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Phar 505 > Cholinergic nervous system functions > Flashcards

Cholinergic nervous system functions Flashcards

1
Q

T/F: Cholinergic synapses in the parasympathetic nervous system are always preganglionic

A

False: Cholinergic synapses in the parasympathetic nervous system can be both pre- and post- ganglionic

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2
Q

What are the 3 sites that are targets of drug action involving the cholinergic synapses

A

Biosynthesis of acetylcholine, uptakes of choline and acetylcholine, release of acetylcholine

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3
Q

What is the enzyme, substrate, and coenzyme needed to create Acetylcholine

A

Choline, acetyl-CoA, choline acetyltransferase

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4
Q

What compound is a choline acetelytransferase inhibitor, how

A

NVP, imitates Acetyl-CoA and blocks binding

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5
Q

What are the major components for NVP to be an effective choline acetyltransferase inhibitor

A

napathalene ring and pyridine ring

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6
Q

What is the rate limiting step in acetylcholine production

A

uptake of choline

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7
Q

What protein is responsible for reuptaking choline into presynaptic nerve terminals

A

Carrier protein A

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8
Q

What is the competitive uptake inhibitor that reduces the amount of choline in presynaptic cells, how

A

Hemicholinium-3, it has choline like moieties that bind to the carrier protein

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9
Q

How many carrier proteins are inhibited by hemicholinium-3

A

2

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10
Q

T/F: Hemichlonium-3 is not acetlylated in presynaptic cell because it only blocks the carrier but never enters the cell

A

True

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11
Q

What is the false neurotransmitter the competes with choline for uptake by protein carrier A

A

Triethycholine (TEC)

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12
Q

T/F: Triethylcholine does not enter the cell

A

False: TEC does enter the cell and goes through the same process that choline goes through therefore competing with choline. The differece is that it is too bulky to bind to cholinergic receptors

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13
Q

What experimental drug prevents uptake of acetylcholine into vesicles

A

L-vesamicol

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14
Q

T/F: L-vesamicol does not bind competitively but instead allosterically to prevent acetylcholine binding

A

True

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15
Q

What antibiotic has a secondary effect that leads to less release of acetylcholine at a synapse, how

A

Tetracycline, complexes with calcium causing less calcium to induce release of vesicles holding acetylcholine

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16
Q

How does Botox (botulinum toxin) reduce the release of Acetylcholine

A

cleaves SNAP-25: SNAP 25 is essential for successful docking and release of acetylcholine from vesicles

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17
Q

What is the MOA of beta-Bungarotoxin

A

Causes excess release of acettylcholine that will lead to exhaustion of acetlycholine stores in the nerve terminal preventing further release of acetylcholine

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18
Q

What are the two types of receptors that bind acetylcholine

A

Muscarinic and Nicotinic

19
Q

T/F: There are muscarinic and nicotinic receptors in the CNS, Autonomic, and neuromuscular regions of the nervous system

A

False: There are only nicotinic receptors in the neuromuscular region of the nervous system. CNS and autonomic have both

20
Q

What toxin is a direct nicotinic receptor antagonist, what is the MOA

A

alpha-bungarotoxin, when replacing the calcium that keeps the sulfide bridges closed it also binds the free sulfide that would cause a conformational change that would open the channel

21
Q

Which muscarinic receptors are excitatory, what enzymes create which 2nd messengers

A

M1/M3/M5, Phospholipase C, calcium

22
Q

Which muscarinic receptors are inhibitory, what enzyme creates which 2nd messengers

A

M2/M4, Adenylate cyclase, cAMP

23
Q

T/F: Ach allows for infinite rotation around the alpha carbon but the best conformation to binding to receptors is when the quaternary amine and acetyl group are at a 90 degree angle

A

True

24
Q

What molecule could replace the nitrogen in Ach

A

Sulfur

25
Q

What are the two key needs to bind to Ach receptor

A

A positively charged group, a minimum of two methyl groups on the charged functional group

26
Q

What occurs if a methyl group is added to the alpha carbon of the ethylene bridge, what occurs when added to the beta carbon

A

selective nicotinic agonist activity, selective muscarinic agonist activity

27
Q

T/F: If a methyl group is added to the alpha and beta carbons of the ethylene bride of Ach it becomes more potent to binding to Ach receptors

A

False: There is no activity if a methyl group is added to the beta and alpha carbon of the ethylene bridge because there is to much steric hindrance that does not allow for binding

28
Q

What happens if the acetyl group is replaced by a carbamoly group in Ach, why

A

The agent then becomes orally active, carbomyls are more stable to hydrolysis

29
Q

What are anticholinergics

A

Traditionally muscarinic antagonists

30
Q

What is the most common muscarine antagonists

A

Atropine

31
Q

What are chemical features that are essential for muscarinic antagonist function

A

A quatenary or tertiary amine bonded to at least two methyl groups (quatenary would be charged and cannot enter the BBB), an aromatic ring in the opposite directions at least 5 carbons apart

32
Q

What are chemical features that are beneficial for muscarinic antagonist function

A

Hydrophobic ring, hydrogen bonding group

33
Q

Why are anticholinergics used for people with Parkinson’s disease

A

Decrease the levels of Ach to achieve a close balance with dopamine levels since Parkinson’s Disease patients have less dopamine leading to tremor and rigid muscles and the anticholinergic drugs decrease levels of Ach

34
Q

Where do nicotinic antagonists usually act

A

preganglionic synapses and neuromuscular junctions

35
Q

T/F: Nicotinic antagonists in ganglia usually act as competitive or non-competitive receptor blockers

A

True

36
Q

What is the MOA of depolorizing neuromuscular blockers type of nicotinic antagonists

A

Bind tightly to the Ach binding site of the nictonic Ach receptors and over stimulate the receptors causing more depolarizaition exhausting the receptor

37
Q

What are two common depolarizing neuromuscular blockers

A

succniylcholine and decamethonium

38
Q

What are key features of competitive neuromuscular junction blockers type of nicotinic antagonists

A

Large, charged

39
Q

What do all reversible AchE inhibitors have in common

A

All have carbamate groups attached to aromatic rings (aryl carbamates)

40
Q

What do all irreversible AchE inhibitors have in common

A

They are organophosphates

41
Q

T/F: If the irreversible AchE inhibitor is a thiophosphate it is a prodrug that is nontoxic to mammals

A

True

42
Q

T/F: Acetylcholine is converted back to choline before it is reuptook by pre-synaptic cells, then is converted to acetylcholine again

A

True

43
Q

What is the aging process with regards to irreversible organophosphate poisoning, how can this be combated

A

Water adds to the organophosphate making the bond between the organophosphate and the drug unhydrolizable, 2-PAM interacts with the drug and site to cause hydrolysis before the aging process

Phar 505 (33 decks)

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