31 - Pharmacological overview of the PNS

Question 1

Experiment showing that neurotransmitters exist

Answer 1

Loewi’s experiment
Stimulated a perfused, beating heart with an electrically-stimulated vagus nerve (slows heart rate)
Perfusate from stimulated heart transferred to another beating heart, which also slowed.

Question 2

Major sites for pharmacological manipulation at the synapses 
1)
2)
3)
4)
5)
6)
7)
8)

Answer 2

1) Axonal transport
2) Synthesis
3) Storage
4) Metabolism
5) Release
6) Degradation
7) Uptake
8) Post-synaptic receptor

Question 3

Difference between autonomic and somatic nervous systems

Answer 3

Somatic is voluntary, directly innervates target from CNS.

Autonomic is involuntary, has pre-ganglionic and post-ganglionic neurons

Question 4

Parasympathetic innervation structure

Answer 4

Pre-ganglionic nerve reaches near, or to target organ.

Synapse between pre- and post-ganglionic nerves is around, or within target organ

Question 5

Sympathetic innervation structure

Answer 5

Pre-ganglionic nerve is short, reaches to sympathetic chain of ganglia, which lie beside spinal cord.
Post-ganglionic nerve is long, reaches to target organ

Question 6

ACh synthesis

Answer 6

Dietary choline joined to acetyl group, which comes from acetyl-CoA, from mitochondria.
Cholineacetyltransferase catalyses this reaction
ACh carrier places ACh into vesicle within neuron

Question 7

Noradrenaline synthesis
1)
2)
3)

Answer 7

1) Tyrosine converted to L-DOPA by tyrosine hydroxylase
2) L-DOPA converted to dopamine with DOPA decarboxylase
3) Dopamine converted to noradrenaline with dopamine beta-hydroxylase

Question 8

How do dopaminergic neurons prevent dopamine being converted to noradrenaline?

Answer 8

They lack dopamine beta-hydroxylase

Question 9

How is adrenaline synthesised?

Answer 9

Noradrenaline converted to adrenaline by PNMT

Question 10

How was it proven that neurons can release more than one type of neurotransmitter?

Answer 10

Guinea pig vas deferens had two-phase contraction when stimulated.
1st phase is ATP-mediated, 2nd is noradrenaline-mediated

Question 11

What does acetylcholineesterase do?

Answer 11

Converts ACh to acetate and choline

Question 12

How is ACh deactivated?

Answer 12

Degradation

Question 13

How is noradrenaline deactivated?

Answer 13

Reuptake

Question 14

How is noradrenaline reuptaken?

Answer 14

Two reuptake channels:
1) Neuronal, high-affinity uptake 1
2_ Extra-neuronal, low-affinity uptake 2

Question 15

Neurotransmitter always used for ganglionic transmission

Answer 15

ACh

Question 16

Neurotransmitter released onto target by parasympathetic neurons

Answer 16

ACh

Question 17

Neurotransmitter released onto target by sympathetic neurons

Answer 17

Noradrenaline (except for sweat glands and adrenals, where ACh is released)

Question 18

Neurotransmitter released by somatic nervous system

Answer 18

ACh

Question 19

ACh receptors

Answer 19

Nicotinic (Na+ channel)

Muscarinig (GPCR)

Question 20

Noradrenaline receptors

Answer 20

Alpha and beta adrenoceptors (GPCR)

Question 21

Examples of cholinoceptor antagonists
1)
2)

Answer 21

1) Atropine

2) d-Tubocurarine

Question 22

Alpha adrenoceptor agonist

Answer 22

Phenylephrine

Question 23

How can a receptor be unambiguously identified as being novel?

Answer 23

Cloning of receptor

Question 24

Nicotinic ACh receptor structure

Answer 24

5 protein pore.

2x alpha subunits, 1x beta subunit, 1x gamma subunit, 1x delta subunit

Question 25

Toxin that is a strong ACh receptor antagonist

Answer 25

Alpha-bungarotoxin (from a snake).

Question 26

How can Nicotinic ACh receptor be stained?

Answer 26

Conjugate a marker to alpha bungarotoxin