Small molcecule NTs
• Neuroactive peptides
• Gaseous NTs

Question 5

What are small molecule NTs?

Answer 5

• Amino acids
• Biogenic amines (monamines)
• ACh

Question 6

What are neuroactive peptides?

Answer 6

• Numerous & still being discovered
• Examples include opioids, substnace P, etc

Question 7

What are gaseous NTs?

Answer 7

Best known example is nitric oxide (NO)

Question 8

What are the stages of NT synthesis and release?

Answer 8

• Enzymes req for NT synthesis are expressed in the cell body & are transported to the nerve terminal
• NTs are synthesised from precursors taken up into the nerve terminal by transport proteins & are packaged into vesicles by other transport proteins
• Vesicles migrate to the presynaptic membrane & release their contents by exocytosis following the entry of Ca2+ into the nerve terminal
• NTs are removed by degredation or reuptake

Question 9

Watch the NT transmitter release part of the video

Answer 9

Thanks

Question 10

What are the 4 stages of synaptic vesicle recycling?

Answer 10

• Endocytosis (detached from membrane)
• Vesicle recycling and reclustering
• Dokcing and priming
• Exocytosis (attach back into membrane & release NT)

Question 11

Refer to the diagrame of the structures of small molecule NTs

Answer 11

Cool

Question 12

What are the 2 main receptor types?

Answer 12

• Ionotropic
• Metabotropic

Question 13

What are ionotropic receptors like?

Answer 13

Direct & fast response bc the receptor is also an ion channel

Also referred to as ligand-gated ion channels

Question 14

What are metabotropic receptors like?

Answer 14

Indirect & slower response bc receptor proteins are coupled to a G-protein that initiates a metabolic reaction in the cell

Also referred to as G-protein coupled receptors

Question 15

This slide contained the small molecule NT table - should be printed pls refer to this

Answer 15

:)

Question 16

What molucules are involved in glutamate synthesis?

Answer 16

• Synthesis in the neurone is from the amino acid glutamine
• Enzyme is glutaminase

Question 17

What are the 2 ways glutamate can be recycled?

Answer 17

• Direct uptake into presynaptic terminal
• OR vial glial cells

Question 18

How can glial cells take up glutamate?

Answer 18

• Glutamine is take up into glial cells and converted back into glutamine
• Enzyme is glutamine synthase
• Glutamine is transported out of the glial cell for uptake into neurones
• Uptake is complete