Neurotransmission and sites of drug action

Question 1

Enzyme that is responsible for ACh synthesis

Answer 1

Choline acetyltransferase

Question 2

Enzyme responsible for ACh breakdown

Answer 2

Acetylcholinesterase

Question 3

Mechanism of ACh release

Answer 3

Stimulation of parasympathetic nerves cause calcium influx and exocytosis of ACh

Question 4

Biologic toxins that affect cholinergic neurotransmission, and their sites of action

Answer 4

Black widow spider (α-latrotoxin) - Stimulates ACh release

Botulinum toxin A - Blocks ACh exocytotic release

Question 5

Medical uses of botulinum toxin A

Answer 5

Symptomatic Parkinson treatment.
Hyperhidrosis of palms and soles
Cosmetic
Irrigation of urinary bladder in bladder spasms

Question 6

Botulinum toxin - Adverse effects

Answer 6

Dry mouth

Dysphagia

Question 7

Groups of drugs acting on cholinergic neurotransmission and MOA

Answer 7

Direct-acting ACh receptor agonists: mimic ACh effect.
Indirect acting ACh receptor agonists: cholinesterase inhibitors.
Neuromuscular blocking agents: muscarinic and nicotinic receptor antagonists.

Question 8

Enzymes responsible for norepinephrine synthesis (3 enzymes)

Answer 8

Tyrosine hydroxylase (rate-limiting).
Dopa decarboxylase
Dopamine β-hydroxylase

Question 9

MOA of norepinephrine release

Answer 9

Calcium-mediated exocytosis

Question 10

Fate of norepinephrine after postsynaptic activation

Answer 10

Reuptake to nerve by catecholamine transporter.

Inactivated in synaptic cleft by chatechol-O-methyltransferase (COMT) and monoamine oxidase (MAO)

Question 11

Groups of drugs acting on adrenergic receptors

Answer 11

Norepinephrine synthesis inhibitor (metyrosine).
Adrenoceptor antagonists (alpha-blocker, beta-blockers, both alpha and beta blockers)
Direct-acting adrenoceptor agonists
Indirect-acting adrenoceptor agonists
COMT inhibitors
MAO inhibitors