Exam 2

Question 1

Steps of drug facilitation

Answer 1

1. Drug acts as NT precursor
2. Drug stimulates NT release
3. Drug stimulates postsynaptic receptors
4. Drug blocks autoreceptors; increase release of NTs
5. Drug inhibits NT degredation
6. Drug blocks reuptake

Question 2

Steps of drug inhibition

Answer 2

1. Drug inhibits NT synthesis
2. Drug inhibits storage of NTs in vesicles
3. Drug inhibits release of NT
4. Drug blocks postsynaptic receptors
5. Drug stimulates autoreceptors; inhibits release of NTs

Question 3

how is acetylcholine made

Answer 3

in axon terminals, acetyl coenzyme A (acetyl CoA) + choline

Question 4

what is the catalyst of ACh synthesis

Answer 4

choline acetyltransferase (ChAT)

Question 5

what breaks down ACh and where

Answer 5

acetylcholinesterase (AChE) in the synapse

Question 6

ACh in PNS

Answer 6

involved in signaling in sympathetic and parasympathetic (ANS) and neuromuscular junction (SNS)

ACh is primary NT in PNS

Question 7

ACh in CNS

Answer 7

cholinergic neurons clustered in a few areas

striatum + basal forebrain cholinergic system (BFCS)

Question 8

basal forebrain cholinergic system

Answer 8

related to cognition and learning (muscarinic antagonists disrupts learning)

in nucleus basalis, substantia innominata, medial septal nucleus (projects throughout forebrain, limbic system, and hippocampus)

Question 8

striatum

Answer 8

related to Parkinson’s disease (anticholinergics decrease Parkinson’s symptoms)

stimulated by DA neurons in nigrostriatal pathway

Question 8

why are the effects of ACh on peripheral tissues important?

Answer 8

ACh is important in many tissues of the body (everywhere), so it has many side effects when used for treatment

Question 9

Black widow toxin on ACh

Answer 9

activates ACh synapses by massively increasing ACh release in PNS

Question 10

vesicular acetylcholine transporters (VAChT)

Answer 10

vesicles in axon terminal loaded with ACh by VAChT

can be blocked by vesamicol

Question 11

Botulinum toxin on ACh

Answer 11

inhibits ACh synapses by interfering with SNARE proteins at presynaptic terminal to prevent vesicular release

Question 12

what is ACh broken down into?

Answer 12

AChE breaks down ACh into choline and acetic acid

Question 13

drugs that block AChE

Answer 13

physostigmine (eserine) — pyridostigmine (mesinon) and neostigmine (prostigmin)

sarin (pyridostigmine bromide (PB - reversible AChE inhibitor; prevents nerve gas poisoning)

Question 14

criteria for identifying neurotransmitters

Answer 14

1. chemical must be synthesized or present in neuron
2. when released, chemical must produce a response in target cell
3. same receptor action must occur when chemical is experimentally or artificially placed on target
4. there must be a mechanism for removal

Question 15

Alzheimer’s Disease and ACh

Answer 15

massive neuronal loss in cortex and hippocampus (+ BFCS projecting to these parts)

AChE inhibitor drugs show little improvement to increase ACh levels

Question 16

nicotinic AChR

Answer 16

ionotropic receptor (ligand gated ion channel)

heteropentamer or homopentamer (5 subunits or alpha-7)

ligands include acetylcholine and nicotine

Question 17

what happens when a ligands binds to nicotinic AChR?

Answer 17

a channel permeable to Na+ is gated

some subtypes permeable to Ca(2+)

two molecules of ACh must bind to alpha subunits at the same time to open channel for Na+

Question 18

agonist and antagonist of nicotinic AChR

Answer 18

agonist = nicotine

antagonist = D-tubocurarine

Question 19

why are larger doses of nicotine and ACh needed to activate for muscles?

Answer 19

nicotinic receptors on muscles are less sensitive